Capacitance multipliers are how wah-wah pedals work. The classic Vox / Dunlop/ Cry Baby wah-wah pedal used by Hendrix, Gilmour, Clapton, Harrison, and so many

Capacitance multipliers are how wah-wah pedals work. The classic Vox / Dunlop/ Cry Baby wah-wah pedal used by Hendrix, Gilmour, Clapton, Harrison, and so many others, is built from a resonant LC filter. How do you change the resonant frequency of an LC filter with a pedal mechanism? The pedal turns a pot, and that controls a capacitance multiplier circuit. Simple and elegant.