For a project, I was wanting to make some small electronic cards that slide into sockets on a backplane, and then wire them together on the
backplane. I want the freedom to redo the wiring on the backplane
without having to reprint a new backplane. Do I have to find some old wire-wrapped backplane from the 1970s, or is there some kind of modern
— and ideally inexpensive — approach to this sort of thing? Maybe I just need the right kind of sockets mounted on a normal PCB, and then wire
wrap on the back side of those...?

I was thinking like 10 or so pins per card, though maybe I could use
quad chips instead for my modules and go with something like 40 pins.

It is not a data bus — purely analog — so I'm not looking for some kind
of data bus design.

--
Christopher Howard

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Christopher Howard <christopher@librehacker.com> wrote:

For a project, I was wanting to make some small electronic cards that slide into sockets on a backplane, and then wire them together on the
backplane. I want the freedom to redo the wiring on the backplane
without having to reprint a new backplane. Do I have to find some old wire-wrapped backplane from the 1970s, or is there some kind of modern
— and ideally inexpensive — approach to this sort of thing? Maybe I just need the right kind of sockets mounted on a normal PCB, and then wire
wrap on the back side of those...?

I was thinking like 10 or so pins per card, though maybe I could use
quad chips instead for my modules and go with something like 40 pins.

It is not a data bus — purely analog — so I'm not looking for some kind of data bus design.

Backplane systems are pretty retro at this point, apart from a few things
like VXI.

The last one I designed was around 1994, and that was a proof-of-concept prototype.

The cost, size, unreliability, and general clunkiness of backplane systems should be considered. I still build a lot of analog protos, but offshore
PCBAs are pretty cheap, so I only hand-wire them when I’m in a hurry.

What are you building?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics

--- SoupGate-Win32 v1.05
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On Tue, 27 May 2025 14:51:16 -0800, Christopher Howard <christopher@librehacker.com> wrote:

For a project, I was wanting to make some small electronic cards that slide >into sockets on a backplane, and then wire them together on the
backplane. I want the freedom to redo the wiring on the backplane
without having to reprint a new backplane. Do I have to find some old >wire-wrapped backplane from the 1970s, or is there some kind of modern
— and ideally inexpensive — approach to this sort of thing? Maybe I just
need the right kind of sockets mounted on a normal PCB, and then wire
wrap on the back side of those...?

I was thinking like 10 or so pins per card, though maybe I could use
quad chips instead for my modules and go with something like 40 pins.

It is not a data bus — purely analog — so I'm not looking for some kind
of data bus design.

Here's a box with boards that plug into a backplane.

https://www.dropbox.com/scl/fi/43dl9eoja8gr0j0wqox56/P940_FA_2.jpg?rlkey=n3s4ycq3cpnxwx7d6l8jbxm50&raw=1

The connectors are 32-pin DINs. They come in all sorts of sizes and configurations and some have wrappable tails.

I remember wire-wrap. It was awful for digital busses but might be OK
for the analog thing you are doing.

You could do a PCB for the bus, to hold things together and do the
power and grounds, and let the connector tails poke up for wrapping.

That bus above has 10 grounds and 7 pins of +48V per module, from that
kilowatt power supply.

--- SoupGate-Win32 v1.05
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On 5/27/2025 3:51 PM, Christopher Howard wrote:

For a project, I was wanting to make some small electronic cards that slide into sockets on a backplane, and then wire them together on the
backplane.

How are you planning on supporting these cards? What sort of
masses involved? Any connections to the opposite end of the card
(that would add to the stress on such a "socket")?

I want the freedom to redo the wiring on the backplane
without having to reprint a new backplane. Do I have to find some old wire-wrapped backplane from the 1970s, or is there some kind of modern
— and ideally inexpensive — approach to this sort of thing? Maybe I just need the right kind of sockets mounted on a normal PCB, and then wire
wrap on the back side of those...?

Are you certain that (analog!) signal integrity won't be an issue
with this approach? The frequencies and signal levels involved
(as you likely will be severely constrained as to HOW a signal can
be routed from "socket A" to "socket F")

I was thinking like 10 or so pins per card, though maybe I could use
quad chips instead for my modules and go with something like 40 pins.

Is size/density an issue? I.e., more liberal contact spacing might improve your ability to route the signals without undue coupling.

