This circuit makes use of a stroboscopic tube, a component that no longer exists today. The circuit is from the 70's and can be adapted to use mains voltage.
This circuit triggers the LED when the monitored battery voltage drops below 9 V for 12 V...
This power control for the AC power line uses a Triac and an Unijunction Transistor. The control...
The purpose of this circuit is to eliminate RF picked up by a turntable. The circuit is from a...