I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
1kv, sitting there all alone and bashfull. Not a common occurEnce.
Is this the only power source in the vicinity? Tell us more.
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>> it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
It would be cool to put two drum core inductors next to one another,
or on opposite sides of the board, to make a loosely coupled
transformer, exactly what a forward converter needs.
I've finally finished by dummy load board... Gerber day is tomorrow.
The paired Murata drum cores are spaced to tune the coupling factor to
K=0.6
https://www.dropbox.com/scl/fi/57jecrzc894uvktv72wrg/P978_A18.jpg?rlkey=4095oct5enxqp556xf44oy491&raw=1
So, how to get the low duty cycle pulsed base drive? I'm thinking
maybe an RC off the HV supply and a diac, a relaxation oscillator.
If the rig is a forward converter, we could make a non-saturating
blocking oscillator, and share the transformer secondary to drive the
base and rectify to 3.3v.
$6 or $7 might be a reasonable parts cost target in modest volume.
Needs Spicing.
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
On 19/05/2025 2:12 am, legg wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
1kv, sitting there all alone and bashfull. Not a common occurEnce.
Is this the only power source in the vicinity? Tell us more.
It's not my project. I just got asked about what a Baxandall
down-converter for a 1kV 1mA source would look like.
Because it's not my project I'm not at liberty to talk about the power >source. My first thought was an intensely radio-active source pushing
out a lot of high energy beta rays (electrons) or alpha rays (helium
nuclei), but it isn't.
On Mon, 19 May 2025 18:27:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 2:12 am, legg wrote:It sort of limits your ability to help.
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>> it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>> which there is an LTSpice model?
1kv, sitting there all alone and bashfull. Not a common occurEnce.
Is this the only power source in the vicinity? Tell us more.
It's not my project. I just got asked about what a Baxandall
down-converter for a 1kV 10uA source would look like.
Because it's not my project I'm not at liberty to talk about the power
source. My first thought was an intensely radio-active source pushing
out a lot of high energy beta rays (electrons) or alpha rays (helium
nuclei), but it isn't.
At 1W, you should be able to get away with murder, if efficiency
isn't really an issue.
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
It would be cool to put two drum core inductors next to one another,
or on opposite sides of the board, to make a loosely coupled
transformer, exactly what a forward converter needs.
You end up needing a lot more core material than the Baxandall
configuration does. Been there, been pissed off by that.
I've finally finished by dummy load board... Gerber day is tomorrow.
The paired Murata drum cores are spaced to tune the coupling factor to
K=0.6
https://www.dropbox.com/scl/fi/57jecrzc894uvktv72wrg/P978_A18.jpg?rlkey=4095oct5enxqp556xf44oy491&raw=1
So, how to get the low duty cycle pulsed base drive? I'm thinking
maybe an RC off the HV supply and a diac, a relaxation oscillator.
The Baxandall configuration lends itself to simple drive circuits.
If the rig is a forward converter, we could make a non-saturating
blocking oscillator, and share the transformer secondary to drive the
base and rectify to 3.3v.
Of course you could, but you'd need to be mad to try.
$6 or $7 might be a reasonable parts cost target in modest volume.
Needs Spicing.
Which is why I am looking for a Spice model of the 1.7kV transistor I
know I can buy.
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse? Neon tubes >illuminating a solar cell? Capacitive divider using a spare core in the >mains supply lead as one plate of the capacitor? (Depending on supply >frequency and required output current.)
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>> need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>> be grateful for your insights into a cheaper alternative. I can't think >>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
It would be cool to put two drum core inductors next to one another,
or on opposite sides of the board, to make a loosely coupled
transformer, exactly what a forward converter needs.
You end up needing a lot more core material than the Baxandall
configuration does. Been there, been pissed off by that.
I've finally finished by dummy load board... Gerber day is tomorrow.
The paired Murata drum cores are spaced to tune the coupling factor to
K=0.6
https://www.dropbox.com/scl/fi/57jecrzc894uvktv72wrg/P978_A18.jpg?rlkey=4095oct5enxqp556xf44oy491&raw=1
So, how to get the low duty cycle pulsed base drive? I'm thinking
maybe an RC off the HV supply and a diac, a relaxation oscillator.
The Baxandall configuration lends itself to simple drive circuits.
If the rig is a forward converter, we could make a non-saturating
blocking oscillator, and share the transformer secondary to drive the
base and rectify to 3.3v.
Of course you could, but you'd need to be mad to try.
$6 or $7 might be a reasonable parts cost target in modest volume.
Needs Spicing.
Which is why I am looking for a Spice model of the 1.7kV transistor I
know I can buy.
You are so smart that you obviously don't need my help.
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>> it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
Trickle charge for start-up, with all control power on the LV side;
an intermediate 8-20V rail.
From there it's a matter of your tech arranging 'who's on first'
in a sensible manner.
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
It would be cool to put two drum core inductors next to one another,
or on opposite sides of the board, to make a loosely coupled
transformer, exactly what a forward converter needs.
You end up needing a lot more core material than the Baxandall configuration does. Been there, been pissed off by that.
I've finally finished by dummy load board... Gerber day is tomorrow.
The paired Murata drum cores are spaced to tune the coupling factor to
K=0.6
https://www.dropbox.com/scl/fi/57jecrzc894uvktv72wrg/P978_A18.jpg?rlkey=4095oct5enxqp556xf44oy491&raw=1
So, how to get the low duty cycle pulsed base drive? I'm thinking
maybe an RC off the HV supply and a diac, a relaxation oscillator.
The Baxandall configuration lends itself to simple drive circuits.
If the rig is a forward converter, we could make a non-saturating
blocking oscillator, and share the transformer secondary to drive the
base and rectify to 3.3v.
Of course you could, but you'd need to be mad to try.
$6 or $7 might be a reasonable parts cost target in modest volume.
Needs Spicing.
Which is why I am looking for a Spice model of the 1.7kV transistor I know I can buy.
--
Bill Sloman, Sydney
I'm looking at a problem where somebody wants to step down a 1kV low current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would
do it - though it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for which there is an LTSpice model?
--
Bill Sloman, Sydney
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being helpful.
--
Bill Sloman, Sydney
On 19/05/2025 10:48 pm, legg wrote:
On Mon, 19 May 2025 18:27:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 2:12 am, legg wrote:It sort of limits your ability to help.
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>> which there is an LTSpice model?
1kv, sitting there all alone and bashfull. Not a common occurEnce.
Is this the only power source in the vicinity? Tell us more.
It's not my project. I just got asked about what a Baxandall
down-converter for a 1kV 10uA source would look like.
Because it's not my project I'm not at liberty to talk about the power
source. My first thought was an intensely radio-active source pushing
out a lot of high energy beta rays (electrons) or alpha rays (helium
nuclei), but it isn't.
I know what the power source is - in general terms. I haven't got any
kind of okay to talk about it
At 1W, you should be able to get away with murder, if efficiency
isn't really an issue.
Efficiency is an issue, if only on the sense that a 0.1W power source
isn't up to much, so even 50% efficiency would be nice. Jim Williams got >about 93% out of the Baxandall configuration, but 50% might be good enough.
Bill Sloman, Sydney
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
exploited the Baxandal configuration to get the voltages they need out
of low voltage supplies, using bipolar transistor switches. I would not
be all that optimistic about finding a CCFL transformer that I could >repurpose.
Designing a transformer for the job isn't all that difficult and finding
a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >regular silicon part with a higher on resistance and about ten times the >internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might
work, even if still too expensive to be attractive.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100fo6f$1nipq$1@dont-email.me...
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being helpful.
Why shoud he Bill? When all he gets from you is "you'd need to be mad to try".
--
Bill Sloman, Sydney
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>> need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>> be grateful for your insights into a cheaper alternative. I can't think >>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
https://www.google.com/search?q=1400v+npn+st
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100fo6f$1nipq$1@dont-email.me...
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being helpful.
Why shoud he Bill? When all he gets from you is "you'd need to be mad to try".
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>> need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>> be grateful for your insights into a cheaper alternative. I can't think >>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
On Mon, 19 May 2025 14:28:39 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100fo6f$1nipq$1@dont-email.me...
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being helpful.
Why shoud he Bill? When all he gets from you is "you'd need to be mad to try".
Some people have ideas, and like to play with them as a kind of team
sport.
Some people don't have ideas and want to club them to death at birth.
