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.
In the figure we have a Texas Instruments circuit for TTL interfacing using discrete transistors. The two...
This circuit was found in Radio Electronics magazine from June 1963. The range is small and the...
The project presented in a 2009 documentation is intended for radio amateurs operating in the...