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LDR (Photoresistor) for Beginners in Electronics

Created on: 30 July 2012

A LDR (Light Dependent Resistor) or photoresistor is a resistor that will change its resistance, depending on how much light is shining on it. As the light intensity on the LDR increases, so the resistance of the LDR decreases.

Schematic symbols for a LDR or photoresistor are shown below:

Schematic symbols for a LDR or photoresistor
LDR / Photoresistor Symbol used in Circuit Diagrams

This photo shows what physical LDRs look like.

Light dependent resistors
Light Dependent Resistors (LDRs)

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