Go Down

Topic: Piezo Buzzer - how to generate dynamic tone and constant tone? (Read 62 times) previous topic - next topic

EricExperiment

I'm looking at the Grove Piezo buzzer below:

https://www.seeedstudio.com/Grove-Buzzer-p-768.html

I see the Seed design has a transistor (Q1) and a resistor (R1).  The buzzer description saids:


Quote
1)  buzzer emits a tone when SIG is high
2)  "Alternatively it can be connected to an analog pulse-width modulation output to generate various tones and effects"
How is that possible with just a transistor and resistor?  I thought Piezo buzzers need some kind of frequency input in order to make a sound.  How does the Grove piezo generate sound with just a constant high signal?

Also, when it saids "analog pulse-width modulation", is that a typo?  Is it really just digital PWM, where the frequency changes ("analog" frequency)?  Or is it a thing to use the analog pings to do PWM?




DVDdoug

A buzzer  has a built-in sound generating circuit and it operates from DC.  

A transducer  or speaker  is passive and it reproduces the signal fed-into it.

Some people and some "cheap" sellers use the wrong descriptions.

Generally, you can drive a piezo transducer directly from the Arduino.   A buzzer usually requires more current so it might need a transistor or MOSFET driver.

Quote
Also, when it saids "analog pulse-width modulation", is that a typo?
Probably not very-well written.    You'd be modulating whatever tone is reproduced by the buzzer.   That could be "interesting" depending on what you're want, but it's not going to play a melody.

wolframore

If that is an active buzzer on there the electronics are located inside the speaker device.  Like Doug says, the transistor is there only for switching.

I wonder if they mean PCM by their analog statement.  I might be chinese-english...
Bad boys rate our young girls but Violet goes willingly :)
- this is a mnemonic from BEC

Go Up