This simple Bargraph photometer with 4 LEDs was found in a 1997 documentation. The scale is adjusted in a trimpot and the sensor can be any common LDR. Power can be supplied by cells or battery.
We found this circuit in Motorola's 1990 Linear Databook. The component used is unusual. The...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This 80's circuit, suggested in Texas Insrtruments documentation, uses a Hall effect sensor. The...