This circuit activates a relay when the supply voltage drops below the value set in the trimpot. The transistors can be the BC548 and BC558 and the 6 V relay. The circuit was found in a 1999 Poptronics.
The circuit we have just described has been mounted in the car of the author of the project for...
This circuit was found in an old European publication, but it can be implemented with more modern...
This circuit is based on a PLL 566 and generates positive ramps. The frequency depends on Rx and C...