[sdiy] Optical sensor for keyboard pedal

[Ben Stuyts]

Hi all,

Many years ago I bought a CME GPP-3 piano pedal, which turned out to be a shoddy piece of garbage. It is a 3 pedal board (una-corda, sostenuto, damper) with USB, Midi and jack outputs and some programmability through a cpu. At first the switches for the left two pedals started behaving intermittently. Cleaned them a couple of times. Then the pot for the damper pedal became noisy. Oh, and the cpu locks up sometimes so you have to power-cycle the thing. And then it sometimes forgets how the jack outputs were configured (n/o or n/c). Reading some forums, I’m not the only one having these problems.

Here’s pics of the inside parts:

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Anyway, it’s been lying disassembled in a box for a few years. The mechanics and housing are actually quite nice, so why not put some new sensors and electronics in it?

I was thinking of using a couple of analog reflective optocouplers for it. This gives the option of having three analog pedals instead of just one. The range should be 8.3 to 11.3 mm if I put then in a similar position as the current switches are. Maybe using a Vishay TCRT5000, although an SMD one would be better with the sensors board lying right on top of the chassis.

Any thoughts if this would work in practice? Or maybe use a different sensor, like a hall-effect one?

And thinking about this, I also have a few old 49 and 61 key key-beds lying around with mostly bad contacts. Would be interesting to refit those with similar sensors. Price per sensor would become important then. Perhaps a small board with 1 octave worth of sensors plus a cpu for scanning. (What kind of sensors did the old Moog Piano Bar use?)
 
Ben