On Mon, 19 May 2025 14:26:55 -0400, "Edward Rawde"They do have an LT Spice model library that works.
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman
<bill.sloman@ieee.org> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman
<bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step
down a 1kV low current source to 3.3V.
The Baxandall class-D oscillator could do it, but it
needs a pair 1.7kV MOSFETs for the job. The Infineon SiC
IMH170R450M1 would do it - though it's a much higher
current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises
LTSpice models, but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and
smaller - part for which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my
Pockels Cell driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
Gate drive for SiC parts is a bear. I did it myself, but I
think there are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low
power converter. The drain swing is 2x the supply voltage,
and it needs two fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is
famous efficient.
The drain swing is actually 1.67 times the supply voltage,
but it does need two switching devices and a specially wound
transformer (and we know how reluctant you are to design them
or get them made).
It is probably going to be too expensive for the application,
and we'd be grateful for your insights into a cheaper
alternative. I can't think of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio
transformer. Coilcraft makes some, capacitor charging
transformers and CCFLs. There must be crazy cheap Indian or
Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a
search engine.
https://www.google.com/search?q=1400v+npn+st
The STN0214 is a cute little 1200 volt SOT-223 for 70 cents at 100.
1400 volts in real life.
Roger about using search engines to, well, search for things.
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>> need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>> be grateful for your insights into a cheaper alternative. I can't think >>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
exploited the Baxandal configuration to get the voltages they need out
of low voltage supplies, using bipolar transistor switches. I would not
be all that optimistic about finding a CCFL transformer that I could
repurpose.
Designing a transformer for the job isn't all that difficult and finding
a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200
regular silicon part with a higher on resistance and about ten times the
internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might
work, even if still too expensive to be attractive.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100c4og$t4lo$1@dont-email.me...
I'm looking at a problem where somebody wants to step down a 1kV low current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would
do it - though it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for which there is an LTSpice model?
I don't know of a specific part but a few seconds with a search engine found this:
https://www.allaboutcircuits.com/technical-articles/how-to-simulate-silicon-carbide-transistors-with-ltspice/
On Mon, 19 May 2025 23:12:50 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 10:48 pm, legg wrote:
On Mon, 19 May 2025 18:27:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 2:12 am, legg wrote:It sort of limits your ability to help.
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
1kv, sitting there all alone and bashfull. Not a common occurEnce.
Is this the only power source in the vicinity? Tell us more.
It's not my project. I just got asked about what a Baxandall
down-converter for a 1kV 10uA source would look like.
Because it's not my project I'm not at liberty to talk about the power >>>> source. My first thought was an intensely radio-active source pushing
out a lot of high energy beta rays (electrons) or alpha rays (helium
nuclei), but it isn't.
I know what the power source is - in general terms. I haven't got any
kind of okay to talk about it
At 1W, you should be able to get away with murder, if efficiency
isn't really an issue.
Efficiency is an issue, if only on the sense that a 0.1W power source
isn't up to much, so even 50% efficiency would be nice. Jim Williams got
about 93% out of the Baxandall configuration, but 50% might be good enough.
1KV 1ma 1W. Anything low powered will have efficiency issues
At 100mW it's a different animal.
I was suggesting a repurposed CCFL transformer for use as an
inductor in a buck reg configuration, because they're cheap,
available and wound for high voltage with low distributed
capacitance. The normal drive winding addresses 8-20V bulh
control. Backwards, like I suggested.
Lowest frequency to deal with other caps in the viscinity, as
the original CCFL will have sensibly done.
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
Neon tubes illuminating a solar cell?
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply frequency and required output current.)
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply frequency and required output current.)
I can't see how that could work.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
And a drive transformer with two secondary windings for the base current in each.
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>>> need two switching devices and a specially wound transformer (and we >>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
I found the Infineon INWH170R450M1 part for which I'm now looking for a Spice model with exactly that kind of search string.
I've been jumping through Infineon's support hoops for a couple of days now, and they haven't yet even admitted that they have a
Spice model
--
Bill Sloman, Sydney
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
Trickle charge for start-up, with all control power on the LV side;
an intermediate 8-20V rail.
From there it's a matter of your techy arranging 'who's on first'
in a sensible manner.
RL
On 20/05/2025 4:35 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100c4og$t4lo$1@dont-email.me...
I'm looking at a problem where somebody wants to step down a 1kV low current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would
do it - though it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for which there is an LTSpice model?
I don't know of a specific part but a few seconds with a search engine found this:
https://www.allaboutcircuits.com/technical-articles/how-to-simulate-silicon-carbide-transistors-with-ltspice/
Teaching grandmothers to suck eggs.
The latest version of LTSpice seems to want you to use Notepad on the .asc file to modify the transistor symbol. I didn't used to
have to do that.
--
Bill Sloman, Sydney
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>>> which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient. >>>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>>> need two switching devices and a specially wound transformer (and we >>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>
exploited the Baxandal configuration to get the voltages they need out
of low voltage supplies, using bipolar transistor switches. I would not
be all that optimistic about finding a CCFL transformer that I could
repurpose.
Designing a transformer for the job isn't all that difficult and finding >>> a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >>> regular silicon part with a higher on resistance and about ten times the >>> internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might
work, even if still too expensive to be attractive.
<snipped badly formatted list>
The highest voltage part in there was good for 1.5kV, so not good enough.
On 20/05/2025 4:28 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:100fo6f$1nipq$1@dont-email.me...
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman
<bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman
<bill.sloman@ieee.org>
wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being
helpful.
Why shoud he Bill? When all he gets from you is "you'd need to be mad
to try".
If I had thought that he might be helpful, I'd have been more diplomatic.
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>>
exploited the Baxandal configuration to get the voltages they need out >>>> of low voltage supplies, using bipolar transistor switches. I would not >>>> be all that optimistic about finding a CCFL transformer that I could
repurpose.
Designing a transformer for the job isn't all that difficult and finding >>>> a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >>>> regular silicon part with a higher on resistance and about ten times the >>>> internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might
work, even if still too expensive to be attractive.
<snipped badly formatted list>
The highest voltage part in there was good for 1.5kV, so not good enough.
Bill, the Baxandal cct is great in lower voltage input applications,
but the one thing you don't want to do with HV sources is ADD voltage
stress.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
And a drive transformer with two secondary windings for the base current in each.
On 20/05/2025 08:26, Bill Sloman wrote:
On 20/05/2025 4:28 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message
news:100fo6f$1nipq$1@dont-email.me...
On 19/05/2025 11:29 pm, john larkin wrote:...much snippage
On Mon, 19 May 2025 18:19:36 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman
<bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman
<bill.sloman@ieee.org>
wrote:
You are so smart that you obviously don't need my help.
I clearly need help here, but you don't seem to interested in being
helpful.
Why shoud he Bill? When all he gets from you is "you'd need to be mad
to try".
If I had thought that he might be helpful, I'd have been more diplomatic.
Others may be refrain from running to your assistance in anticipation of
your gracious response.
I've been posting here for more than twenty years.
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>>
exploited the Baxandal configuration to get the voltages they need out >>>> of low voltage supplies, using bipolar transistor switches. I would not >>>> be all that optimistic about finding a CCFL transformer that I could
repurpose.
Designing a transformer for the job isn't all that difficult and finding >>>> a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was
really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >>>> regular silicon part with a higher on resistance and about ten times the >>>> internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might
work, even if still too expensive to be attractive.
<snipped badly formatted list>
The highest voltage part in there was good for 1.5kV, so not good enough.
Bill, the Baxandal cct is great in lower voltage input applications,
but the one thing you don't want to do with HV sources is ADD voltage
stress.
Hence recommendation for buck-type topologies.
If the Baxandal could be reconfigured as a half-bridge, it might fly
here.
Still don't know what the actual 3V3 power demand is, but if the
source is not limited, as you suggest somewhere else, then safe
limiting will be an issue.
On Tue, 20 May 2025 10:53:58 -0400, legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
Bill, the Baxandal cct is great in lower voltage input applications,
but the one thing you don't want to do with HV sources is ADD voltage
stress.
Bax is, as the saying goes, "component rich."
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply
frequency and required output current.)
I can't see how that could work.
If you used a three-core mains lead with one of the cores connected to Neutral at the plug, one to Live at the plug and one floating, the
floating lead would take up a potential somewhere between the other two,
the stray capacitances between the leads acting as a capacitive divider.
The Live and Neutral leads are left unconnected at the equipment end and
the floating lead is connected to a rectifier system which takes it's
earth reference from the equipment being supplied. It would be
approximately a constant-current supply, so a capacitor and zener diode
would be sufficient to stabilise it at the required low voltage.
The mains lead is acting as a high voltage capacitor but is a lot
cheaper and more reliable.
If you need a solid earth on the output, use a four-core cable.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hcgk$24itl$6@dont-email.me...
On 20/05/2025 4:35 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100c4og$t4lo$1@dont-email.me...
I'm looking at a problem where somebody wants to step down a 1kV low current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would
do it - though it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for which there is an LTSpice model?
I don't know of a specific part but a few seconds with a search engine found this:
https://www.allaboutcircuits.com/technical-articles/how-to-simulate-silicon-carbide-transistors-with-ltspice/
Teaching grandmothers to suck eggs.
The latest version of LTSpice seems to want you to use Notepad on the .asc file to modify the transistor symbol. I didn't used to
have to do that.
I can right click any file and edit it with anything I like here. Ususally Notepad++
If search engines are a challenge then I can understand that "open with" might also be.
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote:
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A ccfl transformer is ideal for the HV step-down application, and dirt
cheap is a side benefit.
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
I'd expect that the transformer and one transistor and a few passives would make a basic step-down converter without low-side logic to power up.
Parts cost could get below $3 for a regulated 1K to 3.3 supply, $2 in quantity.
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>>> need two switching devices and a specially wound transformer (and we >>>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>>> of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer.
Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
And if I can buy a 1.7kV SiC MOSFET, why would I bother to stack two transistors?
And a drive transformer with two secondary windings for the base current in each.
Sure. John Larkin can't be bothered to design special purpose transformers, or get then made, but you want to remind us that that
it is still an option.
The classic Baxandall transformer usually has two base drive windings. You tend to need a coil former with lots of pins for its
transformer.
--
Bill Sloman, Sydney
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply
frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current multiplication, but about the only kind of switch that would work would
be a reed relay, and they are slow and don't last long when cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for
about 100 million, and neither is all that cheap or compact.
On 21/05/2025 1:44 am, john larkin wrote:
On Tue, 20 May 2025 10:53:58 -0400, legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
<snip>
Bill, the Baxandal cct is great in lower voltage input applications,
but the one thing you don't want to do with HV sources is ADD voltage
stress.
Bax is, as the saying goes, "component rich."
It's a more complicated circuit than John Larkin likes to play with.
It's got a special purpose transformer, the feed inductor and two
switching transistors. In theory you have to add a capacitor across the >transformer to create the resonant tank, but for the application I'm
talking about it may be difficult to wind the transformer with a low
enough parallel capacitance to get the sort of resonant frequency I'd
like to see.
That's not a lot of components.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>>>> need two switching devices and a specially wound transformer (and we >>>>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>>>> be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer. >>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>>>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
In any case there was no transistor capable of doing horizontal deflection and EHT for a 20 or more inch CRT before the late 60s.
My father was never without a spare PL36.
On Wed, 21 May 2025 03:15:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 1:44 am, john larkin wrote:
On Tue, 20 May 2025 10:53:58 -0400, legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 20/05/2025 5:48 am, legg wrote:
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
<snip>
Bill, the Baxandal cct is great in lower voltage input applications,
but the one thing you don't want to do with HV sources is ADD voltage
stress.
Bax is, as the saying goes, "component rich."
It's a more complicated circuit than John Larkin likes to play with.
It's got a special purpose transformer, the feed inductor and two
switching transistors. In theory you have to add a capacitor across the
transformer to create the resonant tank, but for the application I'm
talking about it may be difficult to wind the transformer with a low
enough parallel capacitance to get the sort of resonant frequency I'd
like to see.
That's not a lot of components.
It doesn't matter how complex your circuits are, since they will never
be built.
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>> it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>> which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply
frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for
about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>> frequency and required output current.)
I can't see how that could work.
If you used a three-core mains lead with one of the cores connected to Neutral at the plug, one to Live at the plug and one floating, the
floating lead would take up a potential somewhere between the other two, the stray capacitances between the leads acting as a capacitive divider.
The Live and Neutral leads are left unconnected at the equipment end and the floating lead is connected to a rectifier system which takes it's
earth reference from the equipment being supplied. It would be approximately a constant-current supply, so a capacitor and zener diode would be sufficient to stabilise it at the required low voltage.
The mains lead is acting as a high voltage capacitor but is a lot
cheaper and more reliable.
If you need a solid earth on the output, use a four-core cable.
That's a lot of words but doesn't describe anything that takes a small
direct current at high voltage and turns it into larger current at a low voltage.
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked
back and my first <sci.electronic.design> post was 20 years and 4 months
ago.
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked >back and my first <sci.electronic.design> post was 20 years and 4 months >ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
On 21/05/2025 12:53 am, legg wrote:
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:Bill, the Baxandal cct is great in lower voltage input applications,
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there >>>>>>>> are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power
converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>>> need two switching devices and a specially wound transformer (and we >>>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50) >>>>>> transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
Cold cathode fluorescent lamps are cranky beasts, and Jim Williams
exploited the Baxandal configuration to get the voltages they need out >>>>> of low voltage supplies, using bipolar transistor switches. I would not >>>>> be all that optimistic about finding a CCFL transformer that I could >>>>> repurpose.
Designing a transformer for the job isn't all that difficult and finding >>>>> a local transformer shop to wind it wasn't all that hard when I did
something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was >>>>>> really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >>>>> regular silicon part with a higher on resistance and about ten times the >>>>> internal capacitances. I'm not recommending SiC on principle - the
limited search I did came up with a SiC part which looked as if might >>>>> work, even if still too expensive to be attractive.
<snipped badly formatted list>
The highest voltage part in there was good for 1.5kV, so not good enough. >>
but the one thing you don't want to do with HV sources is ADD voltage
stress.
The usual Baxandall circuit does generate a peak voltage that's 1.67
times the supply voltage. Non-resonant switchers tend to generate
switching spikes that go even higher.
Hence recommendation for buck-type topologies.
I've played with them at the design stage from time to time. I've never
been all that happy with what they've offered.
If the Baxandal could be reconfigured as a half-bridge, it might fly
here.
Here is Baxandall's original paper - I put a copy on my website more
than ten years ago.
http://www.sophia-electronica.com/Baxandall1959JM.pdf
It includes a number of possible configurations.
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked
back and my first <sci.electronic.design> post was 20 years and 4 months
ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
Bill Sloman <bill.sloman@ieee.org> wrote:
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
That's a lot of words but doesn't describe anything that takes a small
direct current at high voltage and turns it into larger current at a low
voltage.
The original post didn't say that it was a direct current source.
My comment "Depending on supply frequency and required output current."
would have given you a clue that I was assuming an A.C. source.
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we >>>>>>>>> know how reluctant you are to design them or get them made). >>>>>>>>>
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer. >>>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There >>>>>>>> must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
In any case there was no transistor capable of doing horizontal deflection and EHT for a 20 or more inch CRT before the late
60s.
My father was never without a spare PL36.
So what.
<snip>
--
Bill Sloman, Sydney
On 21/05/2025 9:05 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
<snip>
That's a lot of words but doesn't describe anything that takes a small
direct current at high voltage and turns it into larger current at a low >> voltage.
The original post didn't say that it was a direct current source.
The fact that it doesn't mention a frequency might have given you a
clue, as should the comment that "The Baxandall class-D oscillator could
do it". A transformer would have been enough for an AC source.
My comment "Depending on supply frequency and required output current." would have given you a clue that I was assuming an A.C. source.
It had to be that or something equally daft.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >> >>> frequency and required output current.)
I can't see how that could work.
If you used a three-core mains lead with one of the cores connected to
Neutral at the plug, one to Live at the plug and one floating, the
floating lead would take up a potential somewhere between the other two, >> > the stray capacitances between the leads acting as a capacitive divider. >> >
The Live and Neutral leads are left unconnected at the equipment end and >> > the floating lead is connected to a rectifier system which takes it's
earth reference from the equipment being supplied. It would be
approximately a constant-current supply, so a capacitor and zener diode
would be sufficient to stabilise it at the required low voltage.
The mains lead is acting as a high voltage capacitor but is a lot
cheaper and more reliable.
If you need a solid earth on the output, use a four-core cable.
