HC-SR501 PIR Motion Sensor Module — Adjustable Sensitivity and Delay
The HC-SR501 is the standard passive infrared motion sensor for Arduino projects, detecting human body heat movement up to 7 metres in a 120° cone. Unlike the AM312, it has two adjustable potentiometers: one for detection range (3m–7m), one for output hold time (0.3–18 seconds). A jumper selects between retriggerable mode (output resets on repeated detection) and single-trigger mode (output fires once and ignores further motion until the hold time expires).
- 7 metre detection range — adjustable from 3m via potentiometer
- 120° detection cone
- Adjustable hold time — 0.3 to 18 seconds
- Retriggerable or single-trigger mode — jumper selectable
- 5V–20V supply — works from 5V Arduino or 12V supply
- Digital high output on detection — direct Arduino GPIO input
| Specification | Value |
|---|---|
| Supply voltage | 5V – 20V |
| Detection range | 3m – 7m (potentiometer adjustable) |
| Detection angle | 120° |
| Hold time | 0.3s – 18s (potentiometer adjustable) |
| Output | Digital HIGH (3.3V) on detection |
| Warm-up time | 30–60 seconds after power-on |
Why does the HC-SR501 need 30–60 seconds to initialise?
The PIR sensor element needs to reach thermal equilibrium with the environment before reliable detection begins. During warm-up, the output may trigger falsely. Account for this in your code — ignore outputs for the first 60 seconds after power-on, or use a flag variable that enables detection only after the warm-up period.
Best for
Motion-activated lights, intruder alarm sensors, automatic door openers, energy-saving occupancy switches, driveway alerts, letterbox detectors, and any application needing adjustable-range motion sensing from 3 to 7 metres.
Why Kunkune
Shipped from UK stock. 60-day returns, no minimum order. Fast Royal Mail delivery.
For 3.3V microcontrollers or tight enclosures, the AM312 mini PIR sensor runs directly from 3.3V and measures just 10×23mm.
Buying in bulk? For orders of 10+ units, contact us for trade pricing.
