0 Light Detector using LED

Led is usually used as lighting indicator and display. This electronic device emits light when electricity is flowing across it. Aside from the conventional use, LED can be used also as light detector. The simple circuit below is a schematic of the detector.

schematic diagram

741 pinouts

Part List:
LED - ordinary green LED (see LED pinout for more info)
IC - LM741 or any similar op-amps
VM - volt meter
R - 3.3 Mega ohms resistor 1/4W
Bat - two pcs 9V battery