Univox Uni-Comp Model CO-105 schematic and board pics  [schematic]

Discussion regarding early stompbox technology: 1960-1975 Please keep discussion focused and contribute what info you have...
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Bside2234
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Post by Bside2234 »

Just picked this up and couldn't find any info about it here so I thought I'd add it.
IMG_3230sm.jpg
IMG_3229sm.jpg
IMG_3227sm.jpg
IMG_3228sm.jpg
Uni-Compcomponents.jpg
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uni-compschematic.png

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reddesert
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Post by reddesert »

Great pictures and work.

There is a 33 uf cap on the board that is not in the schematic. This should go from the collector of the transistor (+ end of the cap) to the emitter / ground.

There are several schematics floating around for the Uni-Comp and they're all a little different.
1. Bside2234's schematic above.
2. one at http://www.davidmorrin.com/home/trouble ... x-uni-comp. Here he has a 3.3K and 1K resistor in parallel from +9V to the vactrol. This doesn't make sense and I suspect that one of them is supposed to be a 10 uf capacitor.
3. one for the seemingly identical Melos Comp at http://files.effectsdatabase.com/docs/f ... matics.jpg. This has a 2.2K resistor and 10uf cap from +9V to the vactrol.

Finally, there are unverified vero layouts at http://tagboardeffects.blogspot.com/201 ... -comp.html, for the David Morrin and Melos schematics (but the comp pot is backwards). And there's a DIYSB thread at https://www.diystompboxes.com/smfforum/ ... msg1111474. The tagboardeffects gang and Mark Hammer on DIYSB appear to agree that the rectifying diode D1 should be a germanium or Schottky. Not sure about the clipping diodes D2 and D3.

I built one with D1 = BAT46; D2, D3 = silicon, using a LED+LDR in place of the vactrol, after cleaning up the various errors, and it does work.

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Manfred
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Post by Manfred »

I have created a PCB layout clone for all vintage fan.
Layout:
Univox Uni CompLayout.JPG
Ready to print files, print as original size:
Univox Uni Comp PCB Solder.pdf
(9.64 KiB) Downloaded 154 times
Univox Uni Comp PCB Components.pdf
(11.68 KiB) Downloaded 148 times
SprintLayout6 file:
UnivoxSPL6.zip
(19.08 KiB) Downloaded 150 times

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