Motion Detector Alarm Circuit

Posted on Feb 5, 2014

This is an alarm circuit which will go off when any motion or movement is detected. Once it detects this motion, the circuit will trigger an alarm buzzer to sound which will remain on until the power is disconnected from the circuit. This alarm circuit`s most common use is to detect a person moving through an area where the motion detector can sen

Motion Detector Alarm Circuit
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se. Before this, we built a simpler motion detector circuit that turned on an LED once motion was detected. But 1 or 2 seconds after, the LED would go off. The difference between that circuit and this one which we`re now building is that an alarm must stay on once it is activated until it is manually turned off such as by shutting off all power. If an alarm just went off once and stopped, it wouldn`t be very much of an alarm. Once motion is detected with this circuit, it will turn on the buzzer, which will buzz until the circuit is manually disconnected. This is similar to an alarm only shutting off when a homeowner enters in the password to turn it off. A very good buzzer which can be used is a 1. 5-3V metal buzzer which can be found at allelectronics. com. This is a very low-voltage buzzer which only needs 1. 5V to 3V to operate. However, you can use any buzzer that can operate at 5V of power or less. If you only have buzzers that need more voltage, then you`ll have to power the buzzer with an external power source. Instead of connecting the anode of the buzzer to the 5V terminal of the arduino, you would connect it to an external voltage source, giving it the necessary voltage the buzzer would need. The main electronic component we will use that allows us to pick up this detection is the PIR motion sensor. The PIR motion sensor is a sensor which detects movement through picking up infrared waves. Being that a person...

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