PIR motion sensors utilize built-in amplifiers and quad-type pyroelectric elements to detect infrared radiation, particularly from human body heat. They are designed to pick up even subtle movements and are effective due to their working principles that measure radiation changes rather than emitting signals. To avoid false detections, it is recommended to install them away from windows, HVAC vents, and at a height that minimizes activation from small pets and children.

1. • UNIQUE FEATURES
• OF
• PIR MOTION SENSORS

2. INTRODUCTION
They use built-in amplifier to
detect motion
The IR module is specifically used to detect IR
radiation (body heat) from the human body
They can also detect other
things that generate IR
radiation

3. INTERNAL COMPONENTS
A built-in amplifier to convert IR radiation to
voltage
A comparator for converting output to
digital form
A stabilized power supply unit to supply
power to the circuit
A quad-type pyroelectric element to
detect movement within its range

4. DETECTION OF MOVEMENT
The quad-type pyroelectric
element has 4 similar receptors The sensor can pick up even the
smallest movements within the
receptor’s range
This makes PIR motion sensors more accurate and effective

5. WORKING PRINCIPLES
IR motion sensors detect radiation
instead of emitting them
The inverting input becomes low
when the sensor detects IR radiation
Then the comparator’s output
increases and lights up the
LED
3 different resistors in the IC
transfer current to all internal
components

6. TYPES OF IR SENSORS
IR sensors are of different types depending on their usage
Temperature sensors
detect temperature
PIR sensors are used for
home/commercial
security
Ultrasonic sensors
can measure
distance between
two points

7. FOCUSING MECHANISM IN IR SENSORS
OR
PIR motion sensors use
LENS MIRROR
The main task of
lenses/mirrors is to
focus light onto the
sensor
Mirrors have
slightly more range
than lenses

8. HOW TO AVOID FALSE DETECTIONS
Avoid placing them on
the wall directly facing
the window
Avoid installing PIR
motion detectors near
HVAC vents that blow
cold/hot air
Install them high up
on the wall to avoid
being triggered by
toddlers and pets

9. THANK YOU