Buzzers and sound elements used in electronic devices

Publish date 2022-02-20
We are all very familiar with various sound signals produced by our devices. Whether it's the ringing of a cell phone, the microwave oven shutdown bell, or the much hated morning alarm clock, there are endless examples. Some of you may be wondering what components are responsible for generating these sounds. How do they work? What is the essence behind them? And finally, what type of sound component should I choose for my project? If you are interested in the answers to these questions, you have come to the right place. In today's article we would like to introduce you to the topic of sound components used in electronics. We will present in detail the characteristics of each type of these components, as well as discuss examples of their use.

Why are sound signals so important?

On the surface, it may seem that beeps and sounds produced by devices are unnecessary and sometimes even annoying. However, this is not the case – audible signals have important functions, both informative and warning. One of the main tasks of buzzers is to get the user's attention or inform them of some important event. Using a sound signal for this purpose is the best solution because it is heard from a distance – the person does not have to be focused on the device to notice it. Sound effects are also inherent in some types of interfaces, especially those without physical buttons – touchscreen displays are one example. With sounds, we can interact with more of the user's senses. This way, we can increase the intuitiveness of use and enhance user experience.

What types of sound elements do we have to choose from?

Sound sources used in electronics can be divided by their method of operation, power supply requirements, the volume and frequency of the sound they produce, as well as their size and shape. Below is a summary of the most common types of sound components to help you choose the right one.

Electromagnetic buzzers

These components are among the simplest of sound transducers. Although they come in various forms and shapes, their principle of operation is the same. The main element of their construction is a mechanical system consisting of a coil and a permanent magnet. When alternating current is applied to the coil, it generates vibrations that are heard as sound. In the case of typical electromagnetic buzzers used in electronics, the frequency of the generated tone ranges from a few hundred Hz to a few kHz.  Elements of this type typically have a small, cylindrical or rectangular housing designed for PCB mounting. Buzzers designed for panel or enclosure mounting are also available.

Buzzers with generators – how do they work?

The simplest in implementation sound signaling device is a buzzer with its own signal generator. It is enough to supply voltage and we get a sound – we don't have to worry about anything else. However, we do not have control over the sound pitch of such a buzzer. It is able to generate a single tone of a certain frequency, which for most simple applications is quite enough. For example, a short buzzer sound can accompany the user touching a button on a touch screen. If we want to communicate some specific message to the user, we can use a sequence of tones. Let's look at an example – the GMD-12065YB generator buzzer we offer is one of the most widely-used types. It has a cylindrical housing with through-hole mounting and is powered by 5VDC. Despite low current consumption, which is only 30mA, it is able to generate sound with a volume of 85dB. This makes it easy to hear even in a noisy environment. A wide operating temperature range makes it a good choice for more demanding applications, while a protective sticker protects the sensitive membrane during the assembly and PCB cleaning. In the table below we present the most important parameters of GMD-12065YB buzzer:
Symbol GMD-12065YB
Type Electromagnetic buzzer with generator
Dimensions ⌀12.0mm × 6.5mm
Rated voltage 5V DC
Rated current 30mA
Sound frequency 2.7kHz
Sound pressure level (SPL) 85dB
Working temperature -20 ÷ 70 ° C
Storage temperature -30 ÷ 80 ° C

Buzzers without generator

As the name suggests, these components are devoid of a signal generator – their input pins are connected directly to the voice coil windings. Thanks to that, we have full control over the sound of the buzzer – we can get the tone of any waveform and frequency. However, it happens at the cost of a slight increase in complexity of the circuit, whose task is to generate an appropriate signal. For this purpose, most often a microcontroller with a dedicated digital-to-analog converter (DAC) is used, less often oscillators or other types of analog circuits. The ability to generate a modulated beep, multi-tone or melody greatly expands the range of uses for a simple buzzer. For example, it can be used in a doorbell or a telephone earpiece. However, one should keep in mind the range of processed frequencies, which in this case is quite limited. The best audible tones will be close to the natural resonant frequency of the buzzer, while others may be distorted or too quiet. An interesting example of a buzzer without a generator is the GSC-9032RB offered by us. It features a resonance frequency of 2700Hz and SMD mounting. However, the most noticeable thing is its characteristic shape – its outlet is placed on the side of the housing. This allows to easily direct the sound in the desired direction. Also noteworthy is the operating voltage, which is only 3V – it can be easily integrated into the low-voltage logic circuitry. Full specifications are presented in the table below:
Symbol GSC-9032RB
Type Electromagnetic buzzer without generator
Dimensions ⌀9.0mm × 3.2mm
Rated voltage 3V DC
Rated current 80mA
Resonant frequency 2.7kHz
Sound pressure level (SPL) 85dB
Working temperature -20 ÷ 80 ° C

Piezoelectric transducers

Transducers of this type are usually in the form of a metal disk covered with a thin layer of piezoelectric material. Under the influence of a current this material deforms, causing the plate to bend and thus produce sound. In order to obtain a sufficient intensity of sound, the transducer must be mounted in a specially shaped chamber or housing cut-out. Piezoelectric buzzers typically operate at a slightly higher voltage than their electromagnetic counterparts. The sound frequencies, which they are able to generate, are also higher – they even reach ultrasounds. Similarly as in case of other types of buzzers, we have available versions with and without a built-in generator. Piezoelectric transducers are primarily used as sound sources in devices such as digital watches, stopwatches and alarm clocks. They can also be found in alarm sirens and ultrasonic proximity sensors. Due to their frequency range, they can also be found in some multi-way speaker assemblies, where they act as tweeters.

Speech and music playback

Have you ever had a self-service cash register in a store speak to you? Speech reproduction is one of the more sophisticated tasks for which sound components are used. It should not be surprising that ordinary buzzers are not sufficient for this task. However, wide-range loudspeakers, which have a much greater frequency range, are ideal.   Most of the sounds responsible for the intelligibility of human speech are contained in the frequency range between 500Hz and 4kHz. However, to make the speech sound natural and clear, it is necessary to cover a much wider range. The target frequency span is about 100Hz – 17kHz, so it covers most of the human hearing range. A balanced frequency response across the entire frequency range is also very important. It allows for a clear and undistorted sound. If the quality of sound is particularly important to us, it is advisable to use a resonance chamber. It is a specially constructed speaker enclosure, allowing to increase the efficiency and improve reproduction of low tones. The use of a full-range speaker brings numerous advantages. The ability to play music and enable voice assistant integration are just some of them. In addition, thanks to high quality and natural sound effects we are able to make a special impression on the user. However, driving a speaker can be quite challenging – most often a dedicated audio amplifier circuit is required for this purpose. Designing loudspeaker enclosures also requires some knowledge in the field of acoustic engineering.

Rely on our specialists!

InterElcom has many years of experience in the distribution of electronic components as well as designing equipment for various industries. By carrying out your project with us, you can be sure that we will choose the best components and technologies for you. Our qualified staff will also provide you with professional advice and support throughout the period of the cooperation. We encourage you to contact us and obtain a free quote. If you are interested in our wide offer of electronic components we invite you to take a look at our product catalog – you will surely find what you need there.