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 MW radio for the medium wave range (OM) uses three transistors and outputs to a speaker. L2...
This 60’s commercial flash was found in the march 1961 Radio Electronics Magazine. The circuit uses...
This circuit for RF signals was found in the March 1987 issue of Radio Electronics magazine. The...