![]() including 1 feedback-electrode ( the central, small electrode joined with red wire in this photo), and an oscillator to self-drive the buzzer.Ī piezoelectric buzzer/beeper also depends on acoustic cavity resonance or Helmholtz resonance to produce an audible beep. ![]() Interior of a readymade loudspeaker, showing a piezoelectric-disk-beeper (With 3 electrodes. Sounds commonly used to indicate that a button has been pressed are a click, a ring or a beep. Piezoelectric Piezoelectric disk beeperĪ piezoelectric element may be driven by an oscillating electronic circuit or other audio signal source, driven with a piezoelectric audio amplifier. The word "buzzer" comes from the rasping noise that electromechanical buzzers made.Ī joy buzzer is an example of a purely mechanical buzzer and they require drivers. Similarly, a relay may be connected to interrupt its own actuating current, causing the contacts to buzz (the contacts buzz at line frequency if powered by alternating current) Often these units were anchored to a wall or ceiling to use it as a sounding board. Types Electromechanical Įarly devices were based on an electromechanical system identical to an electric bell without the metal gong. In 1951, they established the Barium Titanate Application Research Committee, which allowed the companies to be "competitively cooperative" and bring about several piezoelectric innovations and inventions. This advancement mainly came about because of cooperative efforts by Japanese manufacturing companies. R2 can probably be a lot lower, but again, you didn't supply a datasheet so all the component values are just rough ideas or guesses at best.Piezoelectric buzzers, or piezo buzzers, as they are sometimes called, were invented by Japanese manufacturers and fitted into a wide array of products during the 1970s to 1980s. R2 cause some back voltage to this current to make it die down more quickly, helping the high frequecy response. If you don't give the kickback current a place to go, then the voltage can get high enough to fry Q1. Piezo elements have a significant inductive component as viewed from the driving circuit. Figure you can count on a gain of 50, so that means 215 mA of collector current, which should be way more than required.ĭ1 is there to give the kickback current of SP1 a place to go when Q1 turns off suddenly. When the digital output is high, Q1 will have 4.3 mA of base current, which should easily give it enough current sink capability to pull the collector as low as it can go. You most likely don't need as much base drive as this. Most digital outputs can source that much without issue. Figure the B-E junction drops 700 mV, so that leaves 4.3 V accross R1, which causes 4.3 mA base current and will draw that much from the digital output. R1 limits the current thru the base of Q1 when the digital output is high. The above circuit should work well enough for most piezo speakers, although it can possibly be driven from a higher voltage, which would yield higher volume. The page you linked to turned out not to be a datasheet, so we don't know anything more about the piezo speaker than what you say. ![]() You said you were a novice, so here is something simple: Is this correct? Is it possible to build a drive circuit for a piezo buzzer with only these components, or do I something else? The supplementary comments for this circuit diagram suggested people "consider connecting a Zener diode in parallel with the piezoelectric sound component and Rp if necessary."īased on this, my understanding is that the necessary components of this drive circuit are - the microcomputer, I am a novice with electrical engineering and I am trying to understand exactly what components are needed in this external drive piezo buzzer drive circuit. Under the heading "Please give me an example of the drive circuit for a Piezoelectric Sounder or a Piezoelectric Diaphragm (External Drive Type)." they said "Examples of typical drive circuits are broadly divided into case 1 where a transistor circuit is used and case 2 where the product is driven directly from a microcomputer." and gave the following image as an example. I was reading the FAQ page on the website of a piezo buzzer manufacturer ![]() ![]() I am interested in the use of a microcomputer in a drive circuit for an external drive piezo buzzer. ![]()
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