This project creates an automatic fan control system that turns on a ceiling or desk fan when someone enters a room and turns it off after they leave. It’s perfect for bathrooms, workshops, or any room where you want ventilation only when occupied.<\/p>\n
Difficulty:<\/strong> Beginner A PIR sensor detects when someone enters the room. When motion is detected, the system activates a relay that turns on the fan. After a set period of no motion (e.g., 5 minutes), the fan turns off automatically. An optional temperature sensor can also trigger the fan if the room gets too hot.<\/p>\n Important:<\/strong> Ceiling fans typically operate on 120V\/240V AC. Use a relay rated for the fan’s current (typically 0.5-1.5A). If you are not experienced with AC wiring, consult an electrician.<\/p>\n For DC fans (e.g., computer fans), the 5V relay can directly control them.<\/p>\n This automatic fan control system ensures ventilation only when needed, saving energy and reducing noise when rooms are empty. It’s perfect for bathrooms, workshops, and home offices.<\/p>\n","protected":false},"excerpt":{"rendered":" Project Overview This project creates an automatic fan control system that turns on a ceiling or desk fan when someone enters a room and turns it off after they leave. It’s perfect for bathrooms, workshops, or any room where you want ventilation only when occupied. Difficulty: Beginner Estimated time: 1-2 hours Estimated cost: $15-25 How […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9],"tags":[],"class_list":["post-3922","post","type-post","status-publish","format-standard","hentry","category-projects"],"blocksy_meta":[],"yoast_head":"\r\n
\nEstimated time:<\/strong> 1-2 hours
\nEstimated cost:<\/strong> $15-25<\/p>\nHow It Works<\/h2>\n
Materials Needed<\/h2>\n
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Circuit Diagram<\/h2>\n
Connection Table<\/h3>\n
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Component<\/th>\n Pin<\/th>\n Arduino Pin<\/th>\n<\/thead>\n \nPIR Sensor<\/th>\n VCC<\/th>\n 5V<\/th>\n PIR Sensor<\/th>\n GND<\/th>\n GND<\/th>\n PIR Sensor<\/th>\n OUT<\/th>\n Digital Pin 2<\/th>\n Relay Module<\/th>\n VCC<\/th>\n 5V<\/th>\n Relay Module<\/th>\n GND<\/th>\n GND<\/th>\n Relay Module<\/th>\n IN<\/th>\n Digital Pin 3<\/th>\n Status LED<\/th>\n Anode<\/th>\n Digital Pin 13 (through 220\u03a9)<\/th>\n Status LED<\/th>\n Cathode<\/th>\n GND<\/th>\n DHT22 (optional)<\/th>\n DATA<\/th>\n Digital Pin 4<\/th>\n<\/tbody>\n \n
Arduino Code<\/h2>\n
\/\/ Automatic Fan Control with PIR\n#include <DHT.h> \/\/ Include if using temperature sensor\n\nconst int pirPin = 2;\nconst int relayPin = 3;\nconst int ledPin = 13;\n\nunsigned long lastMotionTime = 0;\nconst unsigned long fanOffDelay = 300000; \/\/ 5 minutes\n\nbool fanOn = false;\n\n#ifdef USE_TEMP_SENSOR\n#define DHTTYPE DHT22\nconst int dhtPin = 4;\nDHT dht(dhtPin, DHTTYPE);\nconst float tempThreshold = 28.0; \/\/ Turn on if above 28\u00b0C\n#endif\n\nvoid setup() {\n Serial.begin(9600);\n \n pinMode(pirPin, INPUT);\n pinMode(relayPin, OUTPUT);\n pinMode(ledPin, OUTPUT);\n \n digitalWrite(relayPin, LOW);\n digitalWrite(ledPin, LOW);\n \n #ifdef USE_TEMP_SENSOR\n dht.begin();\n #endif\n \n Serial.println(\"Auto Fan Control Ready\");\n delay(60000); \/\/ PIR warm-up\n}\n\nvoid turnFanOn() {\n digitalWrite(relayPin, HIGH);\n digitalWrite(ledPin, HIGH);\n fanOn = true;\n lastMotionTime = millis();\n Serial.println(\"Fan ON\");\n}\n\nvoid turnFanOff() {\n digitalWrite(relayPin, LOW);\n digitalWrite(ledPin, LOW);\n fanOn = false;\n Serial.println(\"Fan OFF\");\n}\n\nvoid loop() {\n bool motion = digitalRead(pirPin) == HIGH;\n \n #ifdef USE_TEMP_SENSOR\n float temp = dht.readTemperature();\n if (!isnan(temp) && temp > tempThreshold) {\n if (!fanOn) {\n turnFanOn();\n }\n }\n #endif\n \n if (motion) {\n lastMotionTime = millis();\n if (!fanOn) {\n turnFanOn();\n }\n }\n \n if (fanOn && (millis() - lastMotionTime > fanOffDelay)) {\n #ifdef USE_TEMP_SENSOR\n \/\/ Only turn off if temperature is below threshold\n if (temp <= tempThreshold || isnan(temp)) {\n turnFanOff();\n } else {\n lastMotionTime = millis(); \/\/ Reset timer if still hot\n }\n #else\n turnFanOff();\n #endif\n }\n \n delay(100);\n}\n<\/code><\/pre>\nCeiling Fan Wiring Safety<\/h2>\n
Installation Steps<\/h2>\n
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Project Extensions<\/h2>\n
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Conclusion<\/h2>\n