That's a lot of words but doesn't describe anything that takes a small
direct current at high voltage and turns it into larger current at a low
voltage.
The original post didn't say that it was a direct current source. My
comment "Depending on supply frequency and required output current."
would have given you a clue that I was assuming an A.C. source.
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100jsf2$2n1hq$2@dont-email.me...
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we >>>>>>>>>> know how reluctant you are to design them or get them made). >>>>>>>>>>
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer. >>>>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
Does the word "hyperbole" mean anything to you Bill?
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100jsf2$2n1hq$2@dont-email.me...
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we >>>>>>>>>> know how reluctant you are to design them or get them made). >>>>>>>>>>
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer. >>>>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
Does the word "hyperbole" mean anything to you Bill?
A search engine should help.
I don't mean (x^2)/(a^2)-(y^2)/(b^2)=1
On Wed, 21 May 2025 09:42:11 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100jsf2$2n1hq$2@dont-email.me...
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made). >>>>>>>>>>>
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas.
One could make a flyback converter with a high-ratio transformer. >>>>>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers.
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't
have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
Does the word "hyperbole" mean anything to you Bill?
He's obviously unwell.
On Wed, 21 May 2025 03:05:26 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:53 am, legg wrote:Ran across similar circuits, used to power CCFL lamps on canal boats
On Tue, 20 May 2025 17:49:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 20/05/2025 5:48 am, legg wrote:Bill, the Baxandal cct is great in lower voltage input applications,
On Tue, 20 May 2025 03:21:37 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 11:33 pm, legg wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell >>>>>>>>> driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two >>>>>>>>> fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does >>>>>>>> need two switching devices and a specially wound transformer (and we >>>>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>>>> be grateful for your insights into a cheaper alternative. I can't think
of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50) >>>>>>> transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
Cold cathode fluorescent lamps are cranky beasts, and Jim Williams >>>>>> exploited the Baxandal configuration to get the voltages they need out >>>>>> of low voltage supplies, using bipolar transistor switches. I would not >>>>>> be all that optimistic about finding a CCFL transformer that I could >>>>>> repurpose.
Designing a transformer for the job isn't all that difficult and finding >>>>>> a local transformer shop to wind it wasn't all that hard when I did >>>>>> something similar in the Netherlands some twenty years ago.
A 1KV mosfet (why SIC?) would act as it's own TVS if the source was >>>>>>> really self-limited. 2$
The SIC part costs about $5.00. The guy I'm talking to came up with $200 >>>>>> regular silicon part with a higher on resistance and about ten times the >>>>>> internal capacitances. I'm not recommending SiC on principle - the >>>>>> limited search I did came up with a SiC part which looked as if might >>>>>> work, even if still too expensive to be attractive.
<snipped badly formatted list>
The highest voltage part in there was good for 1.5kV, so not good enough. >>>
but the one thing you don't want to do with HV sources is ADD voltage
stress.
The usual Baxandall circuit does generate a peak voltage that's 1.67
times the supply voltage. Non-resonant switchers tend to generate
switching spikes that go even higher.
Hence recommendation for buck-type topologies.
I've played with them at the design stage from time to time. I've never
been all that happy with what they've offered.
If the Baxandal could be reconfigured as a half-bridge, it might fly
here.
Here is Baxandall's original paper - I put a copy on my website more
than ten years ago.
http://www.sophia-electronica.com/Baxandall1959JM.pdf
It includes a number of possible configurations.
and caravans in the UK, off 6V and 12V accumulators.
In NA, they tended to go straight for a 120VAC inverter buss and COTS hardware.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 21/05/2025 9:05 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
<snip>
That's a lot of words but doesn't describe anything that takes a small >>>> direct current at high voltage and turns it into larger current at a low >>>> voltage.
The original post didn't say that it was a direct current source.
The fact that it doesn't mention a frequency might have given you a
clue, as should the comment that "The Baxandall class-D oscillator could
do it". A transformer would have been enough for an AC source.
My comment "Depending on supply frequency and required output current."
would have given you a clue that I was assuming an A.C. source.
It had to be that or something equally daft.
Ask a daft (or incompletely-specified) question and you must expect an
answer that seems daft to you.
legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked
back and my first <sci.electronic.design> post was 20 years and 4 months
ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
I have an archive on my machine going back to about 2000, when I first >started using Usenet. Google was just a useful new search engine at
that time, not the ubiquitous, intrusive, data-devouring monster it has
since grown into.
On Wed, 21 May 2025 09:42:11 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100jsf2$2n1hq$2@dont-email.me...
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
Does the word "hyperbole" mean anything to you Bill?
He's obviously unwell.
On Wed, 21 May 2025 13:03:33 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked >>>> back and my first <sci.electronic.design> post was 20 years and 4 months >>>> ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
I have an archive on my machine going back to about 2000, when I first
started using Usenet. Google was just a useful new search engine at
that time, not the ubiquitous, intrusive, data-devouring monster it has
since grown into.
Their charter used to include "Don't be evil" but that was deleted.
Evil turned out to be more profitable.
"john larkin" <jl@glen--canyon.com> wrote in message news:8osr2klq9oepgqsva13nljp4aikmh75rkv@4ax.com...
On Wed, 21 May 2025 09:42:11 -0400, "Edward Rawde"
<invalid@invalid.invalid> wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100jsf2$2n1hq$2@dont-email.me...
On 21/05/2025 3:44 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100ibpi$2at8a$2@dont-email.me...
On 20/05/2025 11:38 pm, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100hb9s$24itl$3@dont-email.me...
On 20/05/2025 4:26 am, Edward Rawde wrote:
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:100epio$1h4ca$1@dont-email.me...
On 19/05/2025 1:38 pm, john larkin wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
I use a Cree/Wolfspeed 1200v part, C2M0280120D, in my Pockels Cell
driver.
https://www.dropbox.com/scl/fi/5arhyamrp0bl3tgb2fasn/DSC02771.JPG?rlkey=3ttcc2yt6s9nrtdouuv3aneol&raw=1
They do have an LT Spice model library that works.
Gate drive for SiC parts is a bear. I did it myself, but I think there
are chips for that now.
There are multi-kilovolt silicon mosfets too.
Baxandal looks to be inefficient and expensive as a low power >>>>>>>>>>>>> converter. The drain swing is 2x the supply voltage, and it needs two
fets and a difficult custom transformer.
It isn't going to be inefficient. That configuration is famous efficient.
The drain swing is actually 1.67 times the supply voltage, but it does
need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made). >>>>>>>>>>>>
It is probably going to be too expensive for the application, and we'd
be grateful for your insights into a cheaper alternative. I can't think
of one.
I'm not sure what the specs are, but I have a few ideas. >>>>>>>>>>>
One could make a flyback converter with a high-ratio transformer. >>>>>>>>>>> Coilcraft makes some, capacitor charging transformers and CCFLs. There
must be crazy cheap Indian or Chinese CCFL transformers. >>>>>>>>>>>
ST makes a 1400v NPN transistor for under a dollar.
But you can't be bothered to post the part number.
What you should have said is that you couldn't be bothered to use a search engine.
I need at least 1.7kV. A 1400V part isn't interesting.
Centuries ago they'd put two transistors in series in the TV horizontal deflection department because a single one didn't
have
enough Vce max.
The transistor was invented in the 1950's. Decades ago is closer to the mark.
LOL sane people would have known what I meant without needing to point that out Bill.
Sane people don't say "centuries" when they mean "decades".
Does the word "hyperbole" mean anything to you Bill?
He's obviously unwell.
Yes I think you're right so I'm going to leave it there.
On Wed, 21 May 2025 12:05:28 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 20/05/2025 7:58 pm, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
[...]
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>> frequency and required output current.)
I can't see how that could work.
If you used a three-core mains lead with one of the cores connected to >>>> Neutral at the plug, one to Live at the plug and one floating, the
floating lead would take up a potential somewhere between the other two, >>>> the stray capacitances between the leads acting as a capacitive divider. >>>>
The Live and Neutral leads are left unconnected at the equipment end and >>>> the floating lead is connected to a rectifier system which takes it's
earth reference from the equipment being supplied. It would be
approximately a constant-current supply, so a capacitor and zener diode >>>> would be sufficient to stabilise it at the required low voltage.
The mains lead is acting as a high voltage capacitor but is a lot
cheaper and more reliable.
If you need a solid earth on the output, use a four-core cable.
