This 4-tube amplifier with 6W of output was found in an American manual from 1947. The sound quality is excellent.
Using an optocoupler this circuit turns on the light in a bedroom for a set amount of time when...
This basic voltage comparator circuit has a reference voltage given by a zener diode. The input...
Found in a Hands On Electronics of the 80s, this circuit makes use of a gas sensor of the time....