Datasheet Better — Hw416b Pir Sensor

HW416B OUT → 1kΩ resistor → Base of BC547 Emitter of BC547 → GND Collector → Relay coil negative terminal Relay coil positive → VCC (with flyback diode) The stock fresnel lens is cheap plastic. You can upgrade the lens with a universal PIR lens (e.g., from a KC7783R) to achieve the claimed 7 meters. Also, the sensor is less sensitive to motion moving directly toward it versus moving across its field of view.

void loop() if (motionDetected) digitalWrite(LED_PIN, HIGH); Serial.println("Motion detected!"); motionDetected = false; lastMotionTime = millis(); hw416b pir sensor datasheet better

In your microcontroller code, wait at least 30 seconds after boot before reading the sensor, or add a manual reset using a transistor to short the output low during startup. Problem C: Weak Output Driving The HW416B cannot directly power a relay, buzzer, or LED strip (it will drop voltage drastically). HW416B OUT → 1kΩ resistor → Base of

void setup() Serial.begin(9600); pinMode(PIR_PIN, INPUT); pinMode(LED_PIN, OUTPUT); void loop() if (motionDetected) digitalWrite(LED_PIN