That's a lot of words but doesn't describe anything that takes a small
direct current at high voltage and turns it into larger current at a low >>> voltage.
The original post didn't say that it was a direct current source. My
comment "Depending on supply frequency and required output current."
would have given you a clue that I was assuming an A.C. source.
Bill has informed you that you are stupid. Apologize and be more
respectful in the future.
john larkin <jl@glen--canyon.com> wrote:
On Wed, 21 May 2025 13:03:33 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked >>>>> back and my first <sci.electronic.design> post was 20 years and 4 months >>>>> ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
I have an archive on my machine going back to about 2000, when I first
started using Usenet. Google was just a useful new search engine at
that time, not the ubiquitous, intrusive, data-devouring monster it has
since grown into.
Their charter used to include "Don't be evil" but that was deleted.
Evil turned out to be more profitable.
In the short run, which is all they know about.
On Wed, 21 May 2025 13:03:33 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
legg <legg@nospam.magma.ca> wrote:
On Tue, 20 May 2025 18:03:50 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I've been posting here for more than twenty years.
That started me wondering how long I have been posting here. I checked >> >back and my first <sci.electronic.design> post was 20 years and 4 months >> >ago.
I don't see anything 'saved' before 2004, here.
Wasn't there some kind of bleed-over into Google Groups?
I have an archive on my machine going back to about 2000, when I first >started using Usenet. Google was just a useful new search engine at
that time, not the ubiquitous, intrusive, data-devouring monster it has >since grown into.
Their charter used to include "Don't be evil" but that was deleted.
Evil turned out to be more profitable.
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair
1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it -
though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice
models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part
for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for
about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have used
them myself (to start a xenon arc lamp), but they wouldn't be useful here.
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair
1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it -
though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice
models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller -
part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for
about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator".
Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
Going from 1KV to 3.3v has interesting possibilities. The easy way is
a resistor and a zener. Efficiency about 0.3%.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice
models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller -
part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where >>> a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high
voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
john larkin <jl@glen--canyon.com> wrote:
[...]
Going from 1KV to 3.3v has interesting possibilities. The easy way is
a resistor and a zener. Efficiency about 0.3%.
Roughly 1W dissipation per mA , so if the current requirement isn't too
high, that is probably the most straightforward system with very little
to go wrong.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
That's a lot of extra complication for very little improvement, the
resistor still has to carry the full load current.
For a cult market you could use an 807 and tap the 3.3v off the cathode
bias resistor. (or better still, rectify the heater supply and use a
linear regulator but don't tell the customer).
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where >>> a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high
voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
On Thu, 22 May 2025 09:44:30 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
[...]
Going from 1KV to 3.3v has interesting possibilities. The easy way is
a resistor and a zener. Efficiency about 0.3%.
Roughly 1W dissipation per mA , so if the current requirement isn't too >high, that is probably the most straightforward system with very little
to go wrong.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
That's a lot of extra complication for very little improvement, the >resistor still has to carry the full load current.
For a cult market you could use an 807 and tap the 3.3v off the cathode >bias resistor. (or better still, rectify the heater supply and use a >linear regulator but don't tell the customer).
I never liked 807's. Ugly tubes.
john larkin <jl@glen--canyon.com> wrote:
On Thu, 22 May 2025 09:44:30 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
[...]
Going from 1KV to 3.3v has interesting possibilities. The easy way is
a resistor and a zener. Efficiency about 0.3%.
Roughly 1W dissipation per mA , so if the current requirement isn't too
high, that is probably the most straightforward system with very little
to go wrong.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
That's a lot of extra complication for very little improvement, the
resistor still has to carry the full load current.
For a cult market you could use an 807 and tap the 3.3v off the cathode
bias resistor. (or better still, rectify the heater supply and use a
linear regulator but don't tell the customer).
I never liked 807's. Ugly tubes.
Ah yes. For that market, appearance is everything.
A much better-looking bottle would be a PY81 but, although it is
specified to withstand a peak anode voltage of 7 kV, the maunfacturers
only allow that under cutoff conditions. It also uses a standard B9A
base, which is still easily obtainable.
On Thu, 22 May 2025 10:43:47 -0000 (UTC), piglet
<erichpwagner@hotmail.com> wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply
frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is >>>>>>> series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work >>>>>>> would be a reed relay, and they are slow and don't last long when >>>>>>> cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at >>>>> 3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>>>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V >>>> it could just increase the current and reduce voltage to the point where >>>> a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high
voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
I had a similar thought, posted just before I saw yours. Honest.
On 22/05/2025 8:43 pm, piglet wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a >>>>>>>>> 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>>> though
it's a much higher current part (10A) than the job needs (about >>>>>>>>> 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on >>>>>>>> supply
frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is >>>>>>> series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work >>>>>>> would be a reed relay, and they are slow and don't last long when >>>>>>> cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at >>>>> 3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx
generator".
Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V >>>> it could just increase the current and reduce voltage to the point
where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high
voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
That's an exact (if incomplete) description of the Baxandall Class-D oscillator.
It has got two two transistors and it is self-oscillating, and Jim
Williams did popularise it for driving CFL backlights. He never called
it a Baxandall oscillator, but that's exactly what his Linear Technology application notes AN45, AN49, AN51, AN55, AN61, and AN65 talked about.
On 22/05/2025 2:41 pm, Bill Sloman wrote:
On 22/05/2025 8:43 pm, piglet wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:The forward diode drop is inconsequential at 1kV, but inconvenient at >>>>>> 3.3V. And you'd need 250 stages in this application.
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a >>>>>>>>>> 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>>>> though
it's a much higher current part (10A) than the job needs
(about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on >>>>>>>>> supply
frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is >>>>>>>> series, and discharging them in parallel is one mode of current >>>>>>>> multiplication, but about the only kind of switch that would work >>>>>>>> would be a reed relay, and they are slow and don't last long when >>>>>>>> cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds >>>>>>>> for
about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element. >>>>>>
I've got AOE3. It's index doesn't point to any "reverse Marx
generator".
Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have >>>>>> used them myself (to start a xenon arc lamp), but they wouldn't be >>>>>> useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V >>>>> it could just increase the current and reduce voltage to the point
where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high >>>> voltage MOSFET, which clearly exist, even if Infineon is being slow to >>>> offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on >>>> the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
That's an exact (if incomplete) description of the Baxandall Class-D
oscillator.
It has got two two transistors and it is self-oscillating, and Jim
Williams did popularise it for driving CFL backlights. He never called
it a Baxandall oscillator, but that's exactly what his Linear
Technology application notes AN45, AN49, AN51, AN55, AN61, and AN65
talked about.
There is a big difference in the voltage stress seen by the transistors.
The half bridge exposes each to 1kV max, the push-pull to nearly double
(I think you quoted 1.6kV).
Baxandall topology was great for tape recorder erase/bias oscillator
kinda stuff at low supply voltages but at HV not such a great choice.
On Thu, 22 May 2025 16:50:25 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
On Thu, 22 May 2025 09:44:30 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
[...]
Going from 1KV to 3.3v has interesting possibilities. The easy way is >> >> a resistor and a zener. Efficiency about 0.3%.
Roughly 1W dissipation per mA , so if the current requirement isn't too >> >high, that is probably the most straightforward system with very little >> >to go wrong.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
That's a lot of extra complication for very little improvement, the
resistor still has to carry the full load current.
For a cult market you could use an 807 and tap the 3.3v off the cathode >> >bias resistor. (or better still, rectify the heater supply and use a
linear regulator but don't tell the customer).
I never liked 807's. Ugly tubes.
Ah yes. For that market, appearance is everything.
A much better-looking bottle would be a PY81 but, although it is
specified to withstand a peak anode voltage of 7 kV, the maunfacturers
only allow that under cutoff conditions. It also uses a standard B9A
base, which is still easily obtainable.
A great audiophool prodcut would be a power amp with a pair of 833's
and lots of custom transformers and oil caps and things. Figure about
100 lbs and $30K.
john larkin <jl@glen--canyon.com> wrote:
On Thu, 22 May 2025 16:50:25 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
On Thu, 22 May 2025 09:44:30 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
john larkin <jl@glen--canyon.com> wrote:
[...]
Going from 1KV to 3.3v has interesting possibilities. The easy way is >> >> >> a resistor and a zener. Efficiency about 0.3%.
