amplifier - How the low pass filter works in this circuit? - Electrical Engineering Stack Exchange
audio filter circuit : Audio Circuits :: Next.gr
Analyzing the Moog Filter - Technical Articles
PWM, Low Pass Filter, Transistor, & P Channel MOSFET - General Electronics - Arduino Forum
ElectronicsNotes on Twitter: "It is very easy to make a simple high pass filter out of a single transistor circuit stage. #highpassfilter #circuitdesign https://t.co/2hHxXL91OZ https://t.co/L58JP0UolS" / Twitter
Can I build active filters with BJT instead of opamps? - Quora