Light Intensity Meter Using Ldr

The circuit is very simple and convenient using only a few ldr variable resistor transistor and meter components.

Light intensity meter using ldr.

Measuring light using light sensor. Working of ldr controlled led using arduino. It s made up of such material whose conductivity varies as per light falls on it. Ldr are used most of times to detect presence of light or for measuring the intensity of light.

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. This is an instructable on our class project about measuring light using a light sensor. This basic light intensity meter circuit can be used in a wide range of electronic projects and experiments to calculate the light intensities. Light intensity meter using at89c52 microcontroller.

It works on the principle of photoconductivity. 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. The circuit utilizes an analog meter of 0 to 10 volts.

The voltage divider output is feed to the analog pin of the arduino. 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. In order to detect the intensity of light or darkness we use a sensor called an ldr light dependent resistor. As per the circuit diagram we have made a voltage divider circuit using ldr and 100k resistor.

We previously made many circuits using ldr which use ldr to automate the lights according to requirement. 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.