What is Light Dependent Resistor (LDR) ?

A Light Dependent Resistor (LDR) or a photo resistor is a device whose resistivity is a function of the incident electromagnetic radiation. Hence, they are light sensitive devices. They are also called as photo conductors, photo conductive cells or simply photocells.

They are made up of semiconductor materials having high resistance. There are many different symbols used to indicate a LDR, one of the most commonly used symbol is shown in the figure below. The arrow indicates light falling on it.

Applications of LDR

LDR’s have low cost and simple structure. They are often used as light sensor. They are used when there is a need to detect absences or presences of light like in a camera light meter. Used in street lamps, alarm clock, burglar alarm circuits, light intensity meters, for counting the packages moving on a conveyor belt, etc.

Bakit po mas mura yung sensor ng LDR compare sa ibang sensors?

Kasi hindi naman ganon kamahal yung mga ginamit na materials sa kanya and para lang sya sa mga maliliit na application.

what is LDR calibration?

how to calibrate LDR?

Hindi naman po ba ito madaling masira, katulad ng sa street lights, tuwing malakas ang ulan, paano ito nakakaapekto sa LDR?

How to make an LDR sensor circuit?

Can it sense other outdoor light conditions aside from direct sunlight? What if its already morning pero makulimlim?

pandagrrrr wrote:what is LDR calibration?

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You can calibrate the sensitivity of the LDR by changing the Resistor in its circuit. high resistance of resistor the more its sensitive.

judedominguiano wrote:Hindi naman po ba ito madaling masira, katulad ng sa street lights, tuwing malakas ang ulan, paano ito nakakaapekto sa LDR?

Kung sa quality hindi naman. sa tingin kong makakasira lang sa kanya eh yung kalawang.

pandagrrrr wrote:How to make an LDR sensor circuit?

okay. tomorrow i will give or post it here

ndreanicoke wrote:Can it sense other outdoor light conditions aside from direct sunlight? What if its already morning pero makulimlim?

Maybe it can sense other outdoor light like the light from a car but it depends on how sensitive your resistor is.

What if its already morning pero makulimlim? - what do you mean by this? gagawa ka ba street lights na bbukas lang kapag madilim na ?

do light sensors are the same with ldr sensors?

I am looking forward to seeing some projects using LDR sensor in this forum. Thanks

pandagrrrr wrote:do light sensors are the same with ldr sensors?

YES. They are same.

what if a homogeneous material(like a crystal ball) is placed between a flash light/light source and a ldr, will the ldr still sense the light source?

Ano po limitations ng LDR sensor?

Accurate po ba yung reponse time ng LDR?

pag nag LDR po ba kaylangan din ng speed?

Nadedetect po ba ng LDR yung LED's? or pwede ba gamitin yung sensor na to tapos idedetect nya yung ilaw ng LED?

sir.... is this LDR sensor is sensitive pin or not ?

sir this sensor , with what range can achieve?

Annyeong Dadagdagan ko lang po yung tanong ni margs Hanngang anong range po yung nasesense ng LDR saka po is it necessary po ba na kada isang LED is isang LDR sensor and transistor din po ? Kamsahamnida

Sir, ano pa po ba kayang gawin ng ldr? Bukod po dun sa kapag natamaan ng light ung sensor is mamamatay yung ilaw sa LED and vice versa. Thankyou po!