This power supply uses a Raystor which is a 1964 LDR lamp coupler. The circuit was found in an Electronic Design and the transistor can be replaced with the current equivalent.
This circuit is from 1968 documentation. We can assemble it with more modern components such as a...
Found in a 90s Silicon Chip documentation this circuit is intended to protect a speaker system in...
The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from...