This circuit makes use of a low impedance microphone. The relay is according to the supply voltage which can be between 9 and 15 V. The operational gain is approximately 100.
This high input impedance amplifier stage was found in a 1963 documentation. The transistor...
The circuit shown has the advantage over the reductions with resistors to have a much higher...
This circuit amplifies signals from 10 MHz to 500 MHz with a gain of 10 dB. We found it in...