LDR (Light Dependent Resistors)

LDR light dependent resistors are variable resistors that are controlled by light. The resistance of an LDR decreases as the intensity of light increases. They are also known as photo resistors, and are usually used in light or dark-activated switching circuits, or light sensitive detector circuits.




LDR light dependent resistors are made of a high-resistance semiconductor, which absorbs photons until bound electrons are able to jump the conduction band. The free electrons conduct electricity and therefore lower resistance.




What are light dependent resistors used for?


LDRs have many practical applications in situations in which the resistance needs to change depending on the amount of light available. For example, they can be found in alarm devices, light meters in cameras, and in outdoor solar-powered lighting.




Types of light dependent resistors


LDRs may differ by their range of resistance and their sensitivity. The two key types are intrinsic and extrinsic:



  • In intrinsic LDRs, photons must jump the entire bandgap, so they need to gain more energy before the resistance will decrease.

  • Extrinsic LDRs have impurities, which means the electrons don't need to jump as far, making them more sensitive to lower energy photons.


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RS Stock No. 914-6714
Mfr. Part No.NORPS-12
TWD91
Each (In a Pack of 4)
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5.4 kΩ 1MΩ 55ms 45ms CdS 2 Through Hole TO-18 - - - 12.6kΩ 75°C -60°C
RS Stock No. 466-1902
Mfr. Part No.NSL-4512
TWD55
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- - - - - 2 Through Hole TO-5 - - - - +75°C -60°C
RS Stock No. 466-1924
Mfr. Part No.NSL-4532
TWD35
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- - - - - 2 Through Hole TO-5 - - - - +75°C -60°C
RS Stock No. 466-1996
Mfr. Part No.NSL-6112
TWD37
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170Ω 1.3MΩ - - CdSe 2 Through Hole TO-18 4.45 x 3.81 x 1.78mm 1.78mm 4.45mm 2kΩ +75°C -60°C
RS Stock No. 914-6710
Mfr. Part No.NSL-19M51
TWD37
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20 kΩ 20MΩ 55ms 45ms CdS 2 Through Hole TO-18 - - - 100kΩ 75°C -60°C
New
RS Stock No. 466-1952
Mfr. Part No.NSL-5542
TWD57
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- - - - - 2 Through Hole TO-5 - - - - +75°C -60°C
RS Stock No. 466-1974
Mfr. Part No.NSL-5152
TWD36
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170Ω 5MΩ - - CdS 2 Through Hole TO-18 4.45 x 3.81 x 1.78mm 1.78mm 4.45mm 2kΩ +75°C -60°C
RS Stock No. 466-1968
Mfr. Part No.NSL-5112
TWD36
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700Ω 0.67MΩ - - CdS 2 Through Hole TO-18 4.45 x 3.81 x 1.78mm 1.78mm 4.45mm 10kΩ +75°C -60°C
RS Stock No. 2508662397
Mfr. Part No.NSL-5160
BrandSilonex
TWD113
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RS Stock No. 2508662145
Mfr. Part No.NSL-4960
BrandSilonex
TWD193
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RS Stock No. 2508662599
Mfr. Part No.NSL-4140
BrandSilonex
TWD113
Each
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RS Stock No. 2508662381
Mfr. Part No.NSL-5510
BrandSilonex
TWD135
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RS Stock No. 2508662224
Mfr. Part No.NSL-5150
BrandSilonex
TWD113
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RS Stock No. 2508662577
Mfr. Part No.NSL-5110
BrandSilonex
TWD113
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RS Stock No. 2508662791
Mfr. Part No.NSL-7910
BrandSilonex
TWD164
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RS Stock No. 2508662347
Mfr. Part No.NSL-6910
BrandSilonex
TWD278
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RS Stock No. 2508662640
Mfr. Part No.NSL-6940
BrandSilonex
TWD169
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