This circuit was found in 1967 General Electric documentation. The transistors of the time can be replaced by modern equivalents.
The transistors in this 1978 circuit can be BC548 and 1N4148 diodes. The electrolytic capacitors can be...
This shield circuit is suggested by Texas Instruments and can employ almost any optical coupler...
This circuit was found in an American documentation from the 90s. It consists of a variable with a...