How do you synchronise your modular synth with MIDI equipment? MIDI provides the MIDI clock message, but you need something to convert this to a format an analog modular synth can understand. Most MIDI-to-CV convertors will do the job, but that can be expensive. Here’s a cheap way to do it.
The Druid MIDICLK chip converts MIDI clock signals into 0-5V analog pulses. It provides two separate analog clock outputs, which can be set at various division ratios of the MIDI clock, which allows crazy polyrhythmic mayhem if you’ve got two independent sequencers. It also produces short 0-5V pulses for the MIDI Start, Stop, and Continue messages, as well as providing a ‘Running’ output which is high whilst the MIDI clock is running. These signals can be used to control your analog circuits.
Below is a example circuit which shows the various features of the code. It uses potentiometers for all the options, but for specific applications, these could be presets or particular voltages. For example, it’s unlikely you’d really need VR3 for control over the Start, Stop, and Continue pulse length. You’d pick a couple of resistor values and set up a divider that gives a reasonable pulse length for your circuit, or tie the pin to ground with 10K if you’re not using those outputs.
Great, but what could I actually use that for?
The circuit above will replace the typical LFO clock in most analog sequencer designs and allow you to synchronise your analog sequencer with your MIDI equipment.
It can also be used to synchronise the sequencers in monosynths like the SH101 or the Sequential Pro-One. Using an external clock with these synths frees up the LFO when the sequencer is running, which is a big step forward!
It’s a simple circuit, and it’s only designed to do one thing.
If you’d like to build one, or like to know how I built mine, perhaps you’d like to look at:
- MIDICLK PIC 16F688 ASM code
- Assembled HEX code from above file
- MIDICLK datasheet (includes example circuit diagram, chip pinout, and details of division ratios)
Currently,there are no plans to offer the MIDICLK chip in the shop, so I’m afraid you’ll have to program your own chip, or find a friend to program one for you. If you’d like to see programmed chips in the shop, send us an email, and if there’s enough interest, we’ll do it!