This circuit was found in an Experimenters Handbook of the 1990s. The purpose of this circuit is to keep constant the audio signal level of a system, increasing the lower signals.
We found this touch control on a Popular Electronics from 1970. The circuit makes use of an...
This very low frequency circuit was found in a 1964 Electronic Design. Transistors may be modern...
This circuit, from the 1990 Motorola Dataar Databook, can be implemented with other comparators. The...