A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR- based motion detectors. PIR sensors are commonly used in security alarms and automatic lighting applications. PIR sensors detect general movement, but do not give information on who or what moved. For that purpose, an active IR sensor is required.
Step 1: Theory
PIR sensors are commonly called simply "PIR", or sometimes "PID", for "passive infrared detector". The term passive refers to the fact that PIR devices do not radiate energy for detection purposes. They work entirely by detecting infrared radiation (radiant heat) emitted by or reflected from objects.
Pin Diagram of PIR Sensor
Pin 1 – GND Pin 2 – Output Pin 3 – VCC(+5V) Modes of Operations
This sensor has two modes of operations:
1. Single Trigger Mode To select Single Trigger mode, the jumper setting on PIR sensor must be set on LOW. In case of Single Triggered Mode, Output goes HIGH when motion is detected. After specific delay the output goes to LOW even if the object is in motion. The output is LOW for some time and again goes HIGH if object remains in motion. This delay is provided by user using the potentiometer. This potentiometer is on board of PIR sensor module. In this way, the PIR sensor gives HIGH/LOW pulses if object is in continuous motion.
2. Repeat Trigger Mode To select Repeat Trigger mode, the jumper setting on PIR sensor must be set on HIGH. In case of Repeat Triggered Mode, Output goes HIGH when motion is detected. The output of PIR sensor is HIGH until the object is in motion. When object stops motion, or disappears from the sensor area, the PIR continues its HIGH state up to some specified delay (tsel). We can provide this delay (tsel) by adjusting the potentiometer. This potentiometer is on board of PIR sensor module. In this way, the PIR sensor gives HIGH pulse if object is in continuous motion.
Changing Sensitivity and Delay time
There are two potentiometers on PIR motion sensors board: Sensitivity Adjust and Time delay adjust. It is possible to make PIR more sensitive or Non-Sensitive Enough. The maximum sensitivity can be achieved up to 6 meters. Time Delay Adjust potentiometer is used to adjust the timetsel shown in diagrams. Clockwise Movement makes PIR more Sensitive. Two things are important while manufacturing PIR sensor: Low cost and High Sensitivity. Both these things can be magically achieved by using Lens cap. The lenses increase range of operation; increases sensitivity and change pattern of Sensing vary easily.
Step 2: Component Requirement
1. 5 Volt DC power supply
2. Zero PCB
3. PIR Motion Sensor
4. Two pin Connector as shown in figure (Red)
5. Female connector strip
6. SPDT Switch
7. 5/6 Volt Relay
8. 1K Resistor
9. BC 547 Transistor
10. Bulb with Holder
Step 3: Project Video Link
Step 4: Circuit Diagram
Assemble the circuit as per the circuit diagram shown above.
Step 5: For More........
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