Found in American documentation from the 90's, this circuit oscillates up to 150 MHz. The transistor supports an equivalent and the diode is general-purpose.
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...