This circuit was presented in a January 1990 Radio Electronics magazine article as part of a home theater sound effects system. It consists of a 3 kHz high-pass filter.
This low drift or offset circuit is from an 80's documentation. The configuration can be made with...
This circuit has a logarithmic response as a function of the light falling on the sensor. The...
Found in 80's Electronic Engineering, this circuit can tune the frequency to be rejected. The power...