Buzzers          1
IntroductionPurposeTo provide an overview of CUI Inc buzzersObjectives• Introduce the two main buzzer technologies and the...
UsageTypical Usage• Identification Signal• AlarmHome Appliances• Safety and Security• Automotive Electronics• Office Autom...
Piezo vs. Magnetic BuzzersPiezo Buzzers• Wide operating voltage: 3–250V• Lower current consumption: less than 30mA• Higher...
Piezoelectric ElementStructure of a Piezoceramic Element                      Without Feedback type               With Fee...
Working Principle   Extended State                          A.C. Voltage Applied   Compressed State                       ...
Piezo Buzzer StructureTransducer (without driving circuitry)                                         Casing               ...
Feedback• The feedback line provides a voltage that is proportional to  the strain on the main piezo element.• This voltag...
Magnetic BuzzersStructure of Magnetic BuzzerNo     Name of Parts1      Casing2      Vibrating Weight3      Cavity4      Vi...
Working Principle   Vibrating disk   Magnet           Pole   Coil   Yoke Plate                                  10
Indicators vs. TransducersIndicators• Built-in driving circuit• Simple to design-in• Fixed frequencyTransducers• External ...
Key SpecificationsFrequency responseThe response of the system to an input with a constant amplitude but a varyingfrequenc...
dB’s•   dB stands for decibel.•   It is not a unit, but rather a numeric scale.•   Values increase exponentially, instead ...
Frequency Response•   A perfect audio transducer would recreate every frequency without    attenuation or gain. There is n...
The Human Ear and A-Weighting                                       Comparison of Different SPL’s•    Generally, most huma...
Resonant Frequency•   The natural frequency a system tends to oscillate at.•   Driving a system at its resonant frequency ...
Sound Effects•   A buzzer is usually used as a warning sound, i.e. car security, car reverse    aid, home appliances, medi...
Mounting Configurations  Surface mount       PCB mount       Panel mount  Vertical mount       Snap-in        Wire leadsWi...
Applications     Home       Automotive           Medical   Appliances    Security     Industrial        Office Automation ...
Summary•   CUI Inc’s buzzers are used across a range of applications as    indicators and alerts•   Two main technologies ...
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Buzzer Overview

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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

Published in: Education, Business, Technology
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  • In this presentation, we will present an overview of CUI Inc’s buzzer product line, including a description of the main technologies used, their working principles, key specifications, and possible applications.
  • Buzzers are typically used for identification and alarm purposes across many major industries.
  • CUI’s buzzer line utilizes two main technologies. Each technology has specific characteristics that must be taken into consideration depending on the end user’s application requirements. Piezo buzzers offer a wider operating voltage range, a lower current consumption, a higher rated frequency, a higher SPL level, and are generally larger than magnetic buzzers. Magnetic buzzers are typically used in portable applications because they offer a smaller footprint. However, there are tradeoffs. When compared with piezo technology, magnetic buzzers have a narrow operating voltage range, a higher current consumption, and lower available frequency and SPL levels.
  • At the heart of all piezo-type buzzers is the piezoelectric element. The piezoelectric element is composed of a piezoelectric ceramic and a metal plate held together with adhesive. Both sides of the piezoelectric ceramic plate contain an electrode for electrical conduction. Piezo materials exhibit a specific phenomenon known as the piezoelectric effect and the reverse piezoelectric effect. Exposure to mechanical strain will cause the material to develop an electric field, and vice versa.
  • When an alternating voltage is applied to the piezoceramic element, the element extends and shrinks diametrically. This characteristic of piezoelectric material is utilized to make the ceramic plate vibrate rapidly to generate sound waves.
  • There are two types of piezo buzzers- transducers and indicators. Transducers consist of a casing, a piezoceramic element and a terminal. In order to operate a transducer, the user must send a square wave signal to the buzzer. Indicators consist of a casing, a piezoceramic element, a circuit board and a terminal. In order to operate an indicator, the user must send the buzzer a specified DC voltage.
