This circuit is from an 80's Electronic Engineering. The base is a common operating and 4 single integrated voltage comparators. The circuit directly drives 4 indicator LEDs.
This simple photometer uses a 0-200 µA galvanometer as indicator. The sensor is a common LDR and...
This circuit is from the Motorola Linear Databook of 1990 and can be implemented with other...
This circuit triggers a warning oscillator if you forget the lights on when you leave the car. The...