Buzzers and it's function
What is a buzzer? This article explains what a buzzer is in in-depth detail. You will get information about the types of buzzers and their functional uses.
Electro-mechanical buzzer
A buzzer is in the mechanical form of a small rectangular or cylindrical housing, with electrical connection for direct mounting on rigid printed circuit, or with electrical connection consisting of flexible electrical son. In the latter case, the buzzer has two small brackets. The loudness of such a component is about 85 dB / cm (note that it does not specify the sound level meter - as for HP, as a business perspective, it would seem probably too little power. As for sweets which are given the price per 100g and not for one kilogram).
It requires a DC voltage to operate, it should generally be between 3 V and 28 V, depending on the model. A buzzer designed to operate at 6 V generally works very well for any supply voltage between 4 V and 8 V, and a buzzer designed to operate at 12 V can work perfectly at a voltage between 6 V and 28 V (see characteristics given by the manufacturer for not making stupidity). There are also buzzers that work directly on the AC mains 230 V. This type of buzzer is convenient to use, because unlike piezoelectric buzzers simple (simple piezoelectric transducers without associated electronics), it has no work, except of course the eventual control stage which will enable it. He provides a simple DC voltage and presto, it sounds.
Simple Piezo-electric:- A buzzer (transducer) piezoelectric requires an AC voltage to operate, a few volts to several tens of volts (3V to 30V for example). It presents an optimal resonance frequency a few kHz (between 1 kHz and 5 kHz in general, eg, 2 kHz, 2.8 kHz or 3 kHz). It is this type of transducer that can be found on the back of the watch with an alarm function.
Unlike the electro-mechanical buzzer seen before, this component requires some electronics to generate the AC signal it needs to function. So use an oscillator responsible for generating a square wave signal whose frequency is matched to the resonant frequency of the transducer, oscillator can easily be built with logic gates or transistors. If we apply the piezoelectric transducer a signal on one of its terminals, and the same signal but out of phase on its other terminal, it will be able to deliver a power quad, with a supply voltage identical (mounting bridge, same principle as that adopted for certain audio amplifiers power).
Warning
A piezoelectric transducer is reversible: it produces a sound when one applies an alternating voltage, and outputs a voltage periodic damped when tapped. The second feature is useful to use as a vibration sensor (placed on an acoustic drum, it helps with some additional electronics, trigger another sound), but can be dangerous to the electronics that control because the tension he is capable of delivering upon impact may amount to several tens of volts. It is therefore imperative not to "rush" when used as a sound generator, if one wants his control stage live long. You can always try to "capture" the energy that provides the transducer when struck, this is what I tried - without much convincing results it must be admitted.Piezoelectric buzzer with integrated oscillator
It is simply the assembly in a single housing, a piezoelectric transducer and an electronic control (square-wave signal generator). Everything is then supplied with a simple DC voltage, usually between 3V and 20V, and requires a current of 10 mA and 30 mA (buzzer consumption depends mainly on the voltage used). The implementation of such a buzzer becomes as easy as using a electromechanical buzzer. Some beepers "electronic" with integrated oscillator, producing a continuous sound, while others produce a sound interrupted (chopped).
Source of images: own camera clicked pictures.