This interesting 1924 triode tube receiver was found in a documentation by Gernsback. Observe supply voltages. Coils are for tuned wavebands.
This circuit was found in old documentation and can be implemented with other operational...
Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors...
This circuit is from a publication from the 70s, but it can be assembled with any diac and a Triac...