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 conventional slow-moving circuit uses incandescent light bulbs, but can be changed to use...
This TTL dice is from an old publication from 1978, but it can still be assembled, as the...
The purpose of this circuit is to control magnetic door locks activated by the power grid. The...