Found in the April 1978 issue of Radio Electronics magazine, this circuit is intended to be powered by a symmetrical 15 V source. The signals are low intensity.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...