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.
Found in American documentation from the 1970s, this circuit is intended for amplifying analog TV...
This circuit produces horizontal lines or bars in a analog TV tuned between channels 2 and 5. L1...
This alarm with the 555 integrated circuit is from an EDN from the 90s. The circuit directly...