DIY – Atari Punk Console – Stepped Tone Generator – APC MKII

Voici ma version évoluée de l’APC, transformée en module de percussion, FX. L’assemblage est réalisé dans un boitier Hammond, type pédale d’effet de guitare.


Pour la sérigraphie, j’ai choisi d’utiliser un autocollant plastifié. Après design sur Illustrator, j’ai eu recours à la société pour la fabrication. La commande minimum étant de dix stickers, il m’en reste quelques uns à vendre, si vous êtes intéressé -> MP. 😉


– Entrée CV Trig/Gate
– DC in 9V
– Sortie Audio ligne
– OSC APC, contrôles Pitch et PW/Divider
– LFO, contrôles Rate et Amount
– EG, contrôles Decay et Sweep
– Hipass Switch
– Mod Inv Switch

Les circuits LFO, EG et VCA sont inspirés du WP20 de Music From Outer Space. Le filtre Hipass est inspiré des cymbales, Hihat des TR808.

APC schematic

Implantation des composants  sur plaque à pastilles :

APC pcb

Petite subtilité pour le câblage. J’ai remarqué lors de la conception du circuit sur plaque d’expérimentation, que l’étage Hipass est très sensible au rayonnement provenant des câbles du potard Rate du LFO (particulièrement lorsque qu’il oscille à vitesse audio).
J’ai donc blindé tout le câblage du switch Hipass, du potard Rate et bien sûr de la sortie audio. Pour cela j’ai utilisé la technique de Ray Wilson MFOS.


Petite démo en situation (switch hipass activé) :

12 Réponses to “DIY – Atari Punk Console – Stepped Tone Generator – APC MKII”

  1. Great machine, you can post how can you wire panel?
    and refer point to connect… bless ya

    • Thank you for your comment!
      I don’t have any other wiring schematic, but if you look carrefully, I’m sure you’ll find how to do it properly.
      It’s not a hard project. 😉
      Try it on bread board first!

  2. You are a genius man! Thanks for sharing! APC MK II rules! 😉
    Keep up the good work and check out for experimental electronic music!

  3. Amazing mod to the classic APC circuit!

  4. hello man!
    i have some questions
    for the power part i see 5 100nf in parallel. can i use one 500nf?
    your build takes an input signal and make changes to it?
    i’m asking that cause i can’t understand what the input does. does this build work without an input signal?
    and one more. can i build it with 555? cause i can’t find the 556 here.

    • Hi!
      The 100nf are ICs decoupling caps and
      they should be as close as possible to the ICs.
      This design is a percussion generator. The input takes a pulse or gate (coming from other analog synth, sequencers…) in order to trigger the envellope generator.
      You can add a simple momentary push button to trigger the box manually. (Connect it between GND and R22/C16 junction).
      It shouldn’t be a problem to use 555. Look at the datasheet to match the pins. 😉

  5. This looks fantastic! Do you have any completed units that you would sell?

  6. Hi,

    Really cool APC 😀

    i were trying to build it, but i dont get it to work properly yet.
    i found a difference between the schematic and the pcb layout @ the decay pot between r24 and D2, its not in between on the pcb, but i gues its not really a problem?

    What kind of CV input does it need for triggering?
    i build it along with a diy Baby 8 Sequencer with CV output, But it doesnt seem to trigger the APC. might need some buffer? or does it need + and – Voltage?
    hope you can help me 🙂

    Thanks in advance,

    Greetings from Holland,


    • Hi! Thank you for your interest!

      You’re really right about the decay pot and the R24, there’s an inversion in the schematic and layout. But this is not a problem because the pot is wired as a variable resistor in serie with R24.

      The trigger input should react to a traditional Gate or Trig CV, like a positive 5V pulse of at least 10ms. It should work with the baby 8 sequencer. But I know this sequencer is really minimal without output buffer, so maybe the voltage drop is enough to not trig the circuit. By the way it would surprised me because this input is quite sensitive. I can trig the circuit only by touching the tip and sleeve of a jack plugged in. 😉

      Hope you will manage to get it right!
      Happy building!

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