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Making piezo buzzer to emit heat

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Nicolaii

New Member
Hi,
I my project I need to make piezo buzzer emit heat. I use transistor and DC to DC voltage converter (3.3 to 10V.). When i make square wave signal with signal generator piezo uses only ~7V to start heating. Sadly, when i am doing the same on microcontroller it just does not heat. Plus I cant get high amplitude of noise.
When i connect piezo, there is a voltage dropout on scheme. Could it be problem of impedance? My piezo is 14uF so I tried ~100uH inductor in parallel but it does not help. Worse, it emits heat by itself ( Not piezo but inductor and that is opposity of my need).

Is there some scheme that could help me to get out of this situation? Maybe I just forgot something important?
 

spec

Well-Known Member
Most Helpful Member
Hi Nicolaii,

Welcome to ETO. Can you put were you are at, next to 'Location' on your user page so that it displays in the box at the left of your posts. That helps us to give better answers to questions.:)

Sounds like you have a fairly simple problem but we would need a bit more information to be able to analyze what is going on. If you could post a schematic of your set up, I'm sure one of us can help out. A hand sketch will do.:)

spec
 

audioguru

Well-Known Member
Most Helpful Member
A piezo "buzzer" has a built-in transistor oscillator. Maybe you have a piezo transducer? A transducer is like a little speaker.
It measures like a capacitor so it makes no heat unless it is operating at a voltage higher than its maximum allowed voltage rating.

The capacitance of your piezo transducer is 1000 times higher than the large ones I have found. Why?
 

Nicolaii

New Member
I have beent to abstarct i see :) Yes, I have transducer. I am trying to make buzzer. So strong, that could emit heat. I know that there are plenty o them made for medical use, but i cant find out how.
Firsly, what is that transistor oscillator? Is it something like in my scheme? It does not work. Piezo only get ~0.3V while supply give 10V.
Secondly, sorry I just made a mistake. It is 14 nF not uF.
Thanks for fast replies!
 

chemelec

Well-Known Member
Where in the Medical Field is a Piezo Transduce (Speaker) used to Generate HEAT?
I have never heard of that.
I Don't see How, That Sounds really Strange.
 

alec_t

Well-Known Member
Most Helpful Member
You are unlikely to get the piezo to self-heat significantly, but concentrated high-energy ultrasound can be used for heat generation in a test material.
 

chemelec

Well-Known Member
My Impression from what I have read is:
High Intensity Ultrasonic Sound from a Piezo Device can be Focused to generate Heat on Human or Animal Tissue.
Not Actually heating the Piezo Element.
 

tcmtech

Banned
Most Helpful Member
If you need heat use a common resistor. It's way simpler and easier to work with. :rolleyes:

I don't follow the concept to trying to make heat with a sound emitting device. It makes no sense whatsoever. :oops:
 

AnalogKid

Well-Known Member
Most Helpful Member
My Impression from what I have read is:
High Intensity Ultrasonic Sound from a Piezo Device can be Focused to generate Heat on Human or Animal Tissue.
Not Actually heating the Piezo Element.
Correct. I've had it, and it can be a weird experience feeling heat inside a muscle but not on the surface.

ak
 

chemelec

Well-Known Member
On generator it only needs 6-8 V to heat by itself
I Don't Believe that is Possible.
It is just an AUDIO Device.

If that were the case, than Piezo Tweeters in Speaker systems would have REAL PROBLEMS, some Getting more than 20 VAC.
 

dr pepper

Well-Known Member
Most Helpful Member
My ultrasonic cleaning tank piezo gets warm, without solution it'd proabbly melt, but I think thats a parasitic effect.
If you upped the voltage enough I spose heat would be generated, life of the buzzer would go down too.
The circuit in post #4 can be made to drive the piezo as hard as you like, the inductor will apply a voltage to the piezo to equal current through it at switch off equal to inductor charging current, the tranny has to be capable of standing off this voltage which can be 100's of volts.
 

AnalogKid

Well-Known Member
Most Helpful Member
I Don't Believe that is Possible.
It is just an AUDIO Device.
If that were the case, than Piezo Tweeters in Speaker systems would have REAL PROBLEMS, some Getting more than 20 VAC.
Depends on the thermal mass of the device relative to the electrical power being converted/dissipated.

ak
 

audioguru

Well-Known Member
Most Helpful Member
A piezo is a capacitor that does not conduct. The material flexes back and forth when fed AC that might cause some warming.
 
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