Found in documentation from the 1980s, this circuit can have several adaptations to use modern transistors and LEDs instead of the lamp. The power supply voltage can also be changed.
Found in a 90s nHands On Electronics, this circuit triggers a relay that shuts off the load when...
This project was found in a 1982 publication, using only two transistors. Signal injectors are...
Designed by Philips in 1968 to control the washer water level this circuit uses components from the era....