Found in a 90s Elektor, this circuit makes use of general-purpose transistors, except T4 that can be replaced by an 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...