Sound Alarm Circuit

Posted on Feb 6, 2014

This is a circuit that will go off if the circuit detects any sound above a certain threshold. Once the circuit detects sound, the alarm goes off alerting us to this sound. This circuit has extreme use when an area ordinarily should be very quiet and should have no sound like a quiet zone. Under quiet conditions, with little to no sound, the alarm

Sound Alarm Circuit
Click here to download the full size of the above Circuit.

will not go off. When a sound is detected such as someone walking through the room or talking in a room, the alarm will go off. Thus, we can detect intruders in a room that shouldn`t be there if they create sound while operating in a room where there shouldn`t be any. So in order to build our circuit, we will use a microphone and connect it to an audio amplifier to get amplified signals. The amplifier IC that we use is the popular LM386 IC. This IC will amplify the output signals that the microphone produces so that the arduino will be able to detect large enough signals to interpret them. All we need to do then is connect the 3 terminals on the board, which are VCC, GND, and AUD. Vcc is the power which we supply to the breakout board, so that the microphone and amplifier have sufficient power to operate. GND is the negative or return path of the power. And AUD is the output of the microphone board, which are the amplified sound signals. Using this board greatly simplifies the process of building our sound alarm circuit, since we don`t have to put the electret microphone and amplifier together. However, if you do want to do so, do so. Again, click the above link to the circuit schematic. Before we show the complete schematic diagram of the arduino sound alarm circuit, we will first show the pinout of the LM386. This way, the connections that we make from the microphone to it will make more sense. Terminals 1 and 8...

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