Found in a 1924 Gernsback publication this circuit uses 4 batteries for power and loop antenna. Listening is over a high-impedance type earphone or loudspeaker common at the time.
The current drained by this circuit, from a 1976 documentation, is 3 mA and the cut-off frequency is...
This circuit for 12 V relays was found in the July 1992 Radio Electronics magazine. The circuit is set...
This circuit generates high pulses from a sinusoidal input, using SCRs for this purpose. The...