Piezo Buzzer

Thread Starter

chaos51

Joined Jun 18, 2011
42
Hi,

I am a bit puzzled, I am trying to amplify an audio signal, with a lm386n-1, and I am sure I got the circuit right, as it amplifys loudly through my speaker.

However putting a smaller and more convenient piezo buzzer in place of the speaker, gives me a soft signal, as if there was no amplification.

I put the piezo buzzer directly on the sourcesignal, and the loudness is the same as it is after amplification.

So what is so different in Piezo buzzer as from "normal" loudspeakers, that they seemingly ignore a amplified signal?

Thanks
DaC
 

WBahn

Joined Mar 31, 2012
29,932
Many piezo buzzers are self-contained circuits and the two wires going to them are to provide power when you want the thing to make noise.

What piezo buzzer, specifically, are you trying to use?
 

Bernard

Joined Aug 7, 2008
5,784
Big difference in impediance , speaker about 8 Ω, piezo speaker, guess about 100k Ω; might use a 8 Ω to plate transformer to match ??
 

Audioguru

Joined Dec 20, 2007
11,248
A piezo "buzzer" has a built-in oscillator.
Maybe a piezo "transducer" (speaker) is used instead.
A piezo transducer has a few high frequency resonances where it is loud but low frequencies are not produced. Frequencies between resonances are not loud.
 

takao21203

Joined Apr 28, 2012
3,702
piezo is a lot like a capacitor.
They need a discharge facility.

And they are also often used with higher voltages.

Sometimes coils are used for this purpose.

Using them with direct DC drive only, it's helpful to put a resistor in parallel, 1K or the like, this will improve output.
 

Thread Starter

chaos51

Joined Jun 18, 2011
42
Many piezo buzzers are self-contained circuits and the two wires going to them are to provide power when you want the thing to make noise.

What piezo buzzer, specifically, are you trying to use?
I am not sure really. I bought it locally, labeled as "Piezo Buzzer", with no more details then that. It's a black cylyndrical shape the size of a button, but thicker, and has the markings ZO and a tiny logo saying "M".
 

Thread Starter

chaos51

Joined Jun 18, 2011
42
A piezo "buzzer" has a built-in oscillator.
Maybe a piezo "transducer" (speaker) is used instead.
A piezo transducer has a few high frequency resonances where it is loud but low frequencies are not produced. Frequencies between resonances are not loud.
Thanks... That was helpfull.. Indeed the higher frequencies are pretty hearable, the low once are not. And yes you are right, it probably is a transducer and not a buzzer.
 
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