This receiver is from a 1924 Gernsback publication. The receiver has good efficiency when powered by the indicated voltages. Listening is through a high-impedance phone.
Found in Radio Electronics from the 90s, this circuit converts signals from the 9.5 to 9.8 MHz...
This circuit was found in a 2000 documentation. The circuit generates a sequence of notes...
This small transmitter with 2 transistors can reach several hundred meters using a 30 to 70 cm...