Use an ATTINY85 chip to convert or multiply or divide clock signals

A tiny hack using a cheap IC and some potentiometers to convert clocks between synthesizers.

Synthesizers sometimes can be controlled by a “clock” which simply a steadfast rule to how fast the clock should go or how many volts it should be. Some devices send/recieve a clock at 1 pulse / beat, while others send/receive a clock at 2 pulses / beat. Some devices expect a clock peak-to-peak voltage of 5 volts, while other devices exepct a clock peak-to-peak voltage of 1 volt.

Of course there is a cottage industry of modular systems for eurorack that exist to fill in the gap and add some clever additions. I recently found myself needing a clock-to-clock converter/divider/multipler but don’t have a eurorack, nor the money to spend on one.

So this week’s tiny hack is a a tiny clock-to-clock converter. Its a small device (bigger than all the other tiny hacks) that take any clock signal at any level (0 - 5v) and convert it to another clock signal (up to x4 or /4) at any level (0 - 5v).

What does this tiny hack do?

This tiny hack lets you use the “clock” out/in signal between musical instruments, regardless of how that particular’s instrument particular clock signal works (its level, or its frequency). Here is an example using a drum machine (the Bastl Drum) synchronizing a SH-01A.

Why do this tiny hack?

My true motivation is to sync my instruments together with the clock signal. However I found that several of my instrumetns have very different clocking requirements:

  • Pocket operator: 1-5 v, 16 pulse / measure
  • SH-01A (in only): 5 v, 8 pulse / measure
  • Bastl Drum: 4.5 v, 16 pulse / measure

No combination of any of these instruments would provide consistent clocking! So I resolved to make a really simple solution that was also configurable depending on which pari of instruments I would use.

How do I do this tiny hack?

This hack is more involved than any of the others. It requires a microcontroller, for one - the Attiny85. You can also use an Arduino if you have - actually you will need an Arduino to program the Attiny85 (or a USB programmer).

Materials needed:

  • Attiny85 or Arduino for doing the clocking logic
  • 10k potentiometer for setting voltages and changing clocking mode
  • OLED screen for visualizing tempo and settings
  • 5.1v diode is used to prevent harm to connected instruments in case of malfunction (specifically 5.1v!)
  • Breadboard is nice to initiate the build for this hack

Uh oh something bad happened!

Oh no! I’m happy to help - just DM me on Twitter (@yakczar) or email me.

 / music electronics hack 

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