5 Pieces HC-SR501 PIR Motion Detector Sensor Module -- Adjustable Sensitivity & Delay, Dual Trigger Modes, Arduino Compatible

Detect motion instantly with the HC-SR501 PIR Motion Detector Sensor Module -- the most popular passive infrared sensor for Arduino, ESP32, and Raspberry Pi projects. It detects the infrared heat signature of people, animals, and other warm objects up to 7 meters (21 feet) away across a 120° detection cone, and outputs a clean 3.3V digital signal that any microcontroller can read directly. Two onboard potentiometers let you adjust sensitivity and time delay, and a jumper selects between single and repeatable trigger modes. Three wires, no libraries, no calibration -- just connect and read.

🔧 How It Works

The HC-SR501 uses a pyroelectric sensor behind a Fresnel lens to detect changes in infrared radiation. When a warm object moves across the sensor's field of view, the BISS0001 IC outputs a clean digital HIGH (3.3V) signal.

• Motion detected: Output goes HIGH (3.3V) for the set time delay period.
• No motion: Output goes LOW (0V).
• Repeatable mode (H): Output stays HIGH as long as motion continues -- timer resets with each new detection.
• Single mode (L): One timed pulse per detection -- additional motion during the delay is ignored.

Pinout:

Pin order may vary between manufacturers. Always check the silkscreen labels on your module.

Onboard adjustments:

⚡ Key Features

• Wide Detection Range: 3m to 7m (9ft to 21ft), adjustable via onboard potentiometer.
• Wide Detection Angle: ~120° cone from the Fresnel lens -- covers an entire room or hallway.
• Adjustable Time Delay: 3 seconds to 5 minutes -- set how long the output stays HIGH after detection.
• Dual Trigger Modes: Jumper-selectable Single (L) or Repeatable (H). Repeatable keeps output HIGH as long as motion continues.
• Simple Digital Output: 3.3V HIGH / 0V LOW -- compatible with 3.3V and 5V logic, no level shifting needed.
• Wide Operating Voltage: 5V to 20V DC -- works with USB, batteries, and a wide range of supplies.
• Ultra-Low Power: Only 65µA quiescent current -- ideal for battery-powered projects.
• No Libraries Needed: Uses a single digitalRead() -- works immediately with basic Arduino code.
• Compact: 32mm × 24mm PCB with 23mm Fresnel lens dome.

📐 Specifications

📦 What's in the Box

• 5x HC-SR501 PIR Motion Detector Sensor Module (with Fresnel lens installed)

Arduino, jumper wires, breadboard, and power supply are not included.

🛒 What You'll Need

• Microcontroller -- Arduino Uno/Mega/Nano, ESP32, Raspberry Pi, or any board with a digital input
• 3 × jumper wires -- to connect VCC, OUT, and GND
• USB cable -- to program your Arduino and view serial output
• Small screwdriver -- to adjust the sensitivity and time delay potentiometers
• (Optional) 10µF–100µF electrolytic + 0.1µF ceramic capacitor -- for filtering power supply noise and reducing false triggers

🔌 Compatible With

• Arduino Uno, Mega, Nano, Leonardo -- direct connection, read with any digital pin
• ESP32 / ESP8266 -- 3.3V output safe for ESP GPIO. Power from VIN or external 5V (not 3.3V rail)
• Raspberry Pi -- 3.3V output safe for Pi GPIO. Power from 5V pin (Pin 2/4)
• STM32, AVR, PIC, and any microcontroller with a digital input
• Standalone -- output can directly drive a small LED, relay module, or buzzer without a microcontroller

🎯 Typical Applications

• Automatic lighting -- hallway, bathroom, closet, porch, and stairway lights
• Security alarms -- trigger buzzers, sirens, or notifications on motion
• Smart home / Home Assistant -- connect via ESP32 or Pi for automations
• Occupancy detection -- HVAC control, energy saving, meeting room availability
• People counting -- approximate count using single trigger mode
• Pet detection -- automatic feeders, pet doors, activity monitoring
• Halloween props -- trigger animatronics, sound effects, or lighting
• Wildlife cameras -- activate a camera when an animal passes by
• Automatic fan control -- turn on ventilation when someone enters a room
• Arduino and STEM projects -- teach digital input, sensor integration, and automation

💡 Tip -- Reducing False Triggers: If you experience random activations, add a 10µF–100µF electrolytic capacitor and a 0.1µF ceramic capacitor across the VCC and GND pins directly at the sensor. This filters power supply noise and is the single most effective fix. Full details in our User Guide at the Envistia Mall product support center.

⚠️ Important Notes

• 30–60 second warm-up required. The sensor outputs random signals after power-up while it stabilizes. Always include a warm-up delay in your code.
• Output is always 3.3V regardless of supply voltage. This is normal and compatible with all common microcontrollers.
• Minimum supply voltage is 5V. The module will not work reliably at 3.3V.
• Detects motion, not presence. A person standing perfectly still will not continue to trigger the sensor.
• Glass blocks infrared. The sensor cannot detect motion through glass windows.
• ~2.5-second blockage time after each trigger cycle -- the sensor cannot re-trigger during this period.
• Pin order varies between manufacturers. Always check the silkscreen labels on your specific module before wiring.
• Not weatherproof. Use an enclosure with an IR-transparent window for outdoor installations.
• The Fresnel lens is soft plastic -- handle carefully to avoid scratches that reduce sensitivity.
• ESP32/WiFi users: RF interference can cause false triggers. Add filtering capacitors and mount the sensor away from the WiFi antenna.

🏪 About Envistia Mall

Envistia Mall is a US-based electronics retailer specializing in development boards, sensors, modules, and components for makers, engineers, and educators. We ship from the United States with fast handling times. Product documentation and technical support are available at our dedicated support site.

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