Solid state relay (CB8518E)

This circuit was found in a 90s Popular Electronics. Both the coupler and the MOSFET can be of any type.

100 kHz Colpitts (CB25681E)
This crystal-controlled oscillator was found in the January 1994 issue of Electronics Now. Other...
Tunnel Diode Receiver (CB10602E)
This circuit is from a 1964 publication. The circuit takes advantage of the component's resistance...
Converter Stage of a Transistor Radio (CB937E)
This is a converter stage found in old transistor superheterodyne radios. The circuit is for...