The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from April 1990 we have a flame detector.
With this name, we find a photorelay in a publication from 1966. The transistor is made of...
This 6-transistor Japanese radio from the 1960s used germanium transistors and had an output power...
The waveform generated by this circuit produces a sound similar to that of a bird. The circuit is based...