ENVGEN 8C VCADSR Envelope Generator

(7 customer reviews)


121 in stock (can be backordered)

SKU: ENVGEN8 Category:
1 - 9 £5.00
10 - 99 £4.00
100+ £3.00


This chip is a comprehensive upgrade of the previous generation of Electric Druid voltage controlled envelope generator chips, the VCADSR 7B and LOOPENV 1B. The VCADSR had both GATE and TRIGGER inputs, and the LOOPENV featured a MODE CV that allows selection of normal ADSR, Gated looping, or full LFO-style Looping modes. This chip combines the features of both onto a single chip, and removes the need for a crystal and reconstruction filter. It also improves the output sample rate to 31.25KHz, improves the envelope table resolution, and uses a multiplying DAC for the output, which allows full analog Level CV control without any loss of resolution or calculation errors.

The ENVGEN8C chip keeps the other features of the originals, like full voltage control over all parameters (Attack, Decay, Sustain, and Release)l, and the TIME CV which shortens the overall time of the whole envelope. The TIME CV makes an excellent modulation input for either envelope modulation or LFO frequency modulation. It also adds a PUNCH input which holds the maximum level for a few milliseconds before starting the Decay stage. This is very useful for adding extra punch to short percussive envelopes.

Download Electric Druid EnvGen8C datasheetDruidDatasheetPDF

The datasheet includes example circuit diagrams, example waveforms, and the chip pinout diagram.

If you’d like to program your own chip for personal use, code and further details are available over on the original article about the new Druid chips.



7 reviews for ENVGEN 8C VCADSR Envelope Generator

  1. ehk506 (verified owner)

    Absolutely love this chip, ridiculously easy to use and beautify versatile. 10/10 would ENVGEN8 again

  2. David

    absolutely very great chip!!
    but there might be a bug, i’m not shure.
    what happens: pin3 is grounded for adsr-mode. but when i power up the chip, its always in gated looping mode…
    when i apply first 5v to pin3, then go back to 0v, then it will go into adsr mode. why is that?
    is there a way around it, or am i doing something wrong?

    cheers to your very nice chips! very good work!!

    • Tom Wiltshire

      Yes, I think this is “normal”. It happens because currently the chip only responds to *changes* on the pin, so until something is altered, it doesn’t reset the variables.
      I’ve got one other minor tweak to release for this code, so there’ll be a ENVGEN8B along soon, and I’ll make sure to check this out and fix it while I’m doing it.

      Thanks for the pointer – the more people there are spotting stuff like this, the better the code can get.

  3. Gunnar

    I also have this PIN3 “problem”
    When I power up my system with Normal ADSR mode (grounded) selected I have no signal coming out. I first have to change modes then everything works fine.
    When I power up with Gated Looping or LFO/Looping mode selected everything works fine from the beginning .

    Is an update to ENVGEN8B already available?

    • Tom Wiltshire

      Yes, it is. ENVGEN8C fixes this problem and another minor bug where the chip wouldn’t power up correctly if the Gate was high (which is an over-voltage condition – not good!).
      We’ll have the new chips in stock and the updated code online shortly.

  4. Gunnar (verified owner)

    i changed the old ENVGEN8 in my module to the new ENVGEN8C and everything works fine now. Thank you.
    What to do with the old chip? I don’t have the hardware (and knowledge) to flash it. But it would be nice to use it in another project.
    Is there a workaround for the PIN3 problem?
    Can we get 5v to pin 3 on module startup which then discharges (capacitor). Or a transistor switch?

  5. Filip Woźniak (verified owner)

    Hi, can I use 100k pots instead of 10k?

    • Tom Wiltshire

      Yes, the pots are wired as voltage dividers, so the chip isn’t too fussy about the value. I’ve tried various things from 100K-10K without problems.

  6. Goncalo

    Hi, first thx for the great work, im a big fan! I have a question about disableing cv level, why this big cap 100uf to ground? Thanks in advance

    • Tom Wiltshire

      The Level CV input supplies the reference voltage to the on-chip DAC, so any noise on that CV input will go straight through to the output. Since +5V supplies are often quite noisy, the 330R/100uF is acting as a filter to help remove any power supply noise. To be honest, a 100nF ceramic cap in parallel with the 100uF to reduce high frequency noise would be a good idea too, as a “best practice” solution.
      However, if you’ve got a nice quiet low impedance voltage source that you can use instead, you can drop the filter and connect it directly to the Level CV.

      Note also that it only needs to be between the supply voltages of the EnvGen chip itself (so typically from 0-5V, although you can also run the chip on 3.3V or less). In the datasheet circuit, I have Level CV tied to 5V, so we get a 5V envelope, which is then reduced with a voltage divider before going to the VCA. An alternative (and equivalent) approach would be to tie the Level CV to a 2V source, and then the envelope would already be correctly scaled when it left the chip and the 15K/10K divider would not be necessary.

  7. Jerker Lindborg (verified owner)

    I just got my 10 ENVGENs and are about to get me a separate voltage regulator to step down to 5V.
    What I wonder is how much “over voltage” the ENVGEN can handle as the regulator has a specification of ±4%.

    Cheers from Sweden!

    • Tom Wiltshire

      The ENVGEN8 chip will run with a voltage anywhere from 1.8V to 5.5V, so if your regulator was +/-10%, you’d still be ok.

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