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.
This amplifier with a few watts of power was found in a Japanese technical documentation from the...
This circuit is from a 1977 National Semiconductor integrated circuits manual. The circuit admits...
This conventional power supply uses discrete components and can provide 12 V or 13.6 V output with...