This circuit is from the time when cars used contact breakers. This 80's version measures the dwell angle of the contact breaker for dwell adjustment using an era integrated circuit, the LM3917.
This detector is from the 1990 Motorola Dataar Databook, but can be adapted to work with more...
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
This is the traditional Hartley Oscillator configuration for high frequencies. For 1 MHz wind 80...