We found this circuit in a 1966 documentation. The circuit is intended for a door opening system by the headlight of a car. The sensor is a photo-FET, an uncommon component today.
This small audio amplifier is based on the LM390 with a minimum of external components. We found it...
This circuit was obtained from Elektor magazine and published in the Encyclopedia of Electronic Circuits...
We found this configuration in National Semiconductor's Linear applications Handbook. The circuit...