This circuit was found in a 1971s English magazine. We can still assemble it using BC548 transistor. The other components are common. The supply voltage of 6 or 12 V depends only on the relay.
This circuit was found in an English publication from the 80's. It triggers a buzzer (with...
The SN72741 integrated circuit is nothing more than the version of Texas Instruments of the known...
This simple circuit connects in external battery to a load when the AC Power line fails. S1 can be...