Hohner Automatic Rhythm Player goes MIDI

YouTube via MusicMiK

"Started to fix my Hohner Automatic Rhythm Player i got a while ago. All the PCB retainers fouled away to an undefined strange soft chewing-gum like matter, so they need replacement in the near future. Currently, i added some provisoric stuff to keep the boards in place and make the box usable.

During the repair (that this video should handle), i decided to add MIDI to it, so this video now is the story about developing and making a small MIDI retrofit for this nice machine.

It currently works in a very primitive way - after investing just about one day of work into it. The firmware will be enhanced to add the following features:

- Using the configuration button to enable a learn mode to set the MIDI channel and assign instruments to the MIDI notes (while multiple notes can trigger the same instrument) and set other things. Input devices are MIDI note events and the green button i added at the rear, output devices are the instruments to give some feedback by playing sounds.
- Implement the blocking of MIDI triggering when the internal sequencer runs, even if the hardware doesn't care about concurrent triggering, nothing can be damaged due to the diode matrix and my way of triggering the instruments being friendly to each other.
- Implement MIDI out for the internal diode matrix sequencer, including MIDI clock and start/stop, which should be possible with the current hardware. MIDI note assignment also takes place in the configuration then. Not too useful, just "because we can" :) The output might also be available as software MIDI thru, using filtering.
- Maybe add some means of accentuation, which this machine is currently missing, but i have some port pins available which should make this possible.

Another useful modification would be separate outputs for all instruments, i'm thinking about this but will do this a bit later. First, the unit needs some restoration after this quick idea of the MIDI input. With this, it really makes some serious sense in the studio as i no longer need to use the preset rhythms."