Minimal Drum Machines

This is a video demo of Eric Archer’s Minimal Drum Machines – a DIY preset beatmaker that can communicate wirelessly with other minimal drum machines, sync and create more complex rhythms.

Details below.

via EA78751:

I’m testing the definition of “drum machine” with these fun little prototypes. They have only two chips, (TL06x opamp and CD4089). No microcontroller. One knob (tempo). One button (reset). Sixteen rhythm presets on a DIP switch. Light reactive circuits to bend the sound.

Even though the machines can play alone, they’d rather play in a group. Thats because each machine has an infrared transmitter and receiver. This lets them form a wireless network to play at the same tempo. The IR link is limited to about 12? and does not work under bright incandescent light. (the video was shot with compact fluorescent)

At the end of the video I show how interrupting the IR link affects the sound. In theory, many of these machines could be networked.

Both machines in the video share the same sequencer design. It is based on the CD4089 binary rate multiplier. Their sounds are different though. The unit in the foreground uses a pair of bridged-T oscillators to make clave / rimshot / bongo sounds. The unit in the back generates filtered noise bursts with a classic “swing VCA” mechanism.

Once finalized the designs are intended for use in a fun educational workshop setting.

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