Atari Punk Console

The Atari Punk Console (commonly shortened to APC) is a popular circuit that utilizes two 555 timer ICs or a single 556 dual timer IC. The circuit is a simple DIY noisemaker circuit that is relatively inexpensive and easy to build, easily adaptable and is configurable in many ways. It has been built into a wide variety of enclosures. Its flexibility has led to wide popularity. It is often suggested as a good circuit to build for beginners.

History
The original circuit, called a "Sound Synthesizer", was published in a Radio Shack booklet: "Engineer's Notebook: Integrated Circuit Applications" in 1980 and later called "Stepped Tone Generator" in "Engineer's Mini-Notebook – 555 Circuits" by its designer, Forrest Mims. It was named "Atari Punk Console" (APC) by Kaustic Machines because its "low-fi" sounds resemble classic Atari console games from the 1980s, with a square wave output similar to the Atari 2600. Kaustic Machines added a -4db line level output to the circuit which was originally designed to drive a small 8-ohm speaker.

How it works
Atari Punk console is an astable square wave oscillator driving a monostable oscillator that creates a single (square) pulse. There are two controls, one for the frequency of the oscillator and one to control the volume. The controls are usually potentiometers but the circuit can also be controlled by light, temperature, pressure etc. by replacing a potentiometer with a suitable sensor (e.g., photo resistor for light sensitivity). Most of the time there is also a power switch (often a toggle switch) and a volume knob.

Problems
With a pot turned down to minimum, because internally the 555 shorts pin 7 to ground during parts of the oscillation, there will be a short circuit across the battery. There's needs to be something to limit the current through the pots and pin 7. Add a series resistor to each of the pots, e.g. 330 Ohms at 9 Volts will limit the power to just under a 1/4 Watt, (the rating of most pots). This will affect the frequency of the oscillator so you may have to experiment with higher value resistors.

Kits and PCBs

 * eMiZ Instruments