Make: Electronic Music from Scratch

THE ACTIVE LOW-PASS FILTER

The active low-pass filter, no surprise, is exactly the same as the high-pass filter,

but with the position of the capacitor and the potentiometer switched (Figure

D

).

Here’s what it looks like on a breadboard (Figure

E

).

D

E

Chapter 8: Filters 171

THE ACTIVE BAND-PASS FILTER

A band-pass filter lets a “band of frequencies” pass through—you can pick how

wide or narrow the band is. For example, you could tune a band-pass filter

(Figure

F

)

to only allow a specific range of notes to pass through. A passive

band-pass filter is ...