| Symptom | Likely Cause | Better Fix | | :--- | :--- | :--- | | | 1. Continuous false trigger 2. Time delay set too long | Reduce sensitivity (turn SENS pot CCW). Remove nearby heat sources (WiFi routers, direct sunlight). | | Output always LOW | 1. No power 2. Stabilization period active 3. Dead sensor | Wait 30-60 seconds after power-up – the sensor calibrates. Measure voltage between VCC and GND. | | Detects but stays on forever | Jumper in repeatable mode + continuous motion | This is normal. Alternatively, switch jumper to Single mode (H) to force a fixed OFF time. | | Detects motion from outside (pets/cars) | Sensitivity too high OR lens pointing through glass | Turn sensitivity down to 30%. Mask parts of the Fresnel lens with tape (black electrical tape works best). | | Random triggering when AC turns on | Power supply noise | Add 100µF & 0.1µF capacitors across VCC/GND. Use a dedicated 5V regulator (not the Arduino 5V pin). |
The is a highly popular, low-cost Passive Infrared (PIR) motion sensor module , frequently identified as a variant of the widely used HC-SR501 . It is a "passive" device, meaning it does not emit energy but instead detects changes in infrared radiation (heat) emitted by humans or animals moving within its field of view. Technical Specifications
| Symptom | Likely Cause | Better Fix | | :--- | :--- | :--- | | | 1. Continuous false trigger 2. Time delay set too long | Reduce sensitivity (turn SENS pot CCW). Remove nearby heat sources (WiFi routers, direct sunlight). | | Output always LOW | 1. No power 2. Stabilization period active 3. Dead sensor | Wait 30-60 seconds after power-up – the sensor calibrates. Measure voltage between VCC and GND. | | Detects but stays on forever | Jumper in repeatable mode + continuous motion | This is normal. Alternatively, switch jumper to Single mode (H) to force a fixed OFF time. | | Detects motion from outside (pets/cars) | Sensitivity too high OR lens pointing through glass | Turn sensitivity down to 30%. Mask parts of the Fresnel lens with tape (black electrical tape works best). | | Random triggering when AC turns on | Power supply noise | Add 100µF & 0.1µF capacitors across VCC/GND. Use a dedicated 5V regulator (not the Arduino 5V pin). |
The is a highly popular, low-cost Passive Infrared (PIR) motion sensor module , frequently identified as a variant of the widely used HC-SR501 . It is a "passive" device, meaning it does not emit energy but instead detects changes in infrared radiation (heat) emitted by humans or animals moving within its field of view. Technical Specifications
