This 3-valve receiver was found in a publication by Edelman from 1924. The circuit has two supply voltages, B being 60 to 90 V.
Found in a Popular Electronics from the 90s, this circuit uses components that are still current....
This circuit uses an operational that is not currently common. We found it in an old American...
This circuit was obtained from an Electronics World of 1968. The transistor may be general purpose and...