http://www.getlofi.com/?p=518

«The so called “Atari Punk Console” device is a great start for builders interested in working with components and circuitry to produce Bleepy-Bloopy-Gitchy goodness. Using a 556 dual timer IC and a handful of other components one can be built quickly. The basis for this noise maker was a schematic originally published by Forest Mims III, which now can be found around the web and posted above for easy reference. The APC can be built into any case of your desire, and in the case of The SquareWave Parade even a vintage Atari joystick. The circuit is not only easy to build, but it is also easy to modify. The 556 IC is very resilient and cheap so don’t be afraid connect various pins to each other in order to discover new sounds. Touch contacts can be added in conjunction or as a substitute for the potentiometers and different values of capacitors can be swapped in to change the tone color dramatically and provide greater expression».

Via: MAKE magazine