Light Intensity Meter Using Ldr

This is an instructable on our class project about measuring light using a light sensor.

Light intensity meter using ldr.

It s made up of such material whose conductivity varies as per light falls on it. At the end of this instructable you will be able to build a working circuit and program an ldr light sensor to be able to read sunlight and print it on your com. The voltage divider output is feed to the analog pin of the arduino. The circuit utilizes an analog meter of 0 to 10 volts.

Light intensity meter using at89c52 microcontroller. The light sensor for a lux meter can be one of several different types of sensors including photodiodes and phototransistors but the easiest to use and often the most readily available type of sensor is a photoresistor or light dependent resistor ldr. Ldr are used most of times to detect presence of light or for measuring the intensity of light. So the led does not light.

The circuit is very simple and convenient using only a few ldr variable resistor transistor and meter components. There are different types of ldr as shown in above figure and each have different specifications. Working of ldr controlled led using arduino. We previously made many circuits using ldr which use ldr to automate the lights according to requirement.

The ldr is a special type of resistor that allows higher voltages to pass through it low resistance whenever there is a high intensity of light and passes a low voltage high resistance whenever it is dark. We all know that ldr light dependent resistor can be used as one of the most suitable light intensity detector because of its working principle. This basic light intensity meter circuit can be used in a wide range of electronic projects and experiments to calculate the light intensities. However when the light intensity onto the ldr is high then the resistance of the ldr is low so current flows onto the base of the first transistor and then the second transistor consequently the led lights here a preset resistor is used to turn up or down to increase or decrease the resistance.

Typically an ldr will have 1mω 2mω at total darkness 10 20kω at 10 lux 2 5kω at 100 lux. In order to detect the intensity of light or darkness we use a sensor called an ldr light dependent resistor.