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HC-SR501 PIR Sensor (Passive Infrared Sensor) + IR Proximity Sensor

HC-SR501 PIR Sensor (Passive Infrared Sensor) + IR Proximity Sensor

β‚Ή92.00Price

πŸ” 1. HC-SR501 PIR Sensor (Motion Detection)

πŸ“Œ What it does

  • Detects human/animal movement

  • Works based on body heat (infrared radiation)

πŸ‘‰ It does NOT detect objects, only motion of warm bodies

βš™οΈ Key Specifications

  • Voltage: 4.5V – 20V

  • Output: Digital HIGH (3.3V) when motion detected

  • Range: ~3 to 7 meters

  • Angle: ~110°–120Β°

  • Delay time: 5s – 300s adjustable

🧠 Features

  • βœ”οΈ Adjustable sensitivity + delay

  • βœ”οΈ Two modes:

    • Repeatable (keeps detecting)

    • Non-repeatable

  • βœ”οΈ Very low power (<50Β΅A standby)

  • βœ”οΈ Uses Fresnel lens for wide detection

πŸ”Œ Pinout

  • VCC β†’ 5V

  • GND β†’ GND

  • OUT β†’ Digital pin

πŸ’‘ Applications

  • 🚨 Security systems

  • πŸ’‘ Automatic lights

  • 🏠 Smart home automation

  • πŸ‘£ Human presence detection

⚠️ Important Notes

  • Needs 30–60 sec warm-up

  • Cannot detect stationary person

  • Sensitive to heat changes

πŸ” 2. IR Proximity Sensor (Obstacle Detection)

πŸ“Œ What it does

  • Detects objects (any material)

  • Works using IR reflection

βš™οΈ Key Specifications

  • Voltage: 3.3V – 5V

  • Range: ~2 cm – 30 cm

  • Output: Digital LOW when obstacle detected

  • IC: LM393 comparator

🧠 Features

  • βœ”οΈ Adjustable detection distance

  • βœ”οΈ Fast response

  • βœ”οΈ Works for any object (not just humans)

  • βœ”οΈ Cheap & simple

πŸ”Œ Pinout

  • VCC β†’ 3.3V / 5V

  • GND β†’ GND

  • OUT β†’ Digital pin

πŸ’‘ Applications

  • πŸ€– Obstacle avoiding robot

  • πŸ“¦ Object detection

  • πŸ“ Line following robot

  • πŸš— Smart vehicles

βš–οΈ PIR vs IR Sensor (VERY IMPORTANT)

FeaturePIR SensorIR Sensor
DetectsHuman motionAny object
RangeLong (3–7m)Short (2–30cm)
TypeMotion sensorProximity sensor
Works onBody heatIR reflection
AccuracyGood for motionGood for distance (short)

🧠 When to use which

πŸ‘‰ Use PIR if:

  • You want human detection

  • Example: automatic light ON when someone enters

πŸ‘‰ Use IR if:

  • You want object detection

  • Example: robot avoiding obstacles

πŸ”₯ Pro Tip (Very Useful)

πŸ‘‰ Combine BOTH sensors:

  • PIR β†’ detect human presence

  • IR β†’ detect distance/obstacle

➑️ Used in:

  • Smart robots

  • Smart doors

  • Advanced IoT systems

⚠️ Common Beginner Mistakes

  • PIR not working β†’ didn’t wait warm-up time

  • IR giving false output β†’ not adjusted potentiometer

  • Using PIR for object detection ❌ (wrong sensor choice)

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