The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from April 1990 we have a flame detector.
A 3-terminal voltage regulator can be used as an efficient temperature regulator for a current...
Connected to the output of an audio amplifier or radio this circuit indicates the level of the...
This two-transistor circuit was found in a 1966 US documentation. The power transistors are of the...