1. antf4rm says:

    the trim pots on this bom have an incorrect mouser part number

    \1 50k Linear Single-turn Trim Pot R31 531-PTC10V-10K
    1 100k Linear Single-turn Trim Pot R8 531-PTC10V-50K

    These are too large. close but no cigar.

  2. Patrick Kelly says:


    Sorry about having the wrong part number on there, must have been a mistake. According to the datasheets, it looks like these will get you done. I’ll update the Bill of Materials to show this difference.

    50k Linear Single-turn Trim Pot R31 – 652-3306F-1-503
    100k Linear Single-turn Trim Pot R8 – 652-3306F-1-104


  3. antf4rm says:


    Why not stick with the sealed pihers just the right size?

  4. crt says:

    Would love this but I have a dot com system. Is it possible to build for 15v?

  5. Patrick Kelly says:


    We have not done any testing with +/- 15V on the DLY module. That being said, though, our ECHO can use 15v, and I believe this one may be able to as well. The onboard voltage regulator can definitely handle it, and the TL072 ICs should be fine with it, but it is untested, and we can’t guarantee it will work.

    -Patrick at Synthrotek

  6. Christophe Teissere says:

    I don’t find the CI PT 2399 on mouser.
    Could you Help me?
    Thanks and wonderful products !!!

  7. Alex Tinsley says:

    In the visual bill of materials you have the LM78l05 shown, in the parts list it shows LM78L05. Perhaps change the visual bill of materials from lower case “l” to upper case “L” in the part number.

  8. Patrick Kelly says:

    Hey Alex, Good catch! I’ll make sure that gets changed.


  9. chub says:

    Hi Patrick,

    Is there a schematic available for the DLY module? I’d like to compare it with the Echo and also buy extra parts for little mods I’d like to make to put the DLY into my mostly MOTM system. Nice sounding module, by the way! Thanks for the videos.

  10. Steve Harmon says:

    Hey Chub,

    Due to different licensing agreements, we are not able to make all of our schematics available to the public.
    Here is a demonstration of the differences between the DLY and Echo:

    If you have specific mods in mind we would be happy to offer any help we can!


  11. chub says:

    @Steve Harmon
    Thanks Zach! I’ve built the module and the only issue I found is that I can’t get the full delay range with the +- 15 volt MOTM supply. I did a quick calculation and it seems that changing R24 (300K) to a 120K will provide the required -5 volts to the input of the CV circuit. I’ll swap R24 out and test tomorrow, then send you the results.

    The only other mod I could want may be a little more low pass filtering of the delayed signal. Given how the module will get used, however, this can be accomplished elsewhere in the patch. Also, I’d hate to limit the output just to mellow it.


  12. chub says:

    Well now, I got that exactly wrong! It seems I should calculate for current through the 300K resistor at -12 volts and divide -15 volts by that current, giving me a resistor value for R24 of 375K.

    Time for a rest.

  13. chub says:

    DLY module working as it should now! R24 was changed to 390K and the delay time CV and control pot sweep the delay time through the entire range. I adjusted the trim pot for a little bit of glitchy fun at the upper end of the range, too.

    Great little module, and fairly easy to adapt to other formats! Thanks Synthrotek!


  14. Zetsu says:

    I’m curious about the optional R13. What is that part doing? If I omit it, should I complete that connection with a resistor leg?

  15. Synthrotek says:

    Hi Zetsu, go ahead and populate it if you have a 1M resistor. Don’t use a resistor leg.

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