Are your modules going to use printed wiring? I.e., does the "plug"
that mates to these sockets mount *onto* the card? Can you use fingers, instead (more costly to manufacture; why pay a PCB house to plate
them when you can purchase a "plug/socket" that is already plated)

It is not a data bus — purely analog — so I'm not looking for some kind of data bus design.

How durable do you want the finished assembly to be? I.e., are you
just trying to use it to mock-up designs? Or, are you intending to
*deploy* a system thusly assembled? How fussy can you be in assembling
(and disassembling) such a configuration -- how durable do the
connectors need to be?

Something like this (simply by way of example):

<https://www.digikey.com/en/products/detail/sullins-connector-solutions/EBC06MMMD/1922782>

wouldn't need to be part of a "backplane PCB" but could just be fastened to
a support member spaced appropriately from its neighbor(s)

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What are you building?

I built small analog computer recently:

http://gem.librehacker.com/gemlog/starlog/20250514-0.gmi http://gem.librehacker.com/gemlog/starlog/20250523-0.gmi http://gem.librehacker.com/gemlog/starlog/20250523-1.gmi

I was considering maybe doing a version two of this project. I'd like to
have little card modules (integrator modules, etc) that connected to the backplane via sockets of some kind. And also the cables going to the
patch panel(s) would connect to sockets. These would be tied together
via wiring on the backplane. I was hoping I could keep the backplane as
generic and cheap as possible, so I didn't have to figure out in advance exactly how I wanted to wire up the module<->patch panel connections,
and also so I could change said wiring in the future without having to
reprint the backplane.

I don't like using offshore PCB printing, even though it is cheaper. I
like OSHPark, but they are more expensive and have a three board minimum
print for any single design.

--
Christopher Howard

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On 2025-05-28 13:58, Christopher Howard wrote:

What are you building?

I built small analog computer recently:

http://gem.librehacker.com/gemlog/starlog/20250514-0.gmi http://gem.librehacker.com/gemlog/starlog/20250523-0.gmi http://gem.librehacker.com/gemlog/starlog/20250523-1.gmi

I was considering maybe doing a version two of this project. I'd like to
have little card modules (integrator modules, etc) that connected to the backplane via sockets of some kind. And also the cables going to the
patch panel(s) would connect to sockets. These would be tied together
via wiring on the backplane. I was hoping I could keep the backplane as generic and cheap as possible, so I didn't have to figure out in advance exactly how I wanted to wire up the module<->patch panel connections,
and also so I could change said wiring in the future without having to reprint the backplane.

I don't like using offshore PCB printing, even though it is cheaper. I
like OSHPark, but they are more expensive and have a three board minimum print for any single design.

Well, since you're using a patch panel anyway, why not just run the
power and ground on the backplane?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

--- SoupGate-Win32 v1.05
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Well, since you're using a patch panel anyway, why not just run the
power and ground on the backplane?

Perhaps I misunderstand your question. But if I connect the patch panel
signal wires directly to the component modules, like I did with my
current (already built) analog computer, then the wires end up taking a
lot of space around the component modules, and you can't simply
remove/replace modules without wiring stuff back up to the card.

The patch panel can be variously organized according to how you want
various component I/Os grouped. I was wanting to be able, for example,
to plug in a new patch panel without having to do anything to the cards,
though maybe I would have to do some modification to the back plane
wiring if the new patch panel expected more signals.

--
Christopher Howard

--- SoupGate-Win32 v1.05
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How are you planning on supporting these cards? What sort of masses
involved? Any connections to the opposite end of the card (that would
add to the stress on such a "socket")?

I was imagining that they would be fairly small cards, something like
5mm wide by 6 or 7 mm long, with lightweight components only on the card
— small ICs, resistors, and such like. Certainly much smaller and
lighter than something like a graphics card. Nothing on the opposite end
of the card.

My original thought was to have the cables to the patch panel(s) hook
directly into a socket as well, but maybe I could have a shorter cable
going from that to some kind of plug in port on the chassis.

Are you certain that (analog!) signal integrity won't be an issue with
this approach? The frequencies and signal levels involved (as you
likely will be severely constrained as to HOW a signal can be routed
from "socket A" to "socket F")

I'm working always at low frequencies, like 100 Hz or less. The
simulations usually display on an oscilloscope at around 1 second per
scan, or slower.