Roughly 1W dissipation per mA , so if the current requirement isn't too >> >> >high, that is probably the most straightforward system with very little >> >> >to go wrong.
More efficient would be a resistor and a zener and then a buck
switcher. 5% maybe.
That's a lot of extra complication for very little improvement, the
resistor still has to carry the full load current.
For a cult market you could use an 807 and tap the 3.3v off the cathode >> >> >bias resistor. (or better still, rectify the heater supply and use a
linear regulator but don't tell the customer).
I never liked 807's. Ugly tubes.
Ah yes. For that market, appearance is everything.
A much better-looking bottle would be a PY81 but, although it is
specified to withstand a peak anode voltage of 7 kV, the maunfacturers
only allow that under cutoff conditions. It also uses a standard B9A
base, which is still easily obtainable.
A great audiophool prodcut would be a power amp with a pair of 833's
and lots of custom transformers and oil caps and things. Figure about
100 lbs and $30K.
I have recently been told of one - the output transformer alone cost UKP >9,000 and was wound with silver wire (probably spun by virgins at
midnight).
It amuses me that there is great prestige value put on using triodes
"with no negative feedback", completely ignoring the fact that triodes
have built-in non-linear negative feedback because of the influence of
the anode potential on the grid-cathode potential gradient. A triode
with the negative feedback removed is called a 'Pentode' ..but they are >condemned for being non-linear and "unmusical".
Bill Sloman <bill.sloman@ieee.org> wrote:
On 22/05/2025 11:20 am, KevinJ93 wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice >>>>>>>> models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - >>>>>>>> part for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have
used them myself (to start a xenon arc lamp), but they wouldn't be
useful here.
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where >>> a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The Baxandall inverter looks as if it would work with sufficiently high
voltage MOSFET, which clearly exist, even if Infineon is being slow to
offer a Spice model to let me simulate it.
It's a pretty simple circuit, even if the component parts look to be on
the expensive side - coping with even 1kV costs money.
Maybe a simple self oscillating two transistor half bridge as in CFL
ballasts of a few decades ago?
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote:
The drain swing is actually 1.67 times the supply voltage, but it does >>>> need two switching devices and a specially wound transformer (and we
know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>> be grateful for your insights into a cheaper alternative. I can't think >>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A ccfl transformer is ideal for the HV step-down application, and dirt
cheap is a side benefit.
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
It's not the sort of component that a search engine will find for you.
A manufacturer and a part number would be helpful.
On Wed, 21 May 2025 03:25:11 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote: >>>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>>> need two switching devices and a specially wound transformer (and we >>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A ccfl transformer is ideal for the HV step-down application, and dirt
cheap is a side benefit.
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
It's not the sort of component that a search engine will find for you.
A manufacturer and a part number would be helpful.
Try asking Grok, Bill. Or else your preferred AI assistant. Works for
me.
On Mon, 26 May 2025 11:17:05 +0100, Cursitor Doom
<cd6699@notformail.com> wrote:
On Wed, 21 May 2025 03:25:11 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote: >>>>>>
A ccfl transformer is ideal for the HV step-down application, and dirt >>>> cheap is a side benefit.The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>>
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
It's not the sort of component that a search engine will find for you.
A manufacturer and a part number would be helpful.
Try asking Grok, Bill. Or else your preferred AI assistant. Works for
me.
He could strain his imagination to its limits and google
ccfl transformer
And then he could try designing electronics.
On Wed, 21 May 2025 03:25:11 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote: >>>>>
The drain swing is actually 1.67 times the supply voltage, but it does >>>>> need two switching devices and a specially wound transformer (and we >>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'.
A ccfl transformer is ideal for the HV step-down application, and dirt
cheap is a side benefit.
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
It's not the sort of component that a search engine will find for you.
A manufacturer and a part number would be helpful.
Try asking Grok, Bill. Or else your preferred AI assistant. Works for
me.
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
The drain swing is actually 1.67 times the supply voltage, but it does
Where does 1.67 come from?
On Tue, 27 May 2025 01:07:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 26/05/2025 4:20 am, JM wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
The drain swing is actually 1.67 times the supply voltage, but it does
Where does 1.67 come from?
Integrate a series of half-sine peaks that get to 1.67V and the voltage
averages to about 1V.
You can do it as purely mathematical exercise, and I did it years ago,
and that's roughly the result I got.
There's a voltage drop across the switching FET that's on and the
Baxandall circuit doesn't product perfect half-sine waves, so it hasn't
got a lot to do with precise reality, but it's good enough for
preliminary design.
If senile dementia hasn't set in too far I could probably do it again.
Yes, but that's the centre tap voltage. Due to the autotransformer
action the stress across the off transistor will be twice that, or
1000*PI in this application. The 1700 volt device under consideration
isn't up to the task.
On 26/05/2025 8:17 pm, Cursitor Doom wrote:
On Wed, 21 May 2025 03:25:11 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote: >>>>>>
A ccfl transformer is ideal for the HV step-down application, and dirt >>>> cheap is a side benefit.The drain swing is actually 1.67 times the supply voltage, but it does >>>>>> need two switching devices and a specially wound transformer (and we >>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50)
transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>>
They often have several windings, which helps build oscillators. More
details might involve using a search engine.
It's not the sort of component that a search engine will find for you.
A manufacturer and a part number would be helpful.
Try asking Grok, Bill. Or else your preferred AI assistant. Works for
me.
AI does produce quite a bit of nonsense, and we know how
enthusiastically you embrace implausible nonsense.
Some of us are more interested in objectively verifiable reality.
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair
1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it -
though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice
models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part >>>>>> for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for
about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator".
Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have used
them myself (to start a xenon arc lamp), but they wouldn't be useful here. >>
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
On Tue, 27 May 2025 00:49:48 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 26/05/2025 8:17 pm, Cursitor Doom wrote:
On Wed, 21 May 2025 03:25:11 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 21/05/2025 12:04 am, john larkin wrote:<...>
On Mon, 19 May 2025 09:33:28 -0400, legg <legg@nospam.magma.ca> wrote: >>>>>>>
A ccfl transformer is ideal for the HV step-down application, and dirt >>>>> cheap is a side benefit.The drain swing is actually 1.67 times the supply voltage, but it does >>>>>>> need two switching devices and a specially wound transformer (and we >>>>>>> know how reluctant you are to design them or get them made).
It is probably going to be too expensive for the application, and we'd >>>>>>> be grateful for your insights into a cheaper alternative. I can't think >>>>>>> of one.
I'd keep it simple and repurpose a backwards commodity CCFL ($0.50) >>>>>> transformer, in a low frequency (20-50KHz) buck regulator 'of sorts'. >>>>>
They often have several windings, which helps build oscillators. More >>>>> details might involve using a search engine.
It's not the sort of component that a search engine will find for you. >>>>
A manufacturer and a part number would be helpful.
Try asking Grok, Bill. Or else your preferred AI assistant. Works for
me.
AI does produce quite a bit of nonsense, and we know how
enthusiastically you embrace implausible nonsense.
Some of us are more interested in objectively verifiable reality.
Well, it does at times produce a lot of nonsense, I grant you.
However, it would only cost a few moments of your time to try and you
might well be pleasantly surprised. It's getting better and better as
time goes by.
On Wed, 21 May 2025 18:20:25 -0700, KevinJ93 <kevin_es@whitedigs.com>
wrote:
On 5/21/25 12:20 AM, Bill Sloman wrote:
On 21/05/2025 3:47 am, KevinJ93 wrote:
On 5/20/25 1:46 AM, Bill Sloman wrote:
On 20/05/2025 1:13 am, Liz Tuddenham wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair >>>>>>> 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - >>>>>>> though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice
models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part >>>>>>> for
which there is an LTSpice model?
How about a piezoelectric transformer run in reverse?
The piezoelectric transformer is an interesting idea.
Neon tubes illuminating a solar cell?
Neither is all that efficient.
Capacitive divider using a spare core in the
mains supply lead as one plate of the capacitor? (Depending on supply >>>>>> frequency and required output current.)
I can't see how that could work. Charging up lots of capacitor is
series, and discharging them in parallel is one mode of current
multiplication, but about the only kind of switch that would work
would be a reed relay, and they are slow and don't last long when
cycled fast.
Dry reeds are good for 10 million closures, mercury-wetted reeds for >>>>> about 100 million, and neither is all that cheap or compact.
