Found in a 1964 Electronic Design, this circuit makes use of period components. The components are from the time, and modern equivalents can be used.
With this circuit, a relay can be activated from an alternating signal with frequency up to a few...
With this circuit the visually impaired can easily locate important places inside the house, such...
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...