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 80's circuit has been winning. It is a 1 000 gain sample and hold circuit and an offset...
The purpose of this 1-transistor amplifier is to allow the use of a milliammeter in an application...
We found this circuit in an old General Electric documentation. In fact, PUTs are not common...