This very simple circuit uses a phototransistor and a very sensitive relay (reed type) being used over short distances with a lens system. The circuit is from a 1967 Japanese publication.
Using an integrated circuit from the time, this circuit was found in Radio Electronics from the...
This power supply can provide 10 A currents. Its regulation is made by 7812 integrated circuit. The...
The circuit shown in the figure can be used to connect a loudspeaker to an amplifier only after...