The Art of Engineering #3 (I think) - describes a "Reverse Marx
Generator" that does exactly that (charging caps in series and
discharging in parallel). It uses diodes as the switching element.
The forward diode drop is inconsequential at 1kV, but inconvenient at
3.3V. And you'd need 250 stages in this application.
I've got AOE3. It's index doesn't point to any "reverse Marx generator". >>> Google search throws up links, but nothing useful.
The classic Marx generator uses spark gaps as its switches. I have used
them myself (to start a xenon arc lamp), but they wouldn't be useful here. >>>
Sorry -- it is on page 440 of the X-chapters, not AOE3.
The reverse Marx generator doesn't need to go all the way down to 3.3V
it could just increase the current and reduce voltage to the point where
a conventional converter (such as a flyback) can be used without
excessive voltage devices being used.
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
So use a resistor and a zener to make 36 volts and dump it here:
https://www.digikey.com/en/products/detail/mornsun-america-llc/K78L03-1000R3/16571443
That will be about 3% efficient and cost under $2.
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
On 27/05/2025 9:09 am, john larkin wrote:
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
[...]
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
On Tue, 27 May 2025 14:16:11 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
A 3.3v real zener will probably leak more than 10uA. Low voltage
zeners are awful.
And he wants 3 mA out... I think.
[...]
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
Bill was the confused person.
The problem gets much more interesting with 10 uA in and 99%
efficiency requirement.
A Baxandall isn't going pull microamps at 1 KV.
On 27/05/2025 11:46 pm, john larkin wrote:
On Tue, 27 May 2025 14:16:11 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3 >>>>> ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
A 3.3v real zener will probably leak more than 10uA. Low voltage
zeners are awful.
And he wants 3 mA out... I think.
The guy I was talking to had 10uA at 1kV, and wanted a 3.3V output. 1mW
at 3.3V is 3mA. The 3ma is the upper limit the circuit could supply.
[...]
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
You managed it.
Bill was the confused person.
John Larkin does like to think that.
The problem gets much more interesting with 10 uA in and 99%
efficiency requirement.
There never was an efficiency requirement. 50% would have been nice.
A Baxandall isn't going pull microamps at 1 KV.
Keeping a resonant tank resonating at a couple of kV is going to use up
power in the winding resistance. I think I can get 245H out of RM14
core. If we can keep the parallel capacitance down to 25pF that would >resonate at 2kHz and the reactive impedance would be 3 Mohm, giving a
peak current 0f 1mA. The resistance of the winding is going to be about
480R, so I^2.R is 500uW, or 0.5uA at 1kV.
A properly designed Baxandall might well pull less than 1uA if lightly >loaded.
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>> it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>> which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a
1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
On Wed, 28 May 2025 00:28:12 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 27/05/2025 11:46 pm, john larkin wrote:
On Tue, 27 May 2025 14:16:11 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3 >>>>>> ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
A 3.3v real zener will probably leak more than 10uA. Low voltage
zeners are awful.
And he wants 3 mA out... I think.
The guy I was talking to had 10uA at 1kV, and wanted a 3.3V output. 1mW
at 3.3V is 3mA. The 3ma is the upper limit the circuit could supply.
Geez, check your work before you post it. 3.3v * 3 mA is 10 mW.
I have a few kids that I'm teaching to design electronics. They
already have EE degrees.
One of the fundamental concepts: check your work.
[...]
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
You managed it.
Bill was the confused person.
John Larkin does like to think that.
The problem gets much more interesting with 10 uA in and 99%
efficiency requirement.
There never was an efficiency requirement. 50% would have been nice.
A Baxandall isn't going pull microamps at 1 KV.
Keeping a resonant tank resonating at a couple of kV is going to use up
power in the winding resistance. I think I can get 245H out of RM14
core. If we can keep the parallel capacitance down to 25pF that would
resonate at 2kHz and the reactive impedance would be 3 Mohm, giving a
peak current 0f 1mA. The resistance of the winding is going to be about
480R, so I^2.R is 500uW, or 0.5uA at 1kV.
A properly designed Baxandall might well pull less than 1uA if lightly
loaded.
Build it.
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>> which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a
1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
Finally, a purpose ...
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>> which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a
1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
I don't think that John Larkin needs my help to get confused.
Finally, a purpose ...
The first line of my original post was.
"I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V. "
That's been the purpose all along.
On Tue, 27 May 2025 02:43:41 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 27/05/2025 1:57 am, JM wrote:
On Tue, 27 May 2025 01:07:36 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 26/05/2025 4:20 am, JM wrote:
On Mon, 19 May 2025 12:23:54 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 19/05/2025 12:15 am, john larkin wrote:
On Sun, 18 May 2025 18:11:58 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>>>> wrote:
I have found a 4.5KV MOSFET, the IXYS IXTT02450HV which could survive in
the standard Baxandall configuration.
It's $US45.24 each in small volume (which really is excessively
expensive), and I've asked for Spice model, but if Infineon is anything
to go by, I'm not going to get it anytime soon.
If either Spice model shows up I'll try and put a simulation together.
It has nearly got to the point where I should try and bodge a MOSFET
model that I have got access to into something that would fit one or
other data sheet, but that's hard work, and my model isn't going to be
all that trustworthy.
You are probably best with bipolar. If you use a push-pull current
fed half bridge the transistor breakdown rating will be 500*PI (1.57
kV). Since the off transistor will have a reverse bias of a few volts
on it's base it's breakdown voltage will (typically) be a few hundred
volts greater than it's Vceo spec. The 2sc4634/4636 would suffice.
On Wed, 28 May 2025 21:03:03 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net>
wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV >>>>>>> MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though >>>>>>> it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models, >>>>>>> but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for >>>>>>> which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a >>>> 1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
I don't think that John Larkin needs my help to get confused.
Finally, a purpose ...
The first line of my original post was.
"I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V. "
That's been the purpose all along.
Your (still confused and unresolved) specifications opened up a wide
range of possible implementations. Thanks.
On 29/05/2025 12:26 am, john larkin wrote:
On Wed, 28 May 2025 21:03:03 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com>
wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net> >>>>> wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a >>>>> 1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
I don't think that John Larkin needs my help to get confused.
Finally, a purpose ...
The first line of my original post was.
"I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V. "
That's been the purpose all along.
Your (still confused and unresolved) specifications opened up a wide
range of possible implementations. Thanks.
Since I've now at least got a PSpice model for the IXTH1N450HV 4.5KV
FET, I can - with luck - get on with being confused by an actual (if >simulated circuit). Typical Ciss is depressingly high at 1700pF.
The higher current (but lower voltage) Infineon IMWH170R450M1 has a
typical Ciss of 506pF and is cheaper than $US45 IXYS part.
You may find the specification to be confused and unresolved. I haven't
spelt it out in detail because - as the subject line spells out - that's
not what I'm here for. As far as I can see I've been consistent about
what I believe my contact is seeking, and what you are complaining about
is the way you have misconstrued passing comments.
On Thu, 29 May 2025 02:24:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 29/05/2025 12:26 am, john larkin wrote:
On Wed, 28 May 2025 21:03:03 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com> >>>>> wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net> >>>>>> wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA). >>>>>>>>>
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a >>>>>> 1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to
consider. We can thank Sloman for being confused.
I don't think that John Larkin needs my help to get confused.
Finally, a purpose ...
The first line of my original post was.
"I'm looking at a problem where somebody wants to step down a 1kV low
current source to 3.3V. "
That's been the purpose all along.
Your (still confused and unresolved) specifications opened up a wide
range of possible implementations. Thanks.
Since I've now at least got a PSpice model for the IXTH1N450HV 4.5KV
FET, I can - with luck - get on with being confused by an actual (if
simulated circuit). Typical Ciss is depressingly high at 1700pF.
The higher current (but lower voltage) Infineon IMWH170R450M1 has a
typical Ciss of 506pF and is cheaper than $US45 IXYS part.
You may find the specification to be confused and unresolved. I haven't
spelt it out in detail because - as the subject line spells out - that's
not what I'm here for. As far as I can see I've been consistent about
what I believe my contact is seeking, and what you are complaining about
is the way you have misconstrued passing comments.
What are the requirements? 1 mA, 3 mA, 1 mW, 10 mW, some microamps,
where? There have been all sorts of numbers.
Does cost matter?
