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 circuit with SCR is from a Radio Electronics magazine from September 1965. It is a commercial...
This circuit was found in the July 1986 issue of Radio Electronics magazine. The circuit has a...
This circuit was found in a QST from the 1990s. The circuit expands the scale of a 10V instrument to...