This circuit was found in a 1924 Gernsback publication. The variable capacitors are dual. Listening is through a high-impedance phone.
Using an LDR as a sensor, this circuit is from the Radio Electronics magazine of December 1984. The...
A frequency range determined by the network of resistors and capacitors with negative feedback and input...
The energy that powers this radio's amplifier circuit is obtained from the signal itself. The coil...