via this auctionvideo at auction and posted here
"The Techno-tari 2600 is an analog synthesizer that replicates a basic square wave synthesizer . It is a synth in its most basic form – but with a handful of controls, can provide anything from squelching Techno bass lines to glitchy arpeggios and droning bass notes. The Techno-tari 2600 provides thick analog synth sounds in a rehoused Atari 2600 console.
The core of the synth is from Forrest Mims' Stepped Tone Generator (STG), also known as an Atari Punk Console. I used this circuit to produce the square wave sound. The circuit has two PITCH knobs that control the frequency of each step in the waveform. So by having the VCO at its core, I added a circuit that emulated three more elements of an analog synth; a voltage controlled filter (VCF), a low frequency oscillator (LFO) and a voltage controlled amplifier (VCA).
The RATE knob is used to control the speed and can give anything to a throb to fast Techno-speed beating to a drone. Setting the control at maximum is like having the original sounds of the STG.The FILTER knob acts a tone control or VCF. Swept to its minimum, it acts like a high pass filter i.e. all high frequencies above a fixed point are passed through, cutting out the lower frequencies below the threshold. At its maximum, it acts like a low pass filter. This is subtractive synthesis at its most simplest – subtracting frequencies away from the whole (VCO) to provide a synthesised sound.
A FREQ switch allows a shift in octave of the oscilltor so you can go from chirpy, glitchy sounds to rumbling deep drones with one switch. Due to the change in frequency, the PITCH knobs act in a different relationship than before so experimenting here will give you a different low end result. Switch to the left is low frequency, to the right is high frequency.
Finally, I added a bit of a fuzz boost to beef up the filtered pulse wave, The stock sound was thin but by adding this VCA-esque stage, a thick squelchy sound is sent from the Techno-tari straight to the mixer/amplifier. The LEVEL control is the large knob and controls the final output of the signal.The Techno-tari 2600 operates off 9V DC using a standard 2.5mm negative tip power supply commonly used to power effects pedals. It has an on/off power switch and OUTPUT jack for plugging into headphones, mixer, amplifier or effects pedals."
