Found in a 1968 Texas Instruments documentation this circuit uses an SCR from that time. Modern equivalent types can be used for a higher power version.
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...