This is my variation on the venerable Atari Punk Console circuit, which I call the Atari “Punch” Console. The output of the original APC is ‘punched up’ with 3 sub-octave square waves which add more harmonics into the mix, resulting in a fatter tone. The sub-octaves are generated with a CD4024 binary counter, and are then summed together. They are mixed into the output by way of R6, which varies between the pure ‘punk’ output of the 556, and an equal balance of the 556 and the suboctaves.
As drawn above, the circuit has a 2Vp-p output (+/-1 volt), suitable for connecting to a line-in, assuming the circuit is run off of 9V. However, replacing R11 with a larger value (3k3, 4k7, etc) will produce greater voltage swing at the output.
Get the schematic and board files (Eagle v6) at GitHub!
Parts list (Mouser Project Page):
- 1x Atari Punch Console PCB (get it from OSHPark!)
- 2x 2×3.5mm terminal blocks (Mouser)
- 1x 10uF/16V aluminum electrolytic capacitor (Mouser)
- 2x 100nF ceramic capacitors (Mouser)
- 2x 10nF ceramic capacitorcs (Mouser)
- 1x 1K/0.25W resistor (Mouser)
- 2x 2.2k/0.25W resistors (Mouser)
- 4x 10k/0.25W resistors (Mouser)
- 1x 10k linear potentiometer (Bourns PTV09A style – Mouser)
- 2x 100k linear potentiometers (Bourns PTV09A style – Mouser)
- 1x CD4024BE binary ripple counter (Mouser)
- 1x NE556N dual timer (Mouser)
I’ve actually had this circuit kicking around for a while but I never wrote it up or designed a proper PCB for it. I took advantage of some free time recently to do just that.
If you build it, drop me a note in the comments or on Twitter and let me know how it comes out!