  • Some CUI Inc piezo buzzers include a feedback line. Driving circuits for buzzers with feedback tend to be simpler than circuits for those without. Feedback is accomplished by dividing the piezo element into two, electrically isolated, pieces. When the main piezo element is actuated it squeezes the feedback portion, creating a voltage on the feedback line. A simple way to use feedback is to have the feedback line connected to the base of a transistor. As the piezo element oscillates the feedback signal will oscillate and the transistor will alternately block or allow current to flow.
  • This illustration highlights the structure of a typical magnetic buzzer. Like piezo technology, magnetic buzzers are available in transducer and indicator configurations. In a magnetic buzzer, the transistor acts as the driving circuit. Indicators include the transistor, creating a tone when a dc voltage is applied. Transducers lack this transitor, requiring a square wave signal to operate properly.
  • The vibrating disk in a magnetic buzzer is attracted to the pole by the magnetic field. When an oscillating signal is moved through the coil, it produces a fluctuating magnetic field which vibrates the disk at a frequency equal to that of the drive signal.
  • As mentioned earlier in the presentation, piezo and magnetic indicators have the driving circuitry built into the design, creating a “plug and play” solution. Because of this, engineers do not need to worry about building a complex circuit to drive the buzzer. The disadvantage, however, is that indicators operate on a fixed frequency, reducing the flexibility offered to achieve an alternate frequency as application requirements change. Transducers, on the other hand, do not have the driving circuit built-in, so engineers are offered a greater range of flexibility when designing their circuit. The downside comes in the fact that transducers do require an external driving signal to operate properly, potentially adding complexity and time to the design cycle.
  • Listed above are key buzzer specifications and their definitions - Frequency Response, Sound Pressure Level, Resonant Frequency, and Impedance.
  • A decibel is the scaled logarithm of the ratio of a measured value with respect to a reference value. Decibels are useful because they can show a huge range of values in a small space. For instance a sound pressure scale going from 0-120 dB can represent sound pressures from 20 μPa (micro-pascals) to 120,000,000 μPa. This roughly represents the lowest SPL a human can hear all the way up to uncomfortably loud sounds. Note: The generally accepted value for “Pref” in the formula above is 20 μPa.
  • In a perfect world all devices would recreate every frequency at the exact same amplitude. In real life every device will have frequencies which it may amplify and frequencies which it will tend to reduce or attenuate. Frequency response curves show how a particular device responds to each frequency. SPL is plotted against frequency to indicate how the device will handle certain frequencies. Note: frequency is plotted on an exponential basis, similar to dB’s, it allows the full range of human hearing to be fit in a compact space.
  • 20 Hz to 20 kHz tends to be the general range for human ears. This range is reduced with age, especially in males. In older males 13 kHz tends to be the upper end of the audible range. The human ear does not have a flat frequency response over the audible range. Certain frequencies tend to be attenuated while others are magnified. A-weighting attempts to compensate for this by discounting frequencies which the human ear is less sensitive to. It places priority on sounds between 1 kHz and 7 kHz.
  • Every system has a particular frequency that it tends to vibrate at. For instance, if you pluck a string on a guitar that string will vibrate very near, or at, its resonant frequency. By driving a system at its resonant frequency, very large displacements, relative to the input signal strength can be achieved. Driving a buzzer with an input signal which has the same frequency as the buzzer’s resonant frequency, will create the greatest SPL with the least input power.
  • Buzzers are implemented across many applications, usually to act as a warning signal. Click on the sound icons to sample common sound effects available in the CUI buzzer line.
  • CUI’s buzzers are available in various mounting configurations depending on the application need, including SMT, PCB pin, wire lead, snap-in, vertical mount and panel mount.
  • Buzzers are used across many industries. The major application categories that utilize buzzers for indication or alert purposes include: home appliances, automotive electronics, medical, safety and security, industrial, and office automation.
