One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
But that got me thinking about audio oscillators.
Imagine three blocks A B and C in a loop. B and C are opamp inverting integrators, and A is a plain inverter. Power it up an nothing
happens. Power it up with some initial condition voltage on B and it oscillates practically forever at that amplitude.
In real iife, one adds a bit of phase lag to A and you get an
increasing amplitude sine wave, and then you need an active gain
control loop to avoid clipping.
So use hi-K ceramic caps in A and tune the servo loop by varying the
bias on the caps. Use two caps in series and bias the midpoint to
minimize distortion. Take the output from C, which is doubly lowpass
filtered from any distortion in A.
There might be a circuit where the cap nonlinearity alone was the gain limiting effect.
This would be tough to Spice because it needs nonlinear caps, and
because Spice math errors pile up bad when simming things like this,
and it would run glacially slow.
On 2025-08-02 7:11 a.m., john larkin wrote:
One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
What page of AoE3?
Closest I can find is a line on a chart reference to High-K Ceramic caps
on page 301 (figure 5.4).
Page 28 section 1.4.5 Not Quite Perfect... talks about memory effect,
but no warnings...
Maybe this is in AoE-X?
John :-#)#
On 3/08/2025 12:11 am, john larkin wrote:
One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
But that got me thinking about audio oscillators.
Imagine three blocks A B and C in a loop. B and C are opamp inverting
integrators, and A is a plain inverter. Power it up an nothing
happens. Power it up with some initial condition voltage on B and it
oscillates practically forever at that amplitude.
In real iife, one adds a bit of phase lag to A and you get an
increasing amplitude sine wave, and then you need an active gain
control loop to avoid clipping.
So use hi-K ceramic caps in A and tune the servo loop by varying the
bias on the caps. Use two caps in series and bias the midpoint to
minimize distortion. Take the output from C, which is doubly lowpass
filtered from any distortion in A.
There might be a circuit where the cap nonlinearity alone was the gain
limiting effect.
This would be tough to Spice because it needs nonlinear caps, and
because Spice math errors pile up bad when simming things like this,
and it would run glacially slow.
It's a bad idea. Audio oscillators are supposed to produce clean sine
waves, and hi-K ceramic caps have a voltage dependent capacitance.
As a sine wave goes up to peak voltage and back again, equal changes in >voltage will produce varying chunks of charge, and you won't have a sine
wave of current.
We've had a couple of threads on sine wave oscillators, and you don't
seem to have learned anything from any of them.
On Sun, 3 Aug 2025 01:29:40 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 3/08/2025 12:11 am, john larkin wrote:
One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
But that got me thinking about audio oscillators.
Imagine three blocks A B and C in a loop. B and C are opamp inverting
integrators, and A is a plain inverter. Power it up an nothing
happens. Power it up with some initial condition voltage on B and it
oscillates practically forever at that amplitude.
In real iife, one adds a bit of phase lag to A and you get an
increasing amplitude sine wave, and then you need an active gain
control loop to avoid clipping.
So use hi-K ceramic caps in A and tune the servo loop by varying the
bias on the caps. Use two caps in series and bias the midpoint to
minimize distortion. Take the output from C, which is doubly lowpass
filtered from any distortion in A.
There might be a circuit where the cap nonlinearity alone was the gain
limiting effect.
This would be tough to Spice because it needs nonlinear caps, and
because Spice math errors pile up bad when simming things like this,
and it would run glacially slow.
It's a bad idea. Audio oscillators are supposed to produce clean sine
waves, and hi-K ceramic caps have a voltage dependent capacitance.
Gosh. I never knew that.
As a sine wave goes up to peak voltage and back again, equal changes in
voltage will produce varying chunks of charge, and you won't have a sine
wave of current.
We've had a couple of threads on sine wave oscillators, and you don't
seem to have learned anything from any of them.
Lots of people who have no ideas, are hostile to ideas.
On 3/08/2025 1:48 am, john larkin wrote:
On Sun, 3 Aug 2025 01:29:40 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 3/08/2025 12:11 am, john larkin wrote:
One of my kids desiged an 8-channel high voltage pulse generator. We
don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits
using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic
cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
But that got me thinking about audio oscillators.
Imagine three blocks A B and C in a loop. B and C are opamp inverting
integrators, and A is a plain inverter. Power it up an nothing
happens. Power it up with some initial condition voltage on B and it
oscillates practically forever at that amplitude.
In real iife, one adds a bit of phase lag to A and you get an
increasing amplitude sine wave, and then you need an active gain
control loop to avoid clipping.
