Ambient Light Sensor/Photo diode Amplifier Circuit

 

• The above circuit is used for adjusting the contrast of screens of devices like Mobile Phones based on the Ambient light available
• Ambient Light Sensor is used to sense the light
• 741 opamp is used as I to V converter
• The current through the diode is converted to voltage at the output
• The output of UA741 is an Analog output and is provided to an input of Microcontroller ADC
• The output voltage is proportional to the feedback resistor and current through diode
• The capacitor in the feedback helps to compensate for any capacitance on the inverting input
• The circuit can be modified for better performance under various operating scenarios