We found this circuit in an American documentation from 1975. The list of transistors that can be used is attached to the diagram. Modern types can be experienced.
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...