# what is LDR and how does it work?

what is ldr and how does it work?.  Do you know what is LDR? How does LDR work? LDR stands for Ligh dependendt resistor. Ldr Is a type of resistor whose resistance value can vary almost the same as a potentiometer

the difference is that the LDR resistance value changes due to the change in the intensity of the light it receives

If viewed from the physical form ldr has 2 feet with a sensor on its surface

More about the understanding and workings of LDR will be explained in the article below

## what is LDR?

because LDR is sensitive to light then LDR is widely used in lighting that can turn on automatically at night 2 days and automatically turn off during the day

as for the physical form of ldr is as follows

The physical form ldr has 2 legs

## how does LDR work?

How does LDR work is when the dark conditions ldr resistance value is very large even exceed 1 M

while in the light conditions its resistance is only a few Ohm only

This characteristic is used for lights on the sidewalks

In dark conditions the lights will light while in the light conditions the light will die by itself and this happens automatically

In the automatic light circuit there is an NPN transistor that is active if the base transistor is given a positive voltage even though the base voltage

for the collector’s feet connected to the relay to the positive pole while the collector’s leg is connected to the negative pole

read also the difference between NPN and PNP transistors

The base leg is connected to the resistor to the positive pole otherwise the base foot is also connected to the LDR to the negative pole

When the light is dark then the LDR resistance is so high it allows the base foot to flow so that the transistor is active and activate the relay so that the lamp connected to the relay is on

While the bright conditions of LDR resistance are very low it makes the current toward the base will be attracted towards the LDR

the current flowing into the LDR then towards the negative pole thus causing the base on the transistor to die and the relay off and the lights off

The above conditions occur automatically so it does not require a manual switch to turn on the lights

Thus the article on what is ldr and how does it work

read also simple variable power supply circuit