Interest in prefab smd utility circuits?

[mrand]

I was wondering if people would be interested in an assembled smd board covered in handy utility circuits. They could be arranged so that one could cut them apart to be integrated into your diy builds as needed. I was thinking stuff like:
-VCA
-expo current source with empty holes for your thru hole matched transistors and tempcos
-buffered multiple
-LFO

Basically just circuits I find myself building repetitively and/or things I'd like to integrate into my modules.

I'm more or less thinking out loud here. I certainly don't have the expertise to do orchestrate something like this quite yet, I don't even know how to do PCB layouts. So far I've done all my building on protoboard. That said, it doesn't seem too far off...

[m.o]

[elmegil]

V2164's have single chip VCA and to some extent expo conversion covered, look up some stuff by Dr Etch N Sketch (he posts mostly at Muff's I think). Not sure that those applications have a lot of advantage by getting into smd matched transistors etc....

[okelk]

in smt you could make use of cheap matched transistor pairs like the dmmt3906/dmmt3904.
Awesome part but a pain to hand solder (SOT-323).

could be used in exponential converters, as differential pair in an OTA based vca, transistor ladder filter or even a discrete vca.....

there are also relatively cheap (and not even too hard to get) smt tempcos.
I don't know if it would be possible to get thermal contact between two neighboring smt parts...maybe glue a small copper plate on both the transistor pair and the temco?...

[mrand]

Thanks for your replies, people, all good suggestions.

I feel like the thermal contact thing would be easy to solve, how about encasing the area in epoxy?

Maybe I should have mentioned that another motive of mine is miniaturization. I'm trying to build a compact modular.

[okelk]

I thought about a blob of thermal conductive glue too, but I guess one would have to try, because electrically non conductive often just means barely conductive...

[mrand]

I have developed a small utility PCB which includes an LFO, a mixer, and a s/h. They are break-apart sections on a 5x5cm board.
If anybody wants 10 of them, I would be happy to provide you with the link to where the design is hosted at dirtypcbs. I think I get $1 of store credit every time someone orders it. Obviously this is not a commercial venture, so I'd also be happy to provide the gerbers if anybody wants to take it to their own fab house. I simply want to share with the community who has helped me get this far

[mrand]

Hello people,

If anyone is interested I'm preparing a layout for a 3046 heater type expo current source PCB.

The design is based on the system100 vco. Adaptation from ua726 to 3046 is based on frequency central's implementation as well as the doepfer vco.

The intent is to make it easier to breadboard/prototype future VCO designs.

See attachment for schematic and 3d drawing of my PCB layout.
This is a work in progress! I need to fill out all the values still.

Comments welcome!

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heated3046expo_source.jpg
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[mrand]

try again with the schemo upload

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heated3046expo_source_schemo.pdf
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[blue hell]

Would this be a uA726 replacement?

(I have a defect VCO using that chip and suspect the chip to be gone, although I did not actually check that)

[mrand]

[blue hell]

Ah ok, thanks for the feedback :-)

[LFLab]

I would be interested in some kind of breakout board for BCM847 and BCM857 double transistors, I can't manually solder them anymore, so having boards with them on it would be beneficial.
I did a layout once with these, and two SMT tempco resistors, to LM394 footprint (and two holes to connect to the tempco).