This circuit for monitoring telegraphy transmissions was found in a 1975 CQ magazine. Transistors may be modern equivalents.
This circuit can handle 25 A unde a 32 V voltage using a hight power old transistor. This...
This solid-state relay (SSR) or shield was found in a 1995 Electronics Now. The transistor can be...
Found in 80's Electronic Engineering, this circuit can tune the frequency to be rejected. The power...