Twin T Filter Overview

[@rickjljr11]

Isn't the second circuit, the band amplifying filter, just an oscillator? How do you stop it from doing that? The Twin T has a 180 deg phase shift, the op-amp inverts the signal, another 180 deg and it has plenty of gain. 2 pi around the loop and gain >1.

[@gadgetsideload]

In a more complete implementation of that circuit as a filter there's another feedback path added. In this video I used it as a Wah filter effect and then modified it to force oscillations (first step toward drum synth) kzbin.info/www/bejne/qWe4ZaeElL-leJI