Tuesday, 31 August 2021

DOD Envelope Filter 440 Reissue

 Per request. This is supposed to a great envelope filter with both up and down sweeps.

Schematic is avaiable HERE.


 




9 comments:

  1. Thank you!
    That's surprising : isn't the original supposed to work with an unobtainium vactrol?
    By using OTAs, the reissue makes it closer to the FX25...?

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    Replies
    1. Yes, the "classic" 440 had an optocoupler and a completely different circuit.
      This one one the other hand has more in common with FX25 just as you said. Some parts of the circuit is almost identical but there is also lots of extra stuff happening.

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  2. gave this one a try - no luck. I get a very quiet fuzzy signal

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    Replies
    1. I'll take a look at the schematic again...

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  3. Did you get chance to check out the schem again mate? I built up the guyatone one, really interested in this too

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  4. Hey mate. No never got around to check the schematic, sorry about that. Will try to find some time the nexrt coming days.

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  5. Hey, got it working. There are two corrections to be made:
    -10k misplaced between Vref and grnd: move 10k from C14 to N14
    -move 22k from Q7 to R7
    Cheers!

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    Replies
    1. Thats awesome!
      Layout is tagged and updated.

      Delete
  6. As I know, FX25 uses LM13600 and 440 uses led/ldr combo. Is it different on the reissue?

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