Are your modules going to use printed wiring? I.e., does the "plug"
that mates to these sockets mount *onto* the card? Can you use
fingers, instead (more costly to manufacture; why pay a PCB house to
plate them when you can purchase a "plug/socket" that is already
plated)

The plug would mount onto the card, unless I was using just contacts
that slide in. I am open minded to ideas.

I don't really want to use printed wiring, preferring to experiment/design/build as I go. But I'm not really sure a practical way
to do that outside of a breadboard. Maybe I can come up with some kind
of generic printed board that gives me some flexibility on how I solder
on ICs and wires.

How durable do you want the finished assembly to be? I.e., are you
just trying to use it to mock-up designs? Or, are you intending to
*deploy* a system thusly assembled? How fussy can you be in assembling
(and disassembling) such a configuration -- how durable do the
connectors need to be?

It would just sit on my desk. I'd need to be able to slide in/out or (dis)connect the module cards without anything breaking. After assembly,
I would mostly be interacting with just the patch panel, not the cards,
but I'd want to be able to take cards out to tweak them, or replace
them.

wouldn't need to be part of a "backplane PCB" but could just be
fastened to a support member spaced appropriately from its neighbor(s)

Ah, okay, so I could just screw that onto some support structure, then
wire wrap to those long posts. Assuming the posts are strong enough to
endure wire wrapping.

--
Christopher Howard

--- SoupGate-Win32 v1.05
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On 5/28/2025 2:55 PM, Christopher Howard wrote:

How are you planning on supporting these cards? What sort of masses
involved? Any connections to the opposite end of the card (that would
add to the stress on such a "socket")?

I was imagining that they would be fairly small cards, something like
5mm wide by 6 or 7 mm long, with lightweight components only on the card
— small ICs, resistors, and such like. Certainly much smaller and
lighter than something like a graphics card. Nothing on the opposite end
of the card.

Yikes. And you want them removable/repluggable? The connectors may prove to be bulkier than the boards! (the example I provided likely is!).

If you were NOT expecting to disassemble/reassemble, I might have just suggested DIP parts carriers plugged into WW DIP sockets -- which could
even exploit a 2-dimensional layout instead of "all in a row".

But, even using machined-pin carriers, these will be pretty fragile
for reuse.

My original thought was to have the cables to the patch panel(s) hook directly into a socket as well, but maybe I could have a shorter cable
going from that to some kind of plug in port on the chassis.

Are you certain that (analog!) signal integrity won't be an issue with
this approach? The frequencies and signal levels involved (as you
likely will be severely constrained as to HOW a signal can be routed
from "socket A" to "socket F")

I'm working always at low frequencies, like 100 Hz or less. The
simulations usually display on an oscilloscope at around 1 second per
scan, or slower.

OK. It wasn't clear from your initial post.

Are your modules going to use printed wiring? I.e., does the "plug"
that mates to these sockets mount *onto* the card? Can you use
fingers, instead (more costly to manufacture; why pay a PCB house to
plate them when you can purchase a "plug/socket" that is already
plated)

The plug would mount onto the card, unless I was using just contacts
that slide in. I am open minded to ideas.

I don't really want to use printed wiring, preferring to experiment/design/build as I go. But I'm not really sure a practical way
to do that outside of a breadboard. Maybe I can come up with some kind
of generic printed board that gives me some flexibility on how I solder
on ICs and wires.

If you are using perfboard, you will be constrained as to the locations
and placements of devices (based on the "holes"). If you can stick
with DIP packages, this could be OK. SMT might be a stretch to fabricate
like this (esp if you didn't want to be forever "patching" it)

How durable do you want the finished assembly to be? I.e., are you
just trying to use it to mock-up designs? Or, are you intending to
*deploy* a system thusly assembled? How fussy can you be in assembling
(and disassembling) such a configuration -- how durable do the
connectors need to be?

It would just sit on my desk. I'd need to be able to slide in/out or (dis)connect the module cards without anything breaking. After assembly,
I would mostly be interacting with just the patch panel, not the cards,
but I'd want to be able to take cards out to tweak them, or replace
them.

How about splaying the backplane out "like a circuit board" instead of
like a set of card slots? Imagine "postage stamp" modules arragned
side by side, row after row (i.e., in a small grid) such that you
could see and access all of the components WHILE it is assembled.
Flip it over to do point to point wiring, as required.

