9/3/2023 0 Comments Piezo sounder with cover![]() ![]() 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. A FET can be used instead of the transistor.Ĭase 2: Driven directly from a microcomputer.Traditionally a buzzer was a device designed to make noise.Also, in order to protect the transistor itself, consider connecting a Zener diode in parallel with the piezoelectric sound component and Rp if necessary. The transistor functions as a buffer for protecting the IC from back electromotive force generated by the piezoelectric sound component.680Ω to 1kΩ would be preferable.)Īlso, if necessary, use Rs for volume adjustment. Rp in the diagram is necessary for discharging the charge accumulated in the piezoelectric sound component, so be sure to use it.Please refer to the following supplementary notes regarding the components shown in the circuit diagram. Consequently, this drive method is widely used in cases where a power supply voltage that is higher than the drive voltage for the microcomputer can be obtained. The higher the value of the voltage applied to V, the higher becomes the sound pressure of the piezoelectric sound component. ![]()
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