Electronics & Software – Tips & Guide


What is a light dependent resistor

What is a light dependent resistor?

a ldr is a photo-conductive material. when the light is exposed to ldr, the electromagnetic radiation is sufficient to excite the electrons towards the conduction band, thus increasing the conductivity. as a result, the resistance decreases

a useful component that detects light and operates another circuit. Typical example: turn on the light of your home when the sun goes down and turn it off when the sun rises again. the component reduces its resistance to light. Suppose you have a rc coupled amplifier and you have replaced one of its voltage divider bias resistor components with an ldr. then you too can shift the q point of the amplifier when the light falling on the ldr changes.

ldr is still available, although made from a substance often forbidden cadmium in a sup-hide.

The optical response is somewhat similar to the human response. it often extends over 3 to 4 decades of r 1 m in a current of darkness for nearly 3 decades in lux. best tolerance, dynamic range and optical filtered response in a buffered silicon photodiode from panasonic.

a light-dependent resistor (ldr) is a type of resistor that modifies the resistance across its terminals, depending on the intensity of the incident light. Usually, when there is total darkness around the ldr, which means a very low or no light intensity on the ldr, the resistance across the ldr is very high (it can range from a few kilo ohms to a few megohms). and, when there is adequate light around the ldr, which means that a good amount of light intensity is incident on the ldr, the resistance across the ldr terminals is low (maybe in a few kilo ohms or even be less than the kilo ohm interval).

ldr finds great applications as a light detection device and it is used in circuits for which we want feedback or any output based on the light intensity of the environment.

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