Capacitive Relay (T1527E)

Found in Popular Electronics from August 1956 this sensitive two-tube relay is powered directly from the mains power supply.

Light Activated Switch (CB14457E)
This circuit is from 1968 documentation. We can assemble it with more modern components such as a...
Speaker protection (CB8193E)
Found in a 90s Silicon Chip documentation this circuit is intended to protect a speaker system in...
UV Sensor with UVTRON Tube (CB25942E)
The UVTRON tube is an ultraviolet radiation sensor. In this circuit from Radio Electronics from...