Found in American documentation from the 1980s, this circuit can be designed with equivalent components. The microphone can be of the piezoelectric type.
The voltage gain of the circuit shown in the figure is 10 times. This gain is given by the ratio...
This circuit, from an old Argentine publication, uses a slightly different symbology than we are...
In this circuit we have two oscillators, one controlling the other, using the 4 NAND gates of the...