This circuit from General Electric was found in a 1967 documentation. The SCR is of the time, as are the transistors, but equivalents can be used.
The S-meter is signal strength meter, coupled to telecommunications receivers to indicate the...
This power supply can be implemented with a TIP32 providing an adjustable output at the 2k2...
This circuit was obtained from a 1967 magazine. The magazine no longer exists, but the circuit can still...