Monday, 13 March 2017

Univox Uni-Comp

Not much info on this one, but basically it was a compressor made by Univox in the 70's as part of their "foot" series. Seems to be loved by many and was recently requested. In addition to the schematic posted in the request section I found another schematic posted over at FSB, so I made 2 different layouts.

One thing to note is that the original didn't use an LED & LDR, but used a Vactrol labeled MCD527. I'm not quite sure what color LED and LDR range you should use. I would start with try a red LED and socket the LDR and try different ones to get a good range. If you were to try a vactrol maybe a NSL32 or VTL5C3 which have bee used on many different optical compressors.

Don't forget if you're using an LED & LDR to cover them in shrink wrap to block out any light and increase their efficiency and effect.

Layout 1: Based on the Schematic in the Request Section


Layout 2: Based on the Trace ad FSB of a Uni-Comp Model CO-105



16 comments:

  1. Looking at the minimal datasheet I could find here: http://www.datasheetarchive.com/dlmain/3a432e73794c72004043cbb83187adec39ebb7/M/MCD527

    and here:
    http://www.grandpas-shack.com/parts/datasheets/CdS_Photo_Couplers(Moririca).pdf

    You could say the LDR is 1k-2M closest LDR would be the GL5537-1 (not GL5537-2) which is 20k/30k - 2M. Not really close but closest I could find. It pairs good with a amber/green LED as the spectrumpeak is at 540nm.

    Vactrol-wise you could consider the VTL5C3, also not a perfect match, but covers the spectrum.

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    1. Great. I couldn't find the data sheet for some reason. I'll add the info to the build notes.

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  2. It's possible to get the Avalanche run schematic?

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  4. The germanium diodes should be D1, D2 and D3 and the LED D4?

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    1. They're all in the right place as far as I can tell. Its just labeled different.

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    2. Yea. I didn't realize the numbering was off. I'll fix that in a few.

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  5. I think so too, it's just the labels. I've got some VTL5C3's so I'm gonna give it a go at the weekend.

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  6. Would a MPSA18 or BC550 work in this? I don't have any of the above transistors, so before I go buy some I'd thought I'd ask first!

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  7. The MD234 diodes aren't germanium ones! There are silicon (http://www.datasheetarchive.com/dlmain/356b7aff6be6417173704f4e3a807d3ad96c94/M/MD234).

    Thank you all!

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    1. According to both people that traced their Univox Uni-Comp pedals said the diodes were germanium. The diodes could have gone from germanium to silicon at some point in production, but I don't know. Could socket the diodes and try silicon and germanium to see what's best. I tend to trust the people that traced the pedal till we get confirmation from a build here.

      Nice job on finding the data sheet, btw.

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  10. I apologize if this is an incredibly beginner question, but when the layout shows a wire going to "Comp 2 & 3", does that mean you have two wires going from one hole to 2 & 3 on the comp pot, or can you run one wire from that hole to 2 on the comp pot, and then a connector from 2 to 3? Thanks!

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  11. A single wire from the board and join the wire across lugs 2 and 3.

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