So use hi-K ceramic caps in A and tune the servo loop by varying the
bias on the caps. Use two caps in series and bias the midpoint to
minimize distortion. Take the output from C, which is doubly lowpass
filtered from any distortion in A.
There might be a circuit where the cap nonlinearity alone was the gain >>>> limiting effect.
This would be tough to Spice because it needs nonlinear caps, and
because Spice math errors pile up bad when simming things like this,
and it would run glacially slow.
It's a bad idea. Audio oscillators are supposed to produce clean sine
waves, and hi-K ceramic caps have a voltage dependent capacitance.
Gosh. I never knew that.
Of course you did, but you've never bothered to think about the implications.
As a sine wave goes up to peak voltage and back again, equal changes in
voltage will produce varying chunks of charge, and you won't have a sine >>> wave of current.
This should have been an obvious implication, which you don't seem to have noticed.
We've had a couple of threads on sine wave oscillators, and you don't
seem to have learned anything from any of them.
Lots of people who have no ideas, are hostile to ideas.
I have plenty of ideas, and I'm not in the least hostile to good ideas. I am hostile to bad ideas.
Their proponents have been known to waste a lot of time and money following them up - not just their own, but other people's as
well.
Your junior engineers will have been trained not to say boo! to the goose.
--
Bill Sloman, Sydney
"Bill Sloman" <bill.sloman@ieee.org> wrote in message news:106ms0q$1ek10$1@dont-email.me...
On 3/08/2025 1:48 am, john larkin wrote:
On Sun, 3 Aug 2025 01:29:40 +1000, Bill Sloman <bill.sloman@ieee.org>
wrote:
On 3/08/2025 12:11 am, john larkin wrote:
One of my kids desiged an 8-channel high voltage pulse generator. We >>>>> don't know what it's for and the customer won't say, so we guess.
It's a mess of classic hairball async logic. There is a 1 Hz test
oscillator and a lockout timer one-shot. He did both with RC circuits >>>>> using 22 uF ceramic caps. Timings were off because of cap
nonlinearity, so I had to deliver a group lecture about hi-K ceramic >>>>> cap behavior.
A line in AoE3 says "Don't even THINK about using high-K caps in
timing circuits."
But that got me thinking about audio oscillators.
Imagine three blocks A B and C in a loop. B and C are opamp inverting >>>>> integrators, and A is a plain inverter. Power it up an nothing
happens. Power it up with some initial condition voltage on B and it >>>>> oscillates practically forever at that amplitude.
In real iife, one adds a bit of phase lag to A and you get an
increasing amplitude sine wave, and then you need an active gain
control loop to avoid clipping.
So use hi-K ceramic caps in A and tune the servo loop by varying the >>>>> bias on the caps. Use two caps in series and bias the midpoint to
minimize distortion. Take the output from C, which is doubly lowpass >>>>> filtered from any distortion in A.
There might be a circuit where the cap nonlinearity alone was the gain >>>>> limiting effect.
This would be tough to Spice because it needs nonlinear caps, and
because Spice math errors pile up bad when simming things like this, >>>>> and it would run glacially slow.
It's a bad idea. Audio oscillators are supposed to produce clean sine
waves, and hi-K ceramic caps have a voltage dependent capacitance.
Gosh. I never knew that.
Of course you did, but you've never bothered to think about the implications.
As a sine wave goes up to peak voltage and back again, equal changes in >>>> voltage will produce varying chunks of charge, and you won't have a sine >>>> wave of current.
This should have been an obvious implication, which you don't seem to have noticed.
We've had a couple of threads on sine wave oscillators, and you don't
seem to have learned anything from any of them.
Lots of people who have no ideas, are hostile to ideas.
I have plenty of ideas, and I'm not in the least hostile to good ideas. I am hostile to bad ideas.
But you have bad ideas yourself.
An example might be the sinewave oscillator circuit you produced some time ago.
It had at least four times as many components as anything produced by JM and much worse performance.
You then told me in a subsequent thread that I didn't like ferrite filters.
This is also ridiculous. I will use them when they are needed.
You will, of course, tell me that I don't know when they are needed but that's just another fantasy of yours.
Their proponents have been known to waste a lot of time and money following them up - not just their own, but other people's as
well.
There would likely never have been any such thing as Trinitron if a lot of time and money hadn't been wasted on:
https://en.wikipedia.org/wiki/Chromatron
If you'd been there at the time they could have saved a lot of money but I guess you don't speak Japanese.
Your junior engineers will have been trained not to say boo! to the goose.
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