4mm Dia CdS Photoconductive Photocell Photoresistor Light Sensor 540nm For Camera Exposure

Typical Applications

Description

Cadmium Sulfoselenide (CdS) sensors are low cost photoconductive devices for visible light measurement. Their resistance decreases as the light level increases with efficiency characteristics similar to the human eye.

The GM45 Series are (CdS), Photoconductive photocells designed to sense light from 400 to 700 nm. These light dependent resistors are available in a wide range of resistance values. They’re packaged in a two leaded plastic-coated ceramic header.

Specification

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Features

Visible light response
Sintered construction
Low cost

Application Example

Input Boards LDR:

This is a ORP13, 4mm light dependent resistor
Fully covered resistance of 10kΩ
In normal room conditions it has a resistance of approximately 250Ω.

Design Considerations

Photoresistors are less light-sensitive devices than photodiodes or phototransistors: the two latter components are true semiconductor devices, while a photoresistor is a passive component and does not have a PN-junction. The photoresistivity of any photoresistor may vary widely depending on ambient temperature, making them unsuitable for applications requiring precise measurement of or sensitivity to light photons.

Photoresistors also exhibit a certain degree of latency between exposure to light and the subsequent decrease in resistance, usually around 10 milliseconds. The lag time when going from lit to dark environments is even greater, often as long as one second. This property makes them unsuitable for sensing rapidly flashing lights, but is sometimes used to smooth the response of audio signal compression.