Door Open Alarm Circuit with Hall Effect Sensor

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Introduction

In the current era where everything relies on technology, using a simple lock key for security is ideally backward. Even the intruders of today’s world use technology. Therefore, we must have to use some kind of lock circuits that can secure homes, offices, banks, lockers, and places that needs security. And, not just secure it but also enable the user to get the update or news through the alarm when anyone passes by. Hence magnetic reed switch can be used for this purpose. So, in this tutorial, we are going to make a” Door Open Alarm Circuit using Hall effect Sensor “. Hall effect sensors are basically the most common method of measuring magnetic field and therefore are popular and widely used in so many different applications.

Hardware Required

S.no	Component	Value	Qty
1.	Timer IC	LM555	1
2.	IC	A1302UA	1
3.	Speaker	8Ω/0.5W	1
4.	Small Magnet	–	1
5.	Ceramic Capacitor	0.01uF, 0.04uF	1, 1
6.	Electrolytic Capacitor	33uF/16V	1
7.	Resistor	100Ω, 1KΩ, 51KΩ, 43Ω	1, 1, 1, 1
8.	Battery	9V	2

Circuit Diagram

door-open-alarm-circuit-using-Hall-effect-sensor-diagram-schematic

Working Explanation

In this Door, an Open Alarm Circuit using Hall effect Sensor is working as a switch while the timer IC is wired to generate pulse oscillations. Throughout the near magnet situation, the hall effect sensor serves as an open switch and there would be no voltage at pin 4 (Reset) of an IC. During the far magnet situation, the hall effect sensor works as a close switch and provides the output voltage near Vcc. In that case, Reset pin 4 becomes biased. Since this Reset pin of IC 555 is an active low pin, therefore, timer IC starts to Oscillate the pulse signal. Timer IC is connected to the loudspeaker, Output pulse duration depends on Resistors R2, R3, and Capacitor C1. By adjusting the values of these components you can get different sound tones at the loudspeaker.