Hall Sensor Alarm
i will show you how you can make a simple security alarm using hall sensor.
hall sensors is used in many field like automaotive,dc motors,cellphone magnetic flip cover. i got mine from a old dusty pc
![00.png](/proxy/?url=https://content.instructables.com/FUX/LGE1/JEIV65JB/FUXLGE1JEIV65JB.png&filename=00.png)
PARTS
1. HALL SENSOR FROM PC FAN
2.BUZZER
3. BATTERY
4. LED'S [OPTIONAL]
5. MAGNET
![11.png](/proxy/?url=https://content.instructables.com/FLI/PSVA/JEIV670N/FLIPSVAJEIV670N.png&filename=11.png)
take a pc fan apply some brute force and open it
![22.png](/proxy/?url=https://content.instructables.com/F3M/YC4B/JEIV67EX/F3MYC4BJEIV67EX.png&filename=22.png)
inside you will get sensor these are positive and negetive pins in middile two pins are output pins
![33.png](/proxy/?url=https://content.instructables.com/FRU/H5UW/JEIV67UN/FRUH5UWJEIV67UN.png&filename=33.png)
built a buzzer circuit (led's are optional)yellow wire will be connected to positive,two black wire will receive output and red wire is from buzzer it will be connected with one of output.
![44.png](/proxy/?url=https://content.instructables.com/FKX/URVP/JEIV68QW/FKXURVPJEIV68QW.png&filename=44.png)
here is the complete circuit diagram again led's are optional for better understanding check datasheet of sensor
![55.png](/proxy/?url=https://content.instructables.com/F44/AR3W/JEIV694S/F44AR3WJEIV694S.png&filename=55.png)
lets test the circuit when it sense a magnetic field it gets high to low and buzzer gets off
![66.png](/proxy/?url=https://content.instructables.com/F1I/2TFM/JEIV698J/F1I2TFMJEIV698J.png&filename=66.png)