Light sensitive resistor Φ10mm photoresistor, 560nm LDR resistor

Description:

A photoresistor (or light-dependent resistor, LDR, or photo-conductive cell) is a light-controlled variable resistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity. A photoresistor can be applied in light-sensitive detector circuits, and light-activated and dark-activated switching circuits.

A photoresistor is made of a high resistance semiconductor. In the dark, a photoresistor can have a resistance as high as several megohms (MΩ), while in the light, a photoresistor can have a resistance as low as a few hundred ohms.

Specifications:

Working principle:

when light falls on LDR i.e. when photons fall on LDR, valence band electrons get sufficient energy to get excited to the conduction band. Incident photons must have energy greater than the forbidden energy gap of the semiconductor. When light having enough energy falls on the device, more electrons will get excited to conduction band. As the number of free electrons increases, more current flows through the circuit. Hence it is said that, as light falls on LDR, resistance decreases.

Application:

Photoresistors come in many types. Inexpensive cadmium sulfide cells can be found in many consumer items such as camera light meters, clock radios, alarm devices (as the detector for a light beam), nightlights, outdoor clocks, solar street lamps and solar road studs, etc.

Photoresistors can be placed in streetlights to control when the light is on. Ambient light falling on the photoresistor causes the streetlight to turn off. Thus energy is saved by ensuring the light is only on during hours of darkness.

They are also used in some dynamic compressors together with a small incandescent or neon lamp, or light-emitting diode to control gain reduction. A common usage of this application can be found in many guitar amplifiers that incorporate an onboard tremolo effect, as the oscillating light patterns control the level of signal running through the amp circuit.

Test condition:

• Light resistance: Irradiated by 400-600Lux light for two hours, then test with 10Lux under standard light source A (as colour temperature 2856K)
• Dark resistance: Refer to the resistance 10 seconds after the 10Lux light is shut up.

• γ value: Logarithm of the ratio of the standard resistance value under 10 Lux and that under 100Lux.
• R10, R100 are the resistances under 10Lux and 100Lux respectiverly.
• Max. power consumption: Maximum power at the environmental temperature 25℃.
• Max. external voltage: Maximum voltage to be continuously given to component in the dark.

Dimension:(mm)

Temperature-Property:

Spectrum Response Characteristic: