![]() ![]() I suspect the "mistake" is actually a case of your instructor disagreeing with whoever wrote the course material rather than a real mistake but without more detail it is hard to be sure.Įxists probability that you will got somewhere buzzer device with internal frequency generating circuit.īut most probably, you will got device, which just transforms electricity to sound waves.įor such devices, the most important features - are their resistance and loudness (when have comparable size/weight), and unfortunately, exists extreme difference of piezo vs electromagnetic speakers in these.įor resistance: most small electromagnetic speakers used in computers have resistance approximately 8 Ohm. Whether to class piezo sounders as "buzzers", "speakers" or neither is somewhat a matter of semantics. However they are not designed to reproduce arbitrary audio with anything like reasonable accuracy. ![]() That allows multiple tones for different types of alert and even allows playing crude music. They are driven with an audio-frequency waveform, typically a square wave. These are something of a half-way house between the traditional buzzers and speakers. So nowadays instead of a traditional mechanical buzzer we often use "piezo sounders". The relative cost of electronics in general and micro controllers in particular has dropped compared to the cost of electromechanics. However in more recent years the world has moved on. It would typically be supplied with DC and the oscillations would have been produced by an electromechanical process inside the buzzer.Ī speaker was/is a device used to reproduce sound from an electric waveform with the sound coming out being at least a passable analogue of the signal going in. Traditionally it would have been an electromechanical device. Remember, the easiest way to lower power consumption is to turn the thing off.Traditionally a buzzer was a device designed to make noise. Even at 1 Hz beeps, the thermal overload protection in your power supply shouldn't kick in during brief applications of power. If it can be quieter, then drive it at lower voltage (or apply an ultrasonic PWM to the driver).Īs an alternative, consider beeping the sounder intermitently rather than providing a continuous tone. You said 'buzzer', so you are probably able to tolerate the different sound produced by driving it with a 1000 Hz rectangular wave at 10% duty cycle. The CUI datasheet says:Ĭurrent consumption | at rated voltage, 4,000 Hz square wave, ½ duty | 110 mAĬlearly, this will be less if you drive it at a lower voltage, it will likely be less if you drive it at a lower frequency, and it will be less if you drive it at a lower duty cycle. They usually require between 70 and 110 mA, but consider the sound pressure levels that they generate and the drive method. Other parts like this CUI buzzer are available in similar packages. That part has the same form factor (visually) as their other NFT parts, it's tiny at about 5mm by 5mm by 2mm, but there's no datasheet and it's not available through the ordinary distributors. I have a Star Micronics NFT-03A electromagnetic sounder on my EK-LM3S6965 board. For every part that I've worked with (just one) and every datasheet I looked up (three), the required currents were for operation at rated voltages. If the magnetic sounder requires too much power, you will simply need to provide it with less power. If those are still not small enough, well, the cell phone and earbud industries have spent millions trying to make really small speakers and this is the best they've done. If 9mm piezo elements are too large, you're basically stuck with a magnetic sounder. ![]()
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