1|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
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
www.researchdesignlab.com
2|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
Pin Details
Pin Name Details
1 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 any
application.
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 with
increasing 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 kΩ fixed resistor which is tied to
+5V. Hence the voltage value in this case decreases with increase in light intensity.
www.researchdesignlab.com
3|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
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 kΩ …(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.
www.researchdesignlab.com
4|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
Sample Application: In this application depending upon intensity of light a
lamp is on or off.
www.researchdesignlab.com
5|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
/* void main()
* Project name: {
LIGHT sensor LAMP=0;
* Copyright DELAY();
(c) Researchdesignlab.com while(1)
* Description: {
if(LDR==1)
* Test configuration:
LAMP=1;
MCU: AT89S52
DELAY();
Dev.Board: 8051
}
Oscillator: 11.0592 MHz
else
Software: Keil uVision3
{
*/ LAMP=0;
#include<reg51.h>
}
sbit LDR=P1^0; }
sbit LAMP=P2^0;
void DELAY() }
{ //delay of 3ms
unsigned int X=800000;
while(X--);
www.researchdesignlab.com
6|P ag e An ISO 9001-2008 Certified Company
DIGITAL LIGHT INTENSITY SENSOR Order Code RDL/PSB/13/001/V1.0
Board Dimensions
40.64mm
25.4mm
To buy this product click the below link
http://researchdesignlab.com/index.php/sensors/light-intensity-sensor.html
www.researchdesignlab.com
