AC voltage control (CB8904E)

This circuit was found in a 90s Hands On Electronics. The semiconductor component is a Triac of the time.

Amplifier with modulator (CB9176E)
This circuit with a double-gate MOS transistor was found in a Popular Electronics from the 90's....
Light relay (CB23551E)
This photoelectric cell light relay was found in Radio Electronics magazine from April 1958. The...
Cassette Tape Retriever (CB10832E)
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...