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.
This circuit was found in an American documentation from the 70s, but it can be implemented with a...
This integrated contains a Class B circuit originally developed to provide 6 W in a car radio...
This differential amplifier, found in a 1964 Electronic Design, has a gain of 30. The setting can be...