This is a simple circuit that activates an alarm when there is a knock on the door or there are any vibrations due to movement of heavy goods or furniture. The circuit uses readily available components. Circuit and working The circuit is built around quad-opamp LM IC1 , which is configured in amplifier mode. It uses the piezoelectric element of a piezo buzzer as the input sensor, two transistors BC T1 through T2 , a piezo buzzer and some other components for the alarm circuit. The reference voltage at pin 3 of IC1 is set by trimming potmeter VR1.

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The piezoelectric crystal converts physical parameters such as pressure, strain or force to a corresponding electrical charge. If any vibration occurs, proportional rate of electrical potential induces across the piezo terminals. The analog read pin compares the induced voltage with a reference value. If the voltage induced is greater than the reference threshold value the Alarm will ON. The alarm remains ON for 10 seconds after the triggering. Change the value of delay function to adjust the ON time of the alarm.

The speaker is connected to pin 9 on the arduino board. An LED for the visual indication is added to the pin The sensitivity of the device can be varied by adjusting the threshold value. Vibration sensor arduino alarm Code. Here a theft attempt or burglar entry is detected by sensing the vibration produced during the action, which is sensed by the piezoelectric sensor.

This theft alert system can be used for multiple purposes. It can use wherever a theft attempt can be detected by means of vibration. The analog input value will be in proportional to the intensity of the vibration over the piezo sensor. The electrical signal from the piezoelectric sensor compares with a preset reference threshold value. And when the input value is above the threshold, the Arduino executes the AT command sketch to call the given number.

In the program, the threshold value has already set to The threshold value should be adjusted, so as to trigger the device based on the level of vibration that may be occurred during the theft attempts. A smaller threshold value makes the device to respond even for minute vibrations. So a threshold value should be set to avoid unwanted triggers and to detect wanted triggers.

The piezo sensor should be placed, where the chance of vibration is high or where enough vibration will be produced. For easy and better placing, the sensor can be placed apart from the GSM and Arduino circuit. The wires should not be too long as it may drop the induced voltage.

So always try to reduce the wire length as much as possible. After dialing, there is a delay of 30 seconds before the termination of the call.

So, even the call has terminated at the receiver end the next call will be dialed only for a triggering after 30 seconds. That is the device always makes the call alert if any triggering vibration occurs after 30 seconds from the last triggering. To stop the alert completely, the user has to power off the device. March 23, March 17, December 29, Your email address will not be published.

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Door-Knock or Vibration Alarm

Security systems are designed for detecting the intrusion and unauthorized entry into the residential houses, commercial buildings, industries, and military surroundings. In our day-to-day life, security systems for home is a major concern to protect from burglary, property, and self defense from intruders. Generally, security systems for home can be designed using different technologies. Alarm security systems for home, alarm security system integrated with closed-circuit television surveillance, and so on. Different types of security systems for home can be designed using different types of sensors such as motion sensors, sound sensors, vibration sensors, and so on. Basically, security systems for home are designed using maximum number of sensors for the detection of intruders.


Security Systems For Home Using Door Knock Vibration Alarm

Abstract In this modern world everyone wants something new, something different, so instead of using a switch to ring the door bell just an alarm is produced by knocking the door which people feel more luxurious. The circuit of automatic alarm on knocking uses a thin piezoelectric plate, senses the vibration generated on knocking a surface such as a door or a table to activate the alarm and can also be used to safeguard motor vehicles. The piezoelectric plate is used as the sensor. It consist IC Timer to which speaker is connected at the output. Piezoelectric material is used at the input in order to convert any mechanical vibration into electrical variation, it avoids false triggering. The plate can be fixed on a door, cash box, cupboard, etc using adhesive. A

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