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.
Texas Instruments UCC21225A is available from Mouser Electronics. It is an isolated gate driver...
We found this circuit with very high input resistance in an old documentation. The circuit is still...
This configuration was found in a 1976 publication. The outputs of the logic circuits are applied to...