This circuit was found in a Popular Electronics from the 90s. The counter circuit is not common today. The circuit can be programmed for hourly intervals, according to the values of R4 and C2.
The purpose of this circuit is to amplify the signal of a medium or high impedance microphone,...
Taking advantage of the two stable states of a tunnel diode it is possible to build a switching circuit...
We found this circuit in a 90s Electronic Design. The components admit current equivalents. The circuit...