The amount of current generated by bending a speaker is extremely small and short, so there isn’t much that we can do with it, but it’s an interesting experiment. Using the same mechanism as a microphone, we have proof that bending a piezoelectric speaker (in the case of a mic this is equal to receiving a vibration in the air) results in the creation of a current. Picture 1 Bending the speaker causes the LED to light upīy doing this, we can see that the LED lights up. By the way, speakers don’t have a positive/negative direction. The speaker that we’ll be using this time takes an electric current to excite the piezoelectric elements and cause a metal plate to vibrate thus producing sound. But with an LED connected to the speaker, try bending the speaker. A speaker converts current to vibrations in the air, and a mic takes vibrations in the air and converts them into current for use as an audio signal. Roughly speaking, a mic is a type of speaker. But, let’s take a step back first and consider how a microphone works. We’ll be working with speakers this time. On figure 2, you can see the general mechanism of a dynamic speaker. In both cases, by supplying a current in accordance with a signal of the sound to be output, the speaker causes vibrations in the air, and produces sound.įigure 2 Dynamic speaker mechanism Difference Between Speaker and Microphone The piezoelectric type that we’ll be using is shown in figure 1. But regarding how electric signals are processed, they can be classified as: dynamic, condenser, piezoelectric, discharge (ion), magnetic, and ribbon. When it comes to classifying speakers, there are many types of shapes. But electronically speaking, what exactly is a speaker? Everyone has a general sense that electricity flows through them, causing vibrations that lead to the sound generation, but let’s look into the process of sound creation in more detail. This time, we’ll be dealing with speakers. Arduino (Arduino Uno R3 /Arduino Pro Mini). Arduino comes with a “tone” function and it’s relatively easy to get started with. Let’s see how sound works with Arduino by creating a simple instrument gadget. So always try to reduce the wire length as much as possible.This time, we’ll examine “sound” using Arduino with speakers. The wires should not be too long as it may drop the induced voltage. For easy and better placing, the sensor can be placed apart from the GSM and Arduino circuit. The piezo sensor should be placed, where the chance of vibration is high or where enough vibration will be produced. So a threshold value should be set to avoid unwanted triggers and to detect wanted triggers. A smaller threshold value makes the device to respond even for minute vibrations. 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. In the program, the threshold value has already set to 50. The sensitivity of the device can be adjusted by changing the value of the variable ‘threshold’. And when the input value is above the threshold, the Arduino executes the AT command sketch to call the given number. The electrical signal from the piezoelectric sensor compares with a preset reference (threshold) value. The analog input value will be in proportional to the intensity of the vibration over the piezo sensor. Refer: GSM module Hardware interface with Arduino It can use wherever a theft attempt can be detected by means of vibration. This theft alert system can be used for multiple purposes. Here a theft attempt or burglar entry is detected by sensing the vibration produced during the action, which is sensed by the piezoelectric sensor. Vibration sensor arduino alarm Code const int threshold = 50 void setup ( ) GSM Based Home Security Alarm SystemĪ GSM home security system alerts you by a phone call when any theft attempt or similar triggering action is sensed by the device. The threshold should be set to an optimum value, which can ignore minute vibrations and at the same time it doesn’t need any heavy vibrations for triggering. The sensitivity of the device can be varied by adjusting the threshold value. An LED for the visual indication is added to the pin10. The tone function of the arduino is used to generate the alarm ( arduino tone generator). The speaker is connected to pin 9 on the arduino board.
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