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.
August 2017 - STMicroelectronics' BlueCoin development environment is available at Mouser...
We found this circuit in the January 1978 issue of Radio Electronics magazine. The integrated...
Found in a 90s Electronic Design, this circuit generates harmonics from a sinusoidal input signal....