We found this circuit in a magazine 73 for radio amateurs from the 80's. The circuit makes use of an epochal component which is programmed according to the table beside the diagram.
This circuit warns when the headlight bulb is on. We found it in a Popular Electronics from the...
The oscillator shown in the figure keeps its frequency constant in an active cycle adjustment...
This circuit was found in an Argentine publication from the 1970s. The circuit can be assembled with...