piezo buzzer with a sorry-ass data sheet

Thread Starter

mikewax

Joined Apr 11, 2016
118
Hello everyone,
maybe some of you analog experts can help me. i got a data sheet for a (www.cui.com/product/resource/cmt-8530s-smt.pdf) MAGNETIC BUZZER TRANSDUCER, it's just a pz disc and a coil housed in a resonant casing. WTF? LCOIL= ?, CDISC = ?.
It says that the current consumption is 90 mA. that's with a square wave, 50% duty cycle, at 2730Hz. and a voltage of 0 - 3.6
the RCOIL = 16ohms.
but i have to drive it at different voltages and and duty cycles. how to calculate the current for arbitrary V and duty cycle?
i'm assuming it's a standard parallel L and C circuit.
is it possible with so little information?
sheet.png
 

Sensacell

Joined Jun 19, 2012
2,449
Nothing in the data sheet says anything about piezo anything, it's an electromagnetic device.

Think of it as a speaker with an acoustically resonant housing.
 

Thread Starter

mikewax

Joined Apr 11, 2016
118
I don't see any polarisation indication on the device or in the datasheet.
holy crap it IS polarized. there's a teeeeny little "+" on the case. for some reason, the flyback doide did not register in my brain. i assumed it was a pz because it has an output of 90 dB. except.......... damn it's not dB it's dBA. what is dBA?
and i don't know what these specs mean. V = 3.6, I = 90mA, R = 13ohms. these #s obviously don't add up. is there a way to find L?
sheet2.png
 
Last edited:

BobaMosfet

Joined Jul 1, 2009
829
Datasheet is fine. Perhaps you're wanting to use the buzzer in a way other than which it was designed for?

Per the datasheet, it expects a 3-5VDC @ 50% PWM duty cycle input at the expected frequency. You can see what other frequencies deliver, but it's really meant to input at a given (rated) frequency of 2730 in order to generate a specific tone at about 90dBA. 25dBA is equivalent to a person whispering, as I recall.
 

Thread Starter

mikewax

Joined Apr 11, 2016
118
Per the datasheet, it expects a 3-5VDC @ 50% PWM duty cycle input at the expected frequency. You can see what other frequencies deliver, but it's really meant to input at a given (rated) frequency of 2730 in order to generate a specific tone at about 90dBA. 25dBA is equivalent to a person whispering, as I recall.
yeah it's becoming clear now. i misread the data sheet to begin with. but it still seems odd to me that they do not have any number for inductance, or at least an IV curve.
thanx guys for your answers :)
 

Audioguru

Joined Dec 20, 2007
11,251
4kHz is pretty high and old people without hearing aids (or young people deafened by rock music) might barely hear them.
A distance of only 10cm is almost wearing them on your ears. With any distance then their sound will be faint. They are too small to do it. Why not use a piezo beeper that is much louder and uses much less current.
 

Thread Starter

mikewax

Joined Apr 11, 2016
118
4kHz is pretty high and old people without hearing aids (or young people deafened by rock music) might barely hear them.
A distance of only 10cm is almost wearing them on your ears. With any distance then their sound will be faint. They are too small to do it. Why not use a piezo beeper that is much louder and uses much less current.
because the device i'm making is really small. 40 x 25 x 6mm. a pz requires a choke to drive it, and i can't find a choke that is small enough to fit. it would have to have D <= 6mm.
 

Dodgydave

Joined Jun 22, 2012
8,466
That's a 4Khz buzzer, you're better using a Frequency of 2.7Khz to 3.7Khz for maximum hearing sensitivity, as that's what human hearing is tuned to.

Most burglar alarms and sirens are tuned to this band for maximum volume .
 
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