There, you might be able to come up with a different mechanincal
design for the modules -- one that mimics a DIP (with a row
of pins on each "end") and plugs into a set of contacts
similarly arranged.

This does the "major, intermodule" wiring on the backplane and still
leaves you the freedom to tweak any interconnections WITHIN a
module AND OBSERVE THE ENTIRE CIRCUIT WHILE POWERED.

Size is just a tradeoff between how delicate you want the modules
to be and the number thereof.

wouldn't need to be part of a "backplane PCB" but could just be
fastened to a support member spaced appropriately from its neighbor(s)

Ah, okay, so I could just screw that onto some support structure, then
wire wrap to those long posts. Assuming the posts are strong enough to
endure wire wrapping.

The real downside risk would be if *a* post snapped while the others
were intact. You'd have to remove the entire connector just to
restore that post's functionality.

[If the entire "site" was unused when the break happened, you just
replace the whole connector.]

--- SoupGate-Win32 v1.05
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On Wed, 28 May 2025 14:10:00 -0800, Christopher Howard <christopher@librehacker.com> wrote:

Well, since you're using a patch panel anyway, why not just run the
power and ground on the backplane?

Perhaps I misunderstand your question. But if I connect the patch panel >signal wires directly to the component modules, like I did with my
current (already built) analog computer, then the wires end up taking a
lot of space around the component modules, and you can't simply >remove/replace modules without wiring stuff back up to the card.

The patch panel can be variously organized according to how you want
various component I/Os grouped. I was wanting to be able, for example,
to plug in a new patch panel without having to do anything to the cards, >though maybe I would have to do some modification to the back plane
wiring if the new patch panel expected more signals.

Design a motherboard with some female DIN connectors in a row and
ground/power bussing and the rest of the pins poking out. Buy a bunch
of cheap boards. The motherboard is the patch panel.

Pluging analog boards have a mating male DIN, which will lock in to
the motherboard nicely.

Some people make standard jumper wires with crimped terminations that
slide over wrap-post type pins without actually wrapping. Use those to
patch the backplane connections. They are reusable.

--- SoupGate-Win32 v1.05
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Don Y <blockedofcourse@foo.invalid> writes:

If you are using perfboard, you will be constrained as to the locations
and placements of devices (based on the "holes"). If you can stick
with DIP packages, this could be OK. SMT might be a stretch to fabricate like this (esp if you didn't want to be forever "patching" it)

The first analog computer used just DIP and through-hole components. I'm open-minded at this point on DIP vs SMT — but I don't really know how to prototype with SMT components and the stuff I've read
scratching/drilling divides into copper boards doesn't sound very
practical. But maybe I should try something new. Copper-clad perfboard
sounds like it might be a practical, inexpensive approach.

How about splaying the backplane out "like a circuit board" instead of
like a set of card slots? Imagine "postage stamp" modules arragned
side by side, row after row (i.e., in a small grid) such that you
could see and access all of the components WHILE it is assembled.
Flip it over to do point to point wiring, as required.

There, you might be able to come up with a different mechanincal
design for the modules -- one that mimics a DIP (with a row
of pins on each "end") and plugs into a set of contacts
similarly arranged.

This does the "major, intermodule" wiring on the backplane and still
leaves you the freedom to tweak any interconnections WITHIN a
module AND OBSERVE THE ENTIRE CIRCUIT WHILE POWERED.

Size is just a tradeoff between how delicate you want the modules
to be and the number thereof.

This basic idea sounds appealing.

The real downside risk would be if *a* post snapped while the others
were intact. You'd have to remove the entire connector just to
restore that post's functionality.

[If the entire "site" was unused when the break happened, you just
replace the whole connector.]

So, on the "postage stamp" board, how do you think I should do the interconnections? Wire wrap between posts? Or just do a solder bridge
over to the next perfboard hole and connect a wire to that?

--
Christopher Howard

--- SoupGate-Win32 v1.05
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On Thu, 29 May 2025 09:07:52 -0800, Christopher Howard <christopher@librehacker.com> wrote:

Don Y <blockedofcourse@foo.invalid> writes:

If you are using perfboard, you will be constrained as to the locations
and placements of devices (based on the "holes"). If you can stick
with DIP packages, this could be OK. SMT might be a stretch to fabricate
like this (esp if you didn't want to be forever "patching" it)

The first analog computer used just DIP and through-hole components. I'm >open-minded at this point on DIP vs SMT — but I don't really know how to >prototype with SMT components and the stuff I've read
scratching/drilling divides into copper boards doesn't sound very
practical.

