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piezo transducer failure mode on overvoltage.

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piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
List,

I have an application using a audio piezo-transducer and it is rated at
5V; we want to run it at 9V; because it is louder.

I am wondering what the failure mode would be for a device like this.

In the application, it runs for short duration (300 mS) and
infrequently. The average maximum cycle time is probably something
roughly like every 5 minutes (or more) when in use, but it can repeat as
frequently as ~1 second intervals as part of a "cycle." But each "cycle"
consists of only two beeps.

I have run it at 9V as a test, but am trying to get a handle on what
could be expected longevity-wise at this elevated voltage.

I have contacted the factory, but have received no response so far.

I realize it's out of spec.    :-)

Is it power dissipation? Is it actual voltage?

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Re: piezo transducer failure mode on overvoltage.

Wouter van Ooijen
> Is it power dissipation? Is it actual voltage?

I'm no expert, but I would guess the failure mechanism to be breaking
due to instantaneous power. So a low duty cycle will not help.

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Re: piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
That makes sense; sort of like repeatedly hitting a ceramic plate with a
small hammer........?

Mark

Wouter van Ooijen wrote:
>> Is it power dissipation? Is it actual voltage?
>>    
>
> I'm no expert, but I would guess the failure mechanism to be breaking
> due to instantaneous power. So a low duty cycle will not help.
>
>  
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Re: piezo transducer failure mode on overvoltage.

Wouter van Ooijen
Mark E. Skeels wrote:
> That makes sense; sort of like repeatedly hitting a ceramic plate with a
> small hammer........?

I think that is way outside the specs ;)


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RE: piezo transducer failure mode on overvoltage.

Michael Rigby-Jones-2
In reply to this post by Mark E. Skeels-3


> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On
Behalf
> Of Mark E. Skeels
> Sent: 23 February 2010 16:38
> To: Microcontroller discussion list - Public.
> Subject: [EE] piezo transducer failure mode on overvoltage.
>
> List,
>
> I have an application using a audio piezo-transducer and it is rated
at
> 5V; we want to run it at 9V; because it is louder.
>
> I am wondering what the failure mode would be for a device like this.

Is this a bare Piezo element, or a complete buzzer including the driver
circuit?  i.e. do you just supply a DC voltage to make it buzz or do you
drive it with an AC waveform?

Mike

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Re: piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
It's a two-terminal device; I am driving it with a 1500 Hz square wave.

Mark


Michael Rigby-Jones wrote:

>  
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]] On
>>    
> Behalf
>  
>> Of Mark E. Skeels
>> Sent: 23 February 2010 16:38
>> To: Microcontroller discussion list - Public.
>> Subject: [EE] piezo transducer failure mode on overvoltage.
>>
>> List,
>>
>> I have an application using a audio piezo-transducer and it is rated
>>    
> at
>  
>> 5V; we want to run it at 9V; because it is louder.
>>
>> I am wondering what the failure mode would be for a device like this.
>>    
>
> Is this a bare Piezo element, or a complete buzzer including the driver
> circuit?  i.e. do you just supply a DC voltage to make it buzz or do you
> drive it with an AC waveform?
>
> Mike
>
> =======================================================================
> This e-mail is intended for the person it is addressed to only. The
> information contained in it may be confidential and/or protected by
> law. If you are not the intended recipient of this message, you must
> not make any use of this information, or copy or show it to any
> person. Please contact us immediately to tell us that you have
> received this e-mail, and return the original to us. Any use,
> forwarding, printing or copying of this message is strictly prohibited.
> No part of this message can be considered a request for goods or
> services.
> =======================================================================
>
>  
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Re: piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
In reply to this post by Wouter van Ooijen
Aah.

An attempt to make me think about and realize the stupidity of my design
without making me feel bad.....

:-)

Mark

Wouter van Ooijen wrote:

> Mark E. Skeels wrote:
>  
>> That makes sense; sort of like repeatedly hitting a ceramic plate with a
>> small hammer........?
>>    
>
> I think that is way outside the specs ;)
>
>
>  
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ivp
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Re: piezo transducer failure mode on overvoltage.

ivp
In reply to this post by Mark E. Skeels-3
> It's a two-terminal device; I am driving it with a 1500 Hz square wave

Do you have any other components connected to it ? A small inductor
in parallel with the piezo, for resonance, will increase loudness. So will
a resistor, to a lesser extent. For example the beeper in a watch is often
a disc piezo + inductor. Without R or L the sound is quite weak

Attached are a couple of circuits I use (although 50V is pushing it a
little)

wbr

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piezo_drive.gif (1K) Download Attachment
piezo-50V.gif (2K) Download Attachment
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Re: piezo transducer failure mode on overvoltage.

Vitaliy-14
ivp wrote:
> Attached are a couple of circuits I use (although 50V is pushing it a
> little)

OT question: which CAD program did you use to produce the schematics?

Vitaliy
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Re: piezo transducer failure mode on overvoltage.

ivp
> OT question: which CAD program did you use to produce the schematics?

Ye olde cut 'n' paste

http://home.clear.net.nz/pages/joecolquitt/circuit_symbols.gif

Something I started with ex-lister Ken Webster many years ago

I should put it up on piclist.com too

wbr
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Re: piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
In reply to this post by ivp
No, I don't and I'll look into your suggestion; thanks!

