I like the Korg Volca series especially the Volca Bass. I also like the TT-303 (TB-303 clone). They sound fantastic and are a great addition to any synth jam session. If, however, you like to create EDM, the one element you need is a pumping bassline by feeding an audio signal through a compressor and apply side chaining. But that can take quite a bit of time in setting up and keeping it running smoothly (as you need a steady audio kick to feed the side chain). So, I thought of approaching things from a different angle; what about passing audio through VCAs and drive these VCAs by means of an Arduino and, in turn, a Digital to Analog converter driving the VCAs. This project, The Bouncer, does exactly that. The Arduino runs in sync with a MIDI clock and you have two dials (Bounce & Grit) two tweak the pattern of volume modulation. Please watch the youtube video below to get an idea. The effect is perhaps not immediately noticeable but it's certainly there. Towards the end (3:40) the Bounce/Grit settings are more extreme and the volume-modulation is clearly audible (like the bass is running in reverse).This project is based around the SSM2164 (quad VCA). Two VCAs process a mono signal each (like the Volca bass and TT-303). The remaining two VCAs process a single stereo signal; this could be the Volca FM for example. There is a fourth stereo channel, which is just a pass through into the mixer stage; this could be the drum section such as the Volca Sample.I put this project in a semi-translucent box and thought it would be cool to add two internal tri-colour LEDs in there for a nice visual (as the Arduino has plenty of I/O to play with).The Bouncer also has Gate & CV out to drive a Eurorack. The Gate sends 5V trigger pulses at 4/4 and the CV is a duplicate of the control voltage driving the internal VCAs (visualised by the large LED next to the Bounce dial).Oh, and last but not least; with so many Volca boxes around, it would be good to have a few MIDI patch points - so, I added 3 x MIDI THRU. Enjoy!

Step 1:

Please see the schematics and components list here.

Step 2:

Please see the strip-board layout; here you can see connectivity to all the external items such as 3.5mm panel mount jacks and dials etc., components layout and where/what tracks to cut.