It's fast, fun, and works great.

https://www.dropbox.com/scl/fi/t8q4luubibzlr6oqyrlim/Z338_PCB.JPG?rlkey=o23l9jq8y81n7799po4quof18&raw=1

https://www.dropbox.com/scl/fi/6pfssxz68ay8t64yh6xag/Z356_SN2.JPG?rlkey=o89t5tjsxh31264zbsirjin47&raw=1

https://www.dropbox.com/scl/fi/ydvcds95zvzjq56bzeimr/Z412_Proto.JPG?rlkey=hyejukxbbnk3573engf0if4zt&raw=1

But maybe I should try something new. Copper-clad perfboard
sounds like it might be a practical, inexpensive approach.

Plain copperclad is better. The back side can be your ground plane.

--- SoupGate-Win32 v1.05
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On 5/29/2025 10:07 AM, Christopher Howard wrote:

Don Y <blockedofcourse@foo.invalid> writes:

If you are using perfboard, you will be constrained as to the locations
and placements of devices (based on the "holes"). If you can stick
with DIP packages, this could be OK. SMT might be a stretch to fabricate
like this (esp if you didn't want to be forever "patching" it)

The first analog computer used just DIP and through-hole components. I'm open-minded at this point on DIP vs SMT — but I don't really know how to prototype with SMT components and the stuff I've read
scratching/drilling divides into copper boards doesn't sound very
practical. But maybe I should try something new. Copper-clad perfboard
sounds like it might be a practical, inexpensive approach.

You're "building" at two different levels.

You are creating these "modules". Then, interconnecting them (via your "backplane")

Can I step back and ask what roles each of these activities will play?

E.g., when I was in high school, I built a football (american) game
out of "analog computers" and "logic boxes" (we didn't have "real"
computers at that point). It was ferried to school on a 4x8 sheet
of plywood, largely because the analog computers and logic boxes were physically large -- like briefcases that (open) exposed their functions
for use.

The individual modules (sum/gain/integrate/etc.) were hidden "inside"
the OPENED briefcases. They were interconnected using discrete wires
with tapered pins that could be wedged into holes in the briefcases.
(so, they were somewhat permanent but could be dislodged with deliberate effort)

I'm likening your project to the modules being the sum/gain/integrate/etc functions implemented in your "modules" with the "tapered pin interconnects" being your "backplane". Is this approximately true? I.e., once you've designed the individual modules, they'll be static (likely replicated)
with the real changes happening in the backplane wiring?

If so, how persistent (permanent) do you need this to be? I'm sure
a 4'x8' board is impractical (I had to build it in the basement) but
could some other form of interconnect be MORE appealing?

I'm thinking back to the days when Radio Shack sold kits of components
mounted on a piece of cardboard in a "board game sized" box with
"springs" used to connect wires to each endpoint of each component.
(bend spring to open a gap in the coils, insert wire, release -- spring
holds wire captive).

How much of your goal is flexibility in reuse vs. size vs. cosmetics?

The real downside risk would be if *a* post snapped while the others
were intact. You'd have to remove the entire connector just to
restore that post's functionality.

[If the entire "site" was unused when the break happened, you just
replace the whole connector.]

So, on the "postage stamp" board, how do you think I should do the interconnections? Wire wrap between posts? Or just do a solder bridge
over to the next perfboard hole and connect a wire to that?

Dead bug or some variation thereof. If you use leaded components,
you have the length of the leads to determine how far apart
components can be.

If (as I've assumed), you want the modules to be durable and reusable,
you could pot them when completed; all you need is access to the
pins of the *module*, not their internals.

(With DIP carriers, you could glue a cover onto the base to protect the components and interconnects hidden inside)

--- SoupGate-Win32 v1.05
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On 5/29/2025 1:18 PM, Don Y wrote:

The individual modules (sum/gain/integrate/etc.) were hidden "inside"
the OPENED briefcases.

I.e., when you opened the briefcase, none of the components were visible.
There were schematic symbols drawn on a plastic (wood?) surface. The schematic connections to each symbol terminated in these "conductive holes" that accepted the tapered pins.

