strum plate

[Dimitree]

hi everyone

I'd like to have some suggestion for how to make a strum plate like the one used on the Suzuki Omnichord:

 

 

 

essentially it is a set of 12 touch sensors placed along a strip.

I thought about the SoftPot resistive strip, but I could only detect position on the strip and I couldn't trigger more than 1 signal at once.

I read about capacitive sensing but seems like there are many disadvantages.

what could be a solution?

and what do you think the Omnichord strip is made of?

 

[Duggle]

IR photo interrupter techniques work well for this kind of application.

I once prototyped a photo harp that worked really well (long ago).

It was velocity sensing based on the timing of breaking closely placed pairs of IR beam paths.

 

If you're good with DIYing some circuitry, it can be achieved with: (an IR diode, IR photodiode, an opamp, 2x resistors, and a DIN input) x 12, in this case.  Also +7V, -5V supply for the op amps.

If you're good with firmware, the MIDIbox KB, or even NG could be adapted for velocity sensing based on timing between breaks in beam pairs.

Otherwise MIDIO128 would work off the shelf.

 

Let me know if you're interested in the circuit for the the IR beam sensor.