A photoresistor or light dependent resistor is a component that is sensitive to light. When light falls upon it then the resistance changes. Values of the resistance of the LDR may change over many orders of magnitude the value of the resistance falling as the level of light increases. It is not uncommon for the values of resistance of an LDR or photoresistor to be several Megaohms in darkness and then to fall to a few hundred ohms in bright light. With such a wide variation in resistance, LDRs are easy to use and there are many LDR circuits available.

Here the LDR and R1 form a simple ‘Potential Divider’ circuit. When the light level decreases, the resistance of the LDR increases. When the resistance increases w.r.t to the other resistor having fixed resistance, the voltage drop across LDR increases.

Features:

• Coated with epoxy
• Good reliability
• High sensitivity
• Fast response
• Good spectrum characteristic

Specification:

• Diameter: 10mm
• Max Voltage: 500V
• Max power consumption: 500mW
• Operating Temperature: – 30 – +70°C
• Light Resistance: 5-100K ohm
• Dark Resistance: 1-8M ohm

Applications:

• Camera Automation
• Indoor Sunlight Control
• Industrial Control
• Optical Lamp
• Optical Control Music IC
• Optical Control Switch
• Photoelectric Control
• Annunciator
• Electronic toy
• Electronic Detector
• Switch
• Light control
• Light control lamp
• Photoelectric control
• Camera automaticphotometry