Digital Light Intensity Sensor

8/13/2019 Digital Light Intensity Sensor

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1 | P a g e A n I S O 9 0 0 1 - 2 0 0 8 C e r t i f i e d C o m p a n y

DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0

www.researchdesignlab.com

Digital Light Intensity Sensor

Light Dependent Resistor (LDR), suitable

for use in projects which require a device or circuit to

be automatically switched on or off in darkness or

light. As the amount of light falling on this LDR

increases, its resistance decreases. The light detector

itself is just 5mm in diameter. Module triple output

mode, digital outputs simple, analog output more

accurate, serial output with exact readings.

Features

Wide spectral response. Low cost. Wide ambient temperature range. Module triple output mode, digital output is simple, analog output more

accurate, serial output with exact readings.

Applications

Ambient light sensing Proximity sensing

Specifications

Parameter Value

Operating Voltage +5v dc regulated

Light intensity Digital value is indicated by out pin


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Pin Details

Pin Name Details1 out Active high output

2 +5v Power supply

3 gnd Power supply gnd

4 rx receiver

5 tx transmitter

6 gnd Power supply gnd

Using The Sensor

Connect +5v to pin 2 and ground to pin 5 and 6. Pin 4 and 5 should be connected to particular transmitter and receiver pin of

controller.

Output pin may be connected to any port pins and can be used to anyapplication.

Working

An LDR and a normal resistor are wired in series across a voltage,

as shown in the circuit below. Depending on which is tied to the 5V and

which to 0V, the voltage at the point between them, call it the sensor node,

will either rise or fall with increasing light. If the LDR is the component

tied directly to the 5V, the sensor node will increase in voltage withincreasing light The LDR's resistance can reach 10 k ohms in dark

conditions and about 100 ohms in full brightness. The circuit used for

sensing light in our system uses a 10 k fixed resistor which is tied to

+5V. Hence the voltage value in this case decreases with increase in l ight intensity.


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The sensor node voltage is compared with the threshold voltages for

different levels of light intensity corresponding to the four conditions-

Optimum, dim, dark and night. The relationship between the

resistance RL and light intensity Lux for a typical LDR is:

RL = 500 / Lux k (3.1)

With the LDR connected to 5V through a 10K resistor, the output voltage

of the

LDR is:

Vo = 5*RL / (RL+10) (3.2)

In order to increase the sensitivity of the sensor we must reduce the value

of the fixed resistor in series with the sensor. This may be done by putting

other resistors in parallel with it.


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Sample Application: In this application depending upon intensity of light a

lamp is on or off.


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/*

* Project name:

LIGHT sensor

* Copyright

(c) Researchdesignlab.com

* Description:

* Test configuration:

MCU: AT89S52

Dev.Board: 8051

Oscillator: 11.0592 MHz

Software: Keil uVision3

*/

#include

sbit LDR=P1^0;

sbit LAMP=P2^0;

void DELAY()

{ //delay of 3ms

unsigned int X=800000;

while(X--);

}

void main()

{

LAMP=0;

DELAY();

while(1)

{

if(LDR==1)

LAMP=1;

DELAY();

}

else

{

LAMP=0;

}

}

}


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Board Dimensions

40.64mm

25.4mm

To buy this product click the below link

http://researchdesignlab.com/index.php/sensors/light-intensity-sensor.html
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Digital Light Intensity Sensor