General Description
If you are here, it means you wanna construct an infrared sensor to detect moving object.
Infrared sensors are used to detect movements of objects or objects placed in-front of the sensor.
The basic concept of the infrared sensor detector are as follows:
1) The IR transmitter LED emits IR signals in a direction
2) The signal transmitted is received at the IR receiver when the radiated signal bounces back from the surface of the object.
Functioning
Initially at power up, the IR transmitter starts emitting IR signals which bounces back at the photo diode, the photo diode conducts.
Vo is approximately 2v which is quite small to meet our requirements.
We will think of a comparator to compare two voltages, the input voltage Vo and a reference voltage.
Lm 358, having two internal OPAMPs, one will be use as a comparator for our sensor as shown below.
if V+ > V- , Vout = Vcc
if V+ < V-, Vout = 0V
A potentiometer, wired as a voltage divider will be used to set a reference voltage which will go a long way to set the distance rage too.
Specification
1) The functioning voltage is 5V
2) The output is digital (logic 0 and logic 1)
3) Low cost (less than CFA1000)
Application
1) Hobby projects like the famouse line follower robot
2) Self driving toy car
3) Obstacle detection robot
4) Automatic letter counter
5) Automatic sliding doors
6) Trespass detection and so on……
Tools and materials used for this project
1) IR Transmitter (5mm LED) X 1
2) IR receiver (5mm photodiode) X 1
3) 10k resistor X 1
4) 120 Ohms resistor X 1
5) 330 ohms resistor X 1
6) 10K potentiometer X 1
7) Lm 358 X 1
8) 8 pin IC socket
9) A soldering iron and some solder
10) Jumper wires and breadboard wires
11) Wire cutter
12) A breadboard
13) 4.318cm x 2.667cm copper board
14) Green and red LED (1 each)
Circuit diagram
Follow the circuit diagram above closely and wire all the components correctly on a breadboard. The go ahead and test its functioning.
If it functions as expected, GOOD! Move directly to construct the PCB.
You can follow my guide on how to design a PCB board on proteus design suite here.
Realization
Top silk
Bottom silk
Outputs that can be used includes;
1) Relays: Used to control high voltage appliances and devices like 220V lamps and electric motors when an object is detected.
2) Buzzer: Use to produce sound when an object is detected in security places.
3) Fan; Used to put ON/OFF a fan when someone is sited at a particular place for refreshments
LED: Used to follow a white line like in the case of a line follower robot.
Working Video
Coming soon…
Downloads
Download the complete project files in a zip folder here
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