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Author Topic: How to get the highest quality sound from a port pin driven buzzer?  (Read 314 times)

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Offline georgd

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I'm developing a device with simple port driven buzzer. The role of buzzer is a simple signalling without need to reproduce music or speak.
The question could I improve the sound quality if I drive it with trapezoid instead of square wave?
Under quality I meant sound more music like sound instead of simple buzzer like.
Even drive it with two port pins in bridge like circuit?

Thanks in advance,
Georg
 

Online hamster_nz

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Re: How to get the highest quality sound from a port pin driven buzzer?
« Reply #1 on: August 16, 2017, 03:05:14 PM »
If you lack the gear yourself, I can hook a buzzer up to an Arbitrary Wave Generator and test.

It it just standard microcontroller pin levels?
 

Offline ealex

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Re: How to get the highest quality sound from a port pin driven buzzer?
« Reply #2 on: August 16, 2017, 06:05:18 PM »
if you're driving it with TTL levels you'll have all square-wave harmonics in the output.

look here for some frequency response plots and drive ideas : http://www.murata.com/~/media/webrenewal/support/library/catalog/products/sound/p37e.ashx

by tying the buzzer between 2 pins you can gen a louder sound from the same speaker - something like full versus half wave

maybe adding a series resistor will make a low-pass filter with the buzzer's capacitance - and cut some of the high frequency content
(i might try that on one of my projects as well)
 

Offline nfmax

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Re: How to get the highest quality sound from a port pin driven buzzer?
« Reply #3 on: August 16, 2017, 06:16:22 PM »
Don't forget you can also put the output pin into tri-state for part of the cycle. This might let the buzzer ring at its natural resonant frequency for part of the time. Perhaps driving it with a short pulse at a sub harmonic of its resonance and leaving it tri-state the rest of the time will give a better tone. But anything you do will be highly dependent on the actual type of buzzer used (and variation between different buzzers of the same type). Experiment!
 

Online Rerouter

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Re: How to get the highest quality sound from a port pin driven buzzer?
« Reply #4 on: August 16, 2017, 06:19:08 PM »
As a piezo buzzer is mainly capacitive , you can add a series inductor to it to shape the pulse closer to a resonant sine,

The balance comes from the role of the buzzer, anything that "warbles" between 2-4Khz is extremely hard for us humans to ignore,

If you just want to notify someone, then pure tone "pip"s tend to be the least offensive. around 2Khz,

If you want someone to be unable to ignore it, square wave, that varies about 200Hz at 4Khz. (vary the pulse width) about 1 second on, 2 seconds off.
 


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