This ingenious circuit was found in a 1990s Popular Electronics. The oscillator is a 555 and the keyer uses an optocoupler in the configuration shown.
This circuit was found in a 1977 Signetics manual. The 556 consists of a 555 double and the...
One of the first transistor amplifiers with transformerless output but using a 45-ohm speaker. This...
With this simple converter found in a 1997 documentation, it is possible to tune VHF stations to a...