It was a Crybaby Wah pedal, a classic effects pedal typically used for a guitar. Since it was somewhat damaged, [Scissorfeind] got to work creating a control voltage (CV) and volume circuit for ...

The wah-wah pedal makes a guitar sound as though it's singing "wah, wah, wah." The effect was a staple of 1960s psychedelic rock: Jimi Hendrix bent reality with it in classics like "Voodoo Child ...