Found in documentation from 1924, this receiver has several sets of coils. Power is supplied by several batteries and listening on high-impedance headphones.
This is a conventional double T oscillator, where the frequency is determined by the double T...
This simple audio signal tracer or follower can be made with a BC548 instead of the original...
I found this circuit in a 1992 Electronics Experimenter Handbook. The circuit can be easily...