This variable filter circuit was found in July 1975 Radio Electronics magazine. The circuit uses 3 general purpose op-amps like the 741 and must use a symmetrical source.
This old circuit from a documentation from the 70s disconnects a TV from a signal obtained on the...
This traditional complementary symmetry circuit provides 20 W of rms power at a load of 8 ohms...
Using a CA3130 and a power transistor, this circuit can deliver a current of up to 500 mA with the...