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Buzzer Overview

Date post:19-Jun-2015
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Reviews the two main buzzer technologies and two major circuit types, defines common specifications and typical applications, buzzer sample sounds, and introduces CUI's buzzer line. To view CUI's buzzer offering visit: http://www.cui.com/Catalog/Components/Buzzers
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  • 1. Buzzers1

2. IntroductionPurposeTo provide an overview of CUI Inc buzzersObjectives Introduce the two main buzzer technologies and their working principles Introduce the two major circuit types their working principles Introduce various options among CUIs buzzer line, including availablesound effects and mounting types Define common specificationsContent: 19 pages Introduce typical applicationsLearning Time: 20minutes 2 3. UsageTypical Usage Identification Signal AlarmHome Appliances Safety and Security Automotive Electronics Office Automation Medical Equipment Industrial Consumer Electronics 3 4. Piezo vs. Magnetic BuzzersPiezo Buzzers Wide operating voltage: 3250V Lower current consumption: less than 30mA Higher rated frequency Larger footprint Higher sound pressure levelMagnetic Buzzers Narrow operating voltage : 116V Higher current consumption : 30100mA Lower rated frequency Smaller footprint Lower sound pressure level4 5. Piezoelectric ElementStructure of a Piezoceramic ElementWithout Feedback type With Feedback type Feedback Piezoelectric Electrode ElectrodeMetal Plate Ceramics Adhesive5 6. Working Principle Extended StateA.C. Voltage Applied Compressed StateVibration creates sound wave6 7. Piezo Buzzer StructureTransducer (without driving circuitry) Casing Piezoceramic Element TerminalIndicator (with driving circuitry)CasingPiezoceramic ElementCircuit BoardTerminal7 8. Feedback The feedback line provides a voltage that is proportional tothe strain on the main piezo element. This voltage can be used to create a simple, self-oscillating,circuit.8 9. Magnetic BuzzersStructure of Magnetic BuzzerNo Name of Parts1Casing2Vibrating Weight3Cavity4Vibrating Disk5Magnet6Pole7Coil8Yoke Plate9PCB10 Transistor11 Epoxy12 Pin 9 10. Working Principle Vibrating disk Magnet Pole Coil Yoke Plate10 11. Indicators vs. TransducersIndicators Built-in driving circuit Simple to design-in Fixed frequencyTransducers External driving circuit required Complex to design-in User-selected frequency11 12. Key SpecificationsFrequency responseThe response of the system to an input with a constant amplitude but a varyingfrequency.Sound pressure level (Unit: dB Pa)Sound pressure level, SPL, is the deviation from atmospheric pressure caused bythe soundwave expressed in decibel Pascals. It is generally proportional to inputvoltage and decays by 6 dBs when doubling the distance from the buzzer.Resonant Frequency (Unit: Hz)Systems which vibrate have a frequency which they naturally tend to vibrate at.This is called the resonant frequency.Impedance (Unit: ohm)Electrical impedance is the ratio of applied voltage to current. The electricalimpedance varies with frequency. 12 13. dBs dB stands for decibel. It is not a unit, but rather a numeric scale. Values increase exponentially, instead of linearly as in countingnumbers. Expressed in normal numbers, 2 dB is ten times 1 dB. Allows for a huge range of values to be expressed in relativelylittle space. 13 14. Frequency Response A perfect audio transducer would recreate every frequency withoutattenuation or gain. There is no perfect transducer. Frequency response is a quantitative measurement of a devices abilityto recreate any frequency. 14 15. The Human Ear and A-Weighting Comparison of Different SPLsGenerally, most humans can Jet engine 632 Pa150 dB perceive frequencies from at 30 m 2020,000 Hz. Threshold of pain63.2130 dBHowever, the human ear is Hearing damage (possible)20 Pa Approx.120 dB more sensitive to some Jet at 100 m 6.32200 Pa 110140 db frequencies than others. Jack hammer at 1 m 2 PaApprox.100 dBA-weighting places more value Traffic on a busy roadway at 2x10-16.32x10-1 Pa 8090 dB on frequencies which the10 m human ear is more sensitive to. Passenger car at 10 m2x10-2210-1 Pa 6080 dBSome CUI buzzers specify SPLNormal conversation at 1 m 2x10-32x10-2 Pa4060 dB using the A-weight system. I.E. Very calm room 2x10-46.32x10-4 Pa 2030 dB dB AAuditory threshold at 1kHz 2x10-5 Pa (RMS) 0 dB15 16. Resonant Frequency The natural frequency a system tends to oscillate at. Driving a system at its resonant frequency will create the largestamplitudes with the smallest input. Buzzers are loudest when driven at their resonant frequency.16 17. Sound Effects A buzzer is usually used as a warning sound, i.e. car security, car reverseaid, home appliances, medical instruments, industrial equipments,notebook, camera, and etc. Sound Effects: click the sound icon to test the different sounds. Continuous (Feedback/ Warning Signal)High/Low Tone (Warning Signal)Slow/Fast Pulse (Feedback/ Warning Signal)Siren (Alarm)Chime (Door Bell) 17 18. Mounting ConfigurationsSurface mount PCB mount Panel mountVertical mount Snap-inWire leadsWire leads w/flange 18 19. Applications Home Automotive Medical AppliancesSecurity IndustrialOffice Automation19 20. Summary CUI Incs buzzers are used across a range of applications asindicators and alerts Two main technologies are used to generate sounds: magneticand piezoelectric Indicators include a built-in driving circuit while transducersrequire and external source to create a tone View CUIs buzzer product offering 20

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