Introduction: LIGHT DETECTOR
In this tutorial we will see how to make a simple light dector using Operational amplifier.Operational amplifier generally use in many purposes which includes summing,difference,average amplifier.etc.lets get started.
Here we have connected Reference voltage of 3.3v to inverting terminal for comparing with voltage at non inverting input.Initially the Volatge at inverting terminal will be high compare to non inverting termainal so output voltage will -VCC.When the light falls on ldr the resistance decrease and max current will flow to 22k resistor hence increases above reference voltage and led is on.
make sure vcc is high compare to both voltage at input terminals.
Resistor value may have to be change depending on environment light.