This circuit was found in a 1966’s American publication. What it does is to receive a pulse and keep it for intervals of up to 1 minute at the output.
This circuit, which can be used as a shield, was found in American documentation from the 1970s....
This circuit for low frequency data transmission was found in the May 1977 issue of Radio...
This circuit activates a relay that has a lamp as a load. The circuit is from a Radio Electronics from...