This trimmer or reaper amplifier cuts the signal peaks at a voltage determined by the zener diodes. The gain is given by R1 and R1 and the power supply must be symmetrical from 5 to 15 V.
This 1 A circuit was found in a Philips documentation from 1966. The transistor is of the time,...
This circuit generates an audio tone whose frequency depends on R1 and C1. See in the math section...
This circuit, in addition to providing an output that corresponds to the absolute value of the...