This circuit was found in an English magazine from 1977. Signal inputs and outputs must be shielded, and the circuit can be powered by battery, since its consumption is low.
Used with telephones at the time, this circuit was found in Popular Electronics from the 90s. The...
This simple power supply is regulated by two zener diodes which, for a current of up to 200 mA,...
This circuit was found in the Italian magazine Radio Elettronica from September 1977. It is...