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.
Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It...
The integrated circuit used in this project is uncommon today, as we found the configuration in a...
This variable high frequency oscillator circuit was found in an old English documentation. The...