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In general terms a buzzer may be understood as a device that can produce an audible tone in the influence of an externally applied voltage. This audible output may be either in the form of a buzzing or a beeping sound. The sound is created by inducing rapid movements in the diaphragm of the buzzer. In electronic buzzers these vibrations are made by an oscillator circuit which drives a piezo to produce the sound. In electromechanical buzzers these oscillations are self-made through a rapid switching of an electromagnet. The best example of an electromechanical buzzer is the call bell used in offices; the horn used in automobiles is another example of an electromechanical buzzer. Before learning how to make a buzzer, let’s first see how these electro- mechanical buzzers function.
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How Electromechanical Buzzers Function?
An electromagnet forms the main part of all types of electromechanical buzzers. These may be either AC operated or DC operated.
In AC buzzers, the AC Mains voltage is applied to an electromagnet coil. The alternating voltage induced in the coil generates a varying magnetic field in accordance to the applied voltage, which in turn vibrates an iron plate to produce the required audible buzzing sound.
In DC buzzers or horns as used in cars and other vehicles, when a DC battery voltage is applied to its electromagnet, it instantly pulls an iron diaphragm. But the DC supply to the coil is so arranged that when the diaphragm is pulled the supply is cut-OFF (see figure). Due to this the electromagnet is switched OFF, the diaphragm is released to its original position when again the DC supply is restored to repeat the cycle. This cycle repeats at a very high speed to generate the typical loud honk from it.
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How Electronic Buzzers Function?
Electronic buzzers mostly incorporate a piezo electric transducer as the diaphragm. They operate at very low currents and yet are able to produce high pitched, sharp beeping sounds. The heart of the circuit of most electronic buzzers is an electronic oscillator. The alternating voltage produced by the oscillator is dumped into an inductor which effectively converts these signals into high voltage pulses to drive the piezo and produce an audible note.
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How to Make a Simple Buzzer?
The circuit design of the electronic buzzer shown is amazingly simple in design and yet is able to produce a sound output that’s quite sharp to the ears. The construction procedure does not require much of explanation, as the whole circuit can be built within minutes with the help of the given schematic and the parts list.
The circuit description given below will surely help you to understand better regarding how to make a buzzer:
As can be seen in the circuit diagram, the circuit uses just one transistor, two resistors, a buzzer coil and a piezo- electric transducer. Here no external oscillator is required to drive the piezo, rather the circuit is a self oscillatory one. To maintain oscillations in an electronic circuit a feedback voltage is always required and here it is received through the centre tap of the piezo (thanks to these simple low cost 3-terminal transducers). The buzzer coil here performs the function of amplifying the low voltage oscillations into high voltage oscillations required by the piezo to create a strong audible tone. The resistor R1 is used just for providing the required biasing to the transistor, where as R2 has been included so that the oscillations do not stall due to overloading of the circuit.
Well, now you just don’t have to wonder how to make a homemade buzzer, as you simply know how to do it.
Piezo image credit:Busytrade.com
Black Cover Image Credit:Ringford.manufacturer