This 4-channel mixer amplifier was found in an American publication from 1947. The circuit uses counterphase output tubes and a transformer power source.
For experiments with ionization chambers and Geiger valves this circuit generates high voltage from...
Found in American documentation from 1969, this circuit switches signals with a FET of the time....
This circuit is from an April 1991 Radio Electronics magazine. The circuit uses power MOSFETs and...