In this way, the electronics were protected from being disturbed/broken
by careless students. And, the illustrations on that wooden surface
let the student see what they were attempting with their interconnections.

They were interconnected using discrete wires
with tapered pins that could be wedged into holes in the briefcases.
(so, they were somewhat permanent but could be dislodged with deliberate effort)

--- SoupGate-Win32 v1.05
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Christopher Howard <christopher@librehacker.com> writes:

- on the raised islands, is that just another layer of copper clad
laminate? Is there some special material I'm seeing underneath the
blue break-out boards? What tool do you use to cut out chunks of the
laminate?

Also, what glue do you use when you need to glue on pads or components?

--
Christopher Howard

--- SoupGate-Win32 v1.05
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The first analog computer used just DIP and through-hole components. I'm >>open-minded at this point on DIP vs SMT — but I don't really know how to >>prototype with SMT components and the stuff I've read
scratching/drilling divides into copper boards doesn't sound very >>practical.

It's fast, fun, and works great.

The pictures look beautiful. Can you answer a few questions?:

- Is that "double sided copper clad laminate PCB circuit board" like
available all over Amazon?

- What method/tool do you use to scratch/cut-out the divides in between
the islands?

- on the raised islands, is that just another layer of copper clad
laminate? Is there some special material I'm seeing underneath the
blue break-out boards? What tool do you use to cut out chunks of the
laminate?

--
Christopher Howard

--- SoupGate-Win32 v1.05
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I'm likening your project to the modules being the sum/gain/integrate/etc functions implemented in your "modules" with the "tapered pin interconnects" being your "backplane". Is this approximately true? I.e., once you've designed the individual modules, they'll be static (likely replicated)
with the real changes happening in the backplane wiring?

I think the one part you are not understanding is the purpose of the
patch panel. So, it would be like so:

- Fixed analog component modules — integrators, multipliers, and such
like — connect to the back plane. These modules are normally not
changed out except for repair, testing, and expansion.

- Cables from the patch panel(s) connect to the backplane. Wiring on the
backplane connects these cables to the component modules. This wiring
is not normally changed unless adding new patch panels or some
fundamental redesign of a patch panel port.

- The patch panels(s) have a bunch banana jacks allowing me to quickly
interconnect the inputs and outputs of the various analog components.
These connections are frequently changed — every time I set up a new
simulation.

This is how it works with my current analog computer I built, except
that there is no backplane. Rather, the wires from the patch panel
cables connect directly to terminal blocks on the analog component
modules.

--
Christopher Howard

--- SoupGate-Win32 v1.05
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On Fri, 30 May 2025 08:57:27 -0800, Christopher Howard <christopher@librehacker.com> wrote:

The first analog computer used just DIP and through-hole components. I'm >>>open-minded at this point on DIP vs SMT — but I don't really know how to >>>prototype with SMT components and the stuff I've read
scratching/drilling divides into copper boards doesn't sound very >>>practical.

It's fast, fun, and works great.

The pictures look beautiful. Can you answer a few questions?:

- Is that "double sided copper clad laminate PCB circuit board" like
available all over Amazon?

Yes, but I have mine gold plated. It solders great and doesn't tarnish
in a few weeks like bare copper does. One of our PCB suppliers make
it for me for about $100 a square foot.

- What method/tool do you use to scratch/cut-out the divides in between
the islands?

A Dremel with a carbide dental burr. I draw lines with a Sharpie first
and clean up with Soft Scrub. The cutting takes some practice to get
good at. One can make controlled-impedance microstrip lines and do
picosecond stuff.

These people Dremel their pumpkins.

https://www.dropbox.com/scl/fo/ybvag1tipbns3farz13zj/h?rlkey=itrnz8fvpcnfpgnzso7bk4txz&dl=0

- on the raised islands, is that just another layer of copper clad
laminate? Is there some special material I'm seeing underneath the
blue break-out boards? What tool do you use to cut out chunks of the
laminate?

"Manhattan style" is gluing little pedestals to the base board. We
have a metal shear to slice up the FR4. A serious hole punch would
make round ones.

I attach the purchased surface-mount adapters with double-stick foam
tape.

FR4 strips used as bus bars or transmission lines are epoxied down.

--- SoupGate-Win32 v1.05
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On Fri, 30 May 2025 09:06:22 -0800, Christopher Howard <christopher@librehacker.com> wrote:

Christopher Howard <christopher@librehacker.com> writes:

- on the raised islands, is that just another layer of copper clad
laminate? Is there some special material I'm seeing underneath the
blue break-out boards? What tool do you use to cut out chunks of the
laminate?

