Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors support modern equivalents. The circuit can be used as a shield.
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...