This highly sensitive light sensor was found in a 1970 General Electric documentation. The circuit can use the 2N2646 for the UJT and the phototransistor can be of any type.
This receiver for listening to the TR-23 phone was manufactured in Japan in the 1960s. The circuit is...
This circuit is from a 1992 documentation, but the components used can still be easily assembled. The...
This circuit was found in the SGS manual of linear integrated circuits of 1982. The circuit...