Also, what glue do you use when you need to glue on pads or components?

Double-stick foam tape or 5-minute epoxy.

--- SoupGate-Win32 v1.05
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On 5/30/2025 10:16 AM, Christopher Howard wrote:

I'm likening your project to the modules being the sum/gain/integrate/etc
functions implemented in your "modules" with the "tapered pin interconnects" >> being your "backplane". Is this approximately true? I.e., once you've
designed the individual modules, they'll be static (likely replicated)
with the real changes happening in the backplane wiring?

I think the one part you are not understanding is the purpose of the
patch panel. So, it would be like so:

- Fixed analog component modules — integrators, multipliers, and such
like — connect to the back plane. These modules are normally not
changed out except for repair, testing, and expansion.

They "plug in" to the backplane.

- Cables from the patch panel(s) connect to the backplane. Wiring on the
backplane connects these cables to the component modules. This wiring
is not normally changed unless adding new patch panels or some
fundamental redesign of a patch panel port.

So, all these are doing is acting as convenience functions; giving
you access to the backplane without having to directly wire ON the
backplane.

- The patch panels(s) have a bunch banana jacks allowing me to quickly
interconnect the inputs and outputs of the various analog components.
These connections are frequently changed — every time I set up a new
simulation.

OK. I was assuming the backplane was acting as your patch panel,
hence needing reasonably robust means of reusing connection points.

This is how it works with my current analog computer I built, except
that there is no backplane. Rather, the wires from the patch panel
cables connect directly to terminal blocks on the analog component
modules.

So, the backplane is just a packaging convenience?

--- SoupGate-Win32 v1.05
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So, the backplane is just a packaging convenience?

Correct. A backplane is not absolutely necessary, since I built one with
out a backplane. But it is bothersome to have the wires from the patch
panel hooked directly to the modules, as it is quite messy and makes it
more difficult to work on the modules or to replace/modify the patch
panels(s).

--
Christopher Howard

--- SoupGate-Win32 v1.05
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On 5/30/2025 2:21 PM, Christopher Howard wrote:

So, the backplane is just a packaging convenience?

Correct. A backplane is not absolutely necessary, since I built one with
out a backplane. But it is bothersome to have the wires from the patch
panel hooked directly to the modules, as it is quite messy and makes it
more difficult to work on the modules or to replace/modify the patch panels(s).

Yes. Your approach makes perfect sense -- esp if you intend to
reconfigure the "assembly".

In the example I provided, it was a "finished piece" -- despite
being too physically large to STORE as built.

[Your talk of modules had me thinking you would be building
different devices that you would leave configured]

--- SoupGate-Win32 v1.05
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I like this idea of building the modules on top of FR-4 boards. However,
this leaves me unclear on how I should interface the modules to the
backplane. The "postage stamp" idea was appealing, but I am not sure how
I would attach the pins. I know I don't want to be trying to drill very
precise holes, or to be scratching out 20 little islands on the copper.
Any further thoughts on this?

--
Christopher Howard

--- SoupGate-Win32 v1.05
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On Fri, 30 May 2025 14:34:35 -0800, Christopher Howard <christopher@librehacker.com> wrote:

I like this idea of building the modules on top of FR-4 boards. However,
this leaves me unclear on how I should interface the modules to the >backplane. The "postage stamp" idea was appealing, but I am not sure how
I would attach the pins. I know I don't want to be trying to drill very >precise holes, or to be scratching out 20 little islands on the copper.
Any further thoughts on this?

I don't exactly know what you want to do, but here is one posibility:

Design two double-side PC boards and order some from one of those
cheap houses.

Use mating connectors, D-subs or DINs. The one on an analog board is a right-angle and the motherboard/patch panel gets straight ones with
wire-wrap tails. Those are available.

The motherboard can do some power bussing. A motherboard could be
short, 3 or 4 connectors, and designed so they can be bolted together
into longer strings.

The baby boards will plug into the mobo and the connectors will hold
them up. Include some common parts like power supply filters and LEDs
and such. Maybe some opamp footprints.

Nice plated holes and ground planes and ways to prototype.

Maybe make an extender board too.

That's almost a product.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)