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 an EEE this circuit uses FETs of the time and a bipolar one. Current equivalent...
This capacitive switch or approximation relay was found in a 1980s US publication. Power should...
Although it is a common configuration today, this circuit was taken from an old publication. The...