Multipurpose temperature control (CB21368E)

This circuit was found in a 1967 RCA SCR manual. It uses period components that can be replaced with modern equivalents.

Amplifier for multimeter (CB23868E)
This circuit had its assembly described in a Radio Electronics from March 1963. The circuit uses 2...
555 in Cascade with Automatic Retrigger (CB1265E)
We found this configuration in a documentation for radio amateurs from 1974. The circuit can be...
Microphone preamp (CB22149E)
We found this circuit in an English documentation from 1989. The integrated circuit used is not...