I thought I’d try changing the pitch of a guitar string by pulling it with a solenoid – thus “tension guitar.” I thought I’d be able to get multiple pitches by turning the puller on and off very quickly (PWM) but that didn’t work well, so I was stuck with just two pitches. That was boring, so I added a little finger that frets the string. With the combination of the two, it can play four pitches. Over and over and over, thanks to the automatic strummer. Like this. There’s also video of the various moving parts here.

thing a day 22: tension guitar from ranjit on Vimeo.

Details of the strummer, finger, and puller.