On 29/05/2025 3:56 am, john larkin wrote:
On Thu, 29 May 2025 02:24:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 29/05/2025 12:26 am, john larkin wrote:
On Wed, 28 May 2025 21:03:03 +1000, Bill Sloman <bill.sloman@ieee.org> >>>> wrote:
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com> >>>>>> wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net> >>>>>>> wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
I'm looking at a problem where somebody wants to step down a 1kV low >>>>>>>>>> current source to 3.3V.
The Baxandall class-D oscillator could do it, but it needs a pair 1.7kV
MOSFETs for the job. The Infineon SiC IMH170R450M1 would do it - though
it's a much higher current part (10A) than the job needs (about 1mA).
I've dived into the Infineon rabbit-hole which promises LTSpice models,
but wasn't able to find one.
Does anybody know of a similar - ideally cheaper and smaller - part for
which there is an LTSpice model?
Maybe use an electrostatic motor driving a small generator!
Maybe DON'T FEED THE TROLL?
It is an interesting problem, designing a logic supply that runs off a >>>>>>> 1 KV DC supply. Even when the requirements are confused.
Actually, the uncertainty opens up more circuit possibilities to >>>>>>> consider. We can thank Sloman for being confused.
I don't think that John Larkin needs my help to get confused.
Finally, a purpose ...
The first line of my original post was.
"I'm looking at a problem where somebody wants to step down a 1kV low >>>>> current source to 3.3V. "
That's been the purpose all along.
Your (still confused and unresolved) specifications opened up a wide
range of possible implementations. Thanks.
Since I've now at least got a PSpice model for the IXTH1N450HV 4.5KV
FET, I can - with luck - get on with being confused by an actual (if
simulated circuit). Typical Ciss is depressingly high at 1700pF.
The higher current (but lower voltage) Infineon IMWH170R450M1 has a
typical Ciss of 506pF and is cheaper than $US45 IXYS part.
You may find the specification to be confused and unresolved. I haven't
spelt it out in detail because - as the subject line spells out - that's >>> not what I'm here for. As far as I can see I've been consistent about
what I believe my contact is seeking, and what you are complaining about >>> is the way you have misconstrued passing comments.
What are the requirements? 1 mA, 3 mA, 1 mW, 10 mW, some microamps,
where? There have been all sorts of numbers.
The basic idea is that my contact has 1kV source capable of delivering
about 10uA - 10mW - and wants to use it to power some logic from a 3.3V
power rail. He'd like better than 50% efficiency, so presumaby he wants >something approaching 1.5mA. About the only other number I recall
posting was the idea that a switching MOSFET might need to handle up to
1mA rather than the 1A the IXTH1N450HV can manage or the 10A the
Infineon part offers.
I've now had an interesting an potentially patentable idea that I'm
obviously not going to post on a public forum. Like most patentable
ideas it is unlikely to actually work, let alone be be practicable.
Does cost matter?
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of
money for a few devices, or if there is he hasn't mentioned it to me
(and probably wouldn't) if there was.
On Thu, 29 May 2025 16:12:52 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 29/05/2025 3:56 am, john larkin wrote:
On Thu, 29 May 2025 02:24:01 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 29/05/2025 12:26 am, john larkin wrote:
On Wed, 28 May 2025 21:03:03 +1000, Bill Sloman <bill.sloman@ieee.org> >>>>> wrote:
On 28/05/2025 3:08 am, Joe Gwinn wrote:
On Tue, 27 May 2025 07:53:12 -0700, john larkin <jl@glen--canyon.com> >>>>>>> wrote:
On Tue, 27 May 2025 10:02:27 -0400, Joe Gwinn <joegwinn@comcast.net> >>>>>>>> wrote:
On Tue, 27 May 2025 20:32:49 +1000, Chris Jones
<lugnut808@spam.yahoo.com> wrote:
On 18/05/2025 6:11 pm, Bill Sloman wrote:
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of
money for a few devices, or if there is he hasn't mentioned it to me
(and probably wouldn't) if there was.
I can imagine some cheap approaches if something like 25% efficiency
were acceptable.
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of
money for a few devices, or if there is he hasn't mentioned it to me
(and probably wouldn't) if there was.
I can imagine some cheap approaches if something like 25% efficiency
were acceptable.
I finally got a Pspice model for the IXTH02N450HV out of IXYS and - with
a bit of help from John May - got the part working in a simulation.
I did managed to get 1mA out at 3.3V but I was drawing 12.5uA out of the
1kV source, so only about 30% efficiency. The two transistor are $US45
each, so it's not a cheap circuit. It only runs at 2.5kHz even with
pretty optimistic parallel capacitances for the high impedance windings.
There a 40kHz ripple on the current drawn from the 1kV suuply at about
115uA peak to peak, so that may be where the extra current is being used up.
<snip>
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of
money for a few devices, or if there is he hasn't mentioned it to me
(and probably wouldn't) if there was.
I can imagine some cheap approaches if something like 25% efficiency
were acceptable.
I finally got a Pspice model for the IXTH02N450HV out of IXYS and - with
a bit of help from John May - got the part working in a simulation.
I did managed to get 1mA out at 3.3V but I was drawing 12.5uA out of the
1kV source, so only about 30% efficiency. The two transistor are $US45
each, so it's not a cheap circuit. It only runs at 2.5kHz even with
pretty optimistic parallel capacitances for the high impedance windings.
There a 40kHz ripple on the current drawn from the 1kV suuply at about
115uA peak to peak, so that may be where the extra current is being used up.
So it's 3V3 at 1mA, after all.
2W resistor and a zener diode.
On 3/06/2025 2:42 am, legg wrote:
<snip>
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of
money for a few devices, or if there is he hasn't mentioned it to me >>>>> (and probably wouldn't) if there was.
I can imagine some cheap approaches if something like 25% efficiency
were acceptable.
I finally got a Pspice model for the IXTH02N450HV out of IXYS and - with >>> a bit of help from John May - got the part working in a simulation.
I did managed to get 1mA out at 3.3V but I was drawing 12.5uA out of the >>> 1kV source, so only about 30% efficiency. The two transistor are $US45
each, so it's not a cheap circuit. It only runs at 2.5kHz even with
pretty optimistic parallel capacitances for the high impedance windings. >>>
There a 40kHz ripple on the current drawn from the 1kV suuply at about
115uA peak to peak, so that may be where the extra current is being used up.
So it's 3V3 at 1mA, after all.
2W resistor and a zener diode.
The 1kV source is good for about 10uA. Do pay attention.
On Tue, 3 Jun 2025 11:58:30 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 3/06/2025 2:42 am, legg wrote:
<snip>
He does want it to be inexpensive. There doesn't seem to be any
specialised market where a few customers can afford to pay a lot of >>>>>> money for a few devices, or if there is he hasn't mentioned it to me >>>>>> (and probably wouldn't) if there was.
I can imagine some cheap approaches if something like 25% efficiency >>>>> were acceptable.
I finally got a Pspice model for the IXTH02N450HV out of IXYS and - with >>>> a bit of help from John May - got the part working in a simulation.
I did managed to get 1mA out at 3.3V but I was drawing 12.5uA out of the >>>> 1kV source, so only about 30% efficiency. The two transistor are $US45 >>>> each, so it's not a cheap circuit. It only runs at 2.5kHz even with
pretty optimistic parallel capacitances for the high impedance windings. >>>>
There a 40kHz ripple on the current drawn from the 1kV suuply at about >>>> 115uA peak to peak, so that may be where the extra current is being used up.
So it's 3V3 at 1mA, after all.
2W resistor and a zener diode.
The 1kV source is good for about 10uA. Do pay attention.
If you'd answered those questions accurately, when originally asked,
you would have had my attention.
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
[...]
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
On Tue, 27 May 2025 14:16:11 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
Bill Sloman <bill.sloman@ieee.org> wrote:
On 27/05/2025 9:09 am, john larkin wrote:
[...]
The specs, as far as I can tell, suggest 1KV at 1 ma in and 3.3v at 3
ma out. The required efficiency is then 1%.
Actually 1kV at 10uA in.
Good grief! A 10-megohm quarter watt resistor with a zener diode is
the obvious answer.
A 3.3v zener will probably leak more than 10uA. Low voltage zeners are
awful.
And he wants 3 mA out... I think.
Misunderstanding the constraints can lead people to propose
inappropriate solutions.
How can anyone misunderstand something they have never been told?
Bill was the confused person.
The problem gets much more interesting with 10 uA in and 99%
efficiency requirement.
A Baxandall isn't going pull microamps at 1 KV.
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