This circuit was found in a 1964 Electronic Design. The transistor may be a current equivalent of general use. The frequency ranges from 100 to 150 Hz.
This circuit is intended to reinforce old car radios, having been found in 1997. At that time,...
The Sample and Hold circuit shown in the figure was found in a 1994 Linear Applications Handbook by...
Found in a 1980s documentation, this circuit detects when the voltage drops below 11 V. Other...