Hardware Update

Once I got the robotic accordion up and running, I discovered a couple of issues. The bellows were more leaky than I realized. I took out the bellows and added a plastic liner. This dramatically improved the volume of sound produced by the instrument.


After a period of extended use, the relay that controls the direction of the motor failed. I suspect this occurred because the abrupt motor direction changes that I was subjecting the relay to. Any motor produces a back current while it is turning (acting like a generator). I believe that while the relay was reversing the polarity of the motor back and forth, substantial electric arcs were probably occurring inside the relay (as the motor keeps turning for a fraction of a second while the current reverses). This probably damaged the relay contacts over time. Also, the relay was handling close to its maximum rated current of 5 amps (the motor probably draws more than 5 amps when it first starts turning).

I was lucky enough to find some 10 amp relays that have the same pinout as the 5 amp relays, so I replaced all the relays on the board. In addition, I modified the Arduino code to shut the power off to the motor for a fraction of a second while the motor direction is changed. Hopefully these changes will extend the life of the control circuit.

Following is the current Arduino code that is running on the instrument. It includes changes to make the motor direction control and limit sensing more robust.

[Deep|Remote] Listening Device Firmware 1.12