Mark


ivp wrote:

>> It's a two-terminal device; I am driving it with a 1500 Hz square wave
>
> Do you have any other components connected to it ? A small inductor
> in parallel with the piezo, for resonance, will increase loudness. So
> will
> a resistor, to a lesser extent. For example the beeper in a watch is
> often
> a disc piezo + inductor. Without R or L the sound is quite weak
>
> Attached are a couple of circuits I use (although 50V is pushing it a
> little)
>
> wbr
>
> ------------------------------------------------------------------------
>
>
> ------------------------------------------------------------------------
>
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Re: piezo transducer failure mode on overvoltage.

William "Chops" Westfield
In reply to this post by ivp

>> It's a two-terminal device

Are you sure about the rated max voltage?  Piezos tend to like higher  
voltages, and (for example) most of the bare piezos I see at digikey  
that have a 5V rated voltage also have an "operating voltage range"  
that goes much higher (typically 1-25Vp-p)...

BillW

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Re: piezo transducer failure mode on overvoltage.

Mark E. Skeels-3
Well, the data sheet does not specify anything but "Rated Voltage" but
it may very well be as you say.

If so, that would be very nice.

As of now, I have not yet heard anything from the manufacturer.


Mark

William "Chops" Westfield wrote:

>>> It's a two-terminal device
>>>      
>
> Are you sure about the rated max voltage?  Piezos tend to like higher  
> voltages, and (for example) most of the bare piezos I see at digikey  
> that have a 5V rated voltage also have an "operating voltage range"  
> that goes much higher (typically 1-25Vp-p)...
>
> BillW
>
>  
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Re: piezo transducer failure mode on overvoltage.

ivp

> Well, the data sheet does not specify anything but "Rated Voltage" but
> it may very well be as you say.

For piezo discs that I'm familiar with, when you add an inductor a tank
circuit is created, as the piezo is a capacitor. The voltage spikes
generated
are more than 5V, so I'm not sure what "Rated Voltage" is applying to.
Self-contained 5V beepers will have a multiplier inside to make a higher
V+ for the element (some are also quite magnetic, which indicates some
ferrous or ferrite enhancement), so *they* should probably not be over-
driven

wbr

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Re: piezo transducer failure mode on overvoltage.

Xiaofan Chen
In reply to this post by ivp
On Wed, Feb 24, 2010 at 4:40 AM, ivp <[hidden email]> wrote:
>> OT question: which CAD program did you use to produce the schematics?
>
> Ye olde cut 'n' paste
>
> http://home.clear.net.nz/pages/joecolquitt/circuit_symbols.gif
>
> Something I started with ex-lister Ken Webster many years ago
>
> I should put it up on piclist.com too

Nice one. Last time a colleague (from India) made a lot of
similar things, all using Paint. He could even use Paint to
draw very nice pictures like some Hindu God. Amazing.


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Re: piezo transducer failure mode on overvoltage.

Peter van Hoof-2
In reply to this post by Mark E. Skeels-3
There is a very informative design guide written by Murata here
http://www.murata.com/catalog/p15e6.pdf

The easy way to get more volume out of a piezo   (if you just need a tone)
without driving  it harder is by driving it at the resonance frequency. (or a harmonic of it)

Peter van Hoof



----- Original Message ----
> From: Mark E. Skeels <[hidden email]>
> To: Microcontroller discussion list - Public. <[hidden email]>
> Sent: Tue, February 23, 2010 11:38:06 AM
> Subject: [EE] piezo transducer failure mode on overvoltage.
>
> List,

I have an application using a audio piezo-transducer and it is
> rated at
5V; we want to run it at 9V; because it is louder.

I am
> wondering what the failure mode would be for a device like this.

In the
> application, it runs for short duration (300 mS) and
infrequently. The
> average maximum cycle time is probably something
roughly like every 5
> minutes (or more) when in use, but it can repeat as
frequently as ~1 second
> intervals as part of a "cycle." But each "cycle"
consists of only two
> beeps.

I have run it at 9V as a test, but am trying to get a handle on
> what
could be expected longevity-wise at this elevated voltage.

I
> have contacted the factory, but have received no response so far.

I
> realize it's out of spec.    :-)

Is it power dissipation? Is it
> actual voltage?

--
Mark
--
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> & list archive
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> at
http://mailman.mit.edu/mailman/listinfo/piclist


     

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copyright violation .... was: piezo transducer failure mode on overvoltage.

YES NOPE9
In reply to this post by ivp
I see that the page is copyrighted.... If I use the symbols , will I  
be shot ?
Gus


> On Feb 23, 2010, at 1:40 PM, ivp wrote:
>
>> OT question: which CAD program did you use to produce the schematics?
>
> Ye olde cut 'n' paste
>
> http://home.clear.net.nz/pages/joecolquitt/circuit_symbols.gif
>
> Something I started with ex-lister Ken Webster many years ago
>
> I should put it up on piclist.com too
>
> wbr


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Re: copyright violation .... was: piezo transducer failure mode onovervoltage.

ivp
>I see that the page is copyrighted.... If I use the symbols , will I  
> be shot ?

Could shoot you anyway. Can I have a hands-up for a squad ?

The copyright notice is just a useable part of the graphic. But you
knew that.....

wbr
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