This electronic Morse key was found in a Popular Electronics from the 90's. The components are common, but there is a mechanical part that requires assembly skills.
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...