This circuit for RF measurements at 200 MHz was found in no documentation two years 80. At a sensitivity of 1V peak and the components used are still common in these days.
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...