  • Buzzer Overview

    1. 1. Buzzers 1
    2. 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 CUI’s buzzer line, including available sound effects and mounting types• Define common specifications Content: 19 pages• Introduce typical applications Learning Time: 20 minutes 2
    3. 3. UsageTypical Usage• Identification Signal• AlarmHome Appliances• Safety and Security• Automotive Electronics• Office Automation• Medical Equipment• Industrial• Consumer Electronics 3
    4. 4. Piezo vs. Magnetic BuzzersPiezo Buzzers• Wide operating voltage: 3–250V• Lower current consumption: less than 30mA• Higher rated frequency• Larger footprint• Higher sound pressure levelMagnetic Buzzers• Narrow operating voltage : 1–16V• Higher current consumption : 30–100mA• Lower rated frequency• Smaller footprint• Lower sound pressure level 4
    5. 5. Piezoelectric ElementStructure of a Piezoceramic Element Without Feedback type With Feedback type Feedback Piezoelectric Electrode Electrode Metal Plate Ceramics Adhesive 5
    6. 6. Working Principle Extended State A.C. Voltage Applied Compressed State Vibration creates sound wave 6
    7. 7. Piezo Buzzer StructureTransducer (without driving circuitry) Casing Piezoceramic Element TerminalIndicator (with driving circuitry) Casing Piezoceramic Element Circuit Board Terminal 7
    8. 8. Feedback• The feedback line provides a voltage that is proportional to the strain on the main piezo element.• This voltage can be used to create a simple, self-oscillating, circuit. 8
    9. 9. Magnetic BuzzersStructure of Magnetic BuzzerNo Name of Parts1 Casing2 Vibrating Weight3 Cavity4 Vibrating Disk5 Magnet6 Pole7 Coil8 Yoke Plate9 PCB10 Transistor11 Epoxy12 Pin 9
    10. 10. Working Principle Vibrating disk Magnet Pole Coil Yoke Plate 10
    11. 11. Indicators vs. TransducersIndicators• Built-in driving circuit• Simple to design-in• Fixed frequencyTransducers• External driving circuit required• Complex to design-in• User-selected frequency 11
    12. 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 dB’s 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. 13. dB’s• dB stands for decibel.• It is not a unit, but rather a numeric scale.• Values increase exponentially, instead of linearly as in counting numbers.• Expressed in “normal” numbers, 2 dB is ten times 1 dB.• Allows for a huge range of values to be expressed in relatively little space. 13
    14. 14. Frequency Response• A perfect audio transducer would recreate every frequency without attenuation or gain. There is no perfect transducer.• Frequency response is a quantitative measurement of a device’s ability to recreate any frequency. 14
    15. 15. The Human Ear and A-Weighting Comparison of Different SPL’s• Generally, most humans can Jet engine 632 Pa 150 dB perceive frequencies from at 30 m 20–20,000 Hz. Threshold of pain 63.2 130 dB• However, the human ear is Hearing damage (possible) 20 Pa Approx. 120 dB more sensitive to some Jet at 100 m 6.32–200 Pa 110–140 db frequencies than others. Jack hammer at 1 m 2 Pa Approx. 100 dB• A-weighting places more value Traffic on a busy roadway at 2x10-1–6.32x10-1 Pa 80–90 dB on frequencies which the 10 m human ear is more sensitive to. Passenger car at 10 m 2x10-2–210-1 Pa 60–80 dB• Some CUI buzzers specify SPL Normal conversation at 1 m 2x10-3–2x10-2 Pa 40–60 dB using the A-weight system. I.E. Very calm room 2x10-4–6.32x10-4 Pa 20–30 dB dB A Auditory threshold at 1kHz 2x10-5 Pa (RMS) 0 dB 15
    16. 16. Resonant Frequency• The natural frequency a system tends to oscillate at.• Driving a system at its resonant frequency will create the largest amplitudes with the smallest input.• Buzzers are loudest when driven at their resonant frequency. 16
    17. 17. Sound Effects• A buzzer is usually used as a warning sound, i.e. car security, car reverse aid, 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. 18. Mounting Configurations Surface mount PCB mount Panel mount Vertical mount Snap-in Wire leadsWire leads w/flange 18
    19. 19. Applications Home Automotive Medical Appliances Security Industrial Office Automation 19
    20. 20. Summary• CUI Inc’s buzzers are used across a range of applications as indicators and alerts• Two main technologies are used to generate sounds: magnetic and piezoelectric• Indicators include a built-in driving circuit while transducers require and external source to create a tone• View CUI’s buzzer product offering 20
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