The operational amplifier and the sensor used in this National Semiconductor circuit are not common today, but the configuration can be adapted to use current components.
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...