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Author Topic: Heat conversion by using piezzo effect  (Read 34307 times)

andreas_varesi

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Heat conversion by using piezzo effect
« on: April 12, 2005, 12:59:59 AM »
I found a German patent from Michael Jennsen DE 199 42 739 A1. He uses piezzo ceramic rings with a diameter less than 0,1mm and a membrane out of noble metal. Driven by ambient temperature the gas pressure is quickly changing at the small membrane. A rectifier is used to transform the chaotic alternating current into usable direct current. At this point I fear that the voltage of the small piezzo elements is to low to overcome the threshold voltage of a normal rectifier. Has any one experience with this invention?

Thanks in advance

Andreas

betajim

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Re: Heat conversion by using piezzo effect
« Reply #1 on: April 12, 2005, 03:16:51 AM »
As long the voltage generated by the piezo-electric element is greater than 0.6 volts the
rectifier will conduct current. Here is a neat trick that I use to demonstrate the piezo-electric
effect: take a piezo-electric buzzer element (the kind that are round brass disks) and connect
a LED to the two leads of the element. When the piezo disk is tapped (I use the eraser end
of a pencil) the LED will flash.

Take care.

Charlie Brown ARN

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Re: Heat conversion by using piezzo effect
« Reply #2 on: April 12, 2005, 06:15:23 AM »
I imagined using nanometer scale speaker coils and magnetic slugs or pizeoelectric elements feeding bridge rectifiers to make a strong challenge to? 2LT, the widely accepted law leading to the Grey Death of the Universe, then I pared down the design to the rectifiers. To continue the persuasion, we need to optimize the geometry of the conceptual piezoelectric device to deliver a high voltage under Brownian impacts. One approach, imaginary parts costing nothing, is to use transformers. The pizeoelectric device / transformer (Brownian, mrechanical) can be replaced by a high value resistor (Johnson, electronic).? ?

Aloha, Charlie
« Last Edit: April 12, 2005, 06:36:27 AM by Charlie Brown ARN »

Charlie Brown ARN

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Re: Heat conversion by using piezzo effect
« Reply #3 on: April 12, 2005, 06:58:59 AM »
Another transducer is the elctret microphone. Electrets are permenently electrostatically polarized materials.

Going in a new direction, imagine nanoscale pillars of polarized electret material inside a diode bridging the junction. Perhaps that would bias a diode for small signal work. This has been in my idea closet for years. Thanks for letting me be comfortable enough to share it.

Aloha, Charlie

andreas_varesi

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Re: Heat conversion by using piezzo effect
« Reply #4 on: April 12, 2005, 04:58:26 PM »
Hi Charlie,

the idea using an electret for bridging the threshold voltage of a diode is great. May I take the liberty of awarding you my private Nobel prize  ;D
But there is already the next question, do you have any idea whether it is possible to miniaturize an electret down to some nanometers by retaining a voltage of about 0,5V?  :'(

Regards
Andreas

TechStuf

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Re: Heat conversion by using piezzo effect
« Reply #5 on: April 12, 2005, 08:01:52 PM »
Interesting.....supposedly the Kowsky-Frost discovery was made while studying the PE effect....using, I believe, microphone piezos.

http://www.keelynet.com/gravity/KFrost.htm

http://www.main.org/polycosmos/gravhack/gravity.htm

http://www.rense.com/general54/babalc.htm

I find it interesting the Quartz and Gold are almost always found together in nature.


Peace,

TS out

Charlie Brown ARN

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Strength of electret charge
« Reply #6 on: April 13, 2005, 01:48:56 AM »
I slogged through google to get an idea of electret voltage and got 1/10 V / micrometer. This is not a solid number. Only a little boosting in the lowering the barrier voltage is possible because the increased conductivity of the junction reduces the effect of the electret. Electret embedding of the opposite polarity may be useful in thernovoltaic cells to help pull the electron / hole pairs apart and reduce their premature recombining .

Aloha, Charlie
« Last Edit: April 13, 2005, 02:12:08 AM by Charlie Brown ARN »

swankpower

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Re: Heat conversion by using piezzo effect
« Reply #7 on: April 25, 2005, 09:16:47 PM »
yes this idea was also in my "idea closet" for years... I thought of some ways to use piezos as diaphragms to make the motion less chaotic, so that it pulses many of these micro piezos at once...

my e-mail address is: a m m e n a r d @ u h . e d u
This has been my think hole for this past semester, and I am anxious to hear some more of the ideas you have.

Andrew Menard

Kysmett

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Re: Heat conversion by using piezzo effect
« Reply #8 on: April 25, 2005, 11:23:51 PM »
Even if It gives only .1 V, that is a 33% reduction in GaAs Diodes, bringing the threshold voltage down to .2V if I am not mistaken.  Not neseccarily something to be abandoned.

Charlie Brown ARN

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Re: Heat conversion by using piezzo effect
« Reply #9 on: April 26, 2005, 08:46:45 AM »
The pillars can be longer, first coated with an insulator, then a conductive sleeve folded back and covered with another insulator to give a higher voltage at the gap filled with the semiconductor. Maybe the structure is so large that one complex pillar surrounded by annular semiconductor would be used. This is ugly but perhaps interesting. 

Maybe deep oppositely charged doping where trapped ions would polarize the lattice behind the active dopants would do the same thing if the mobile charge carrier partners involved can be induced to work in a desirable way. 

Can advanced devices be based on InSb?

Aloha, Charlie

Kysmett

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Re: Heat conversion by using piezzo effect
« Reply #10 on: April 26, 2005, 03:29:07 PM »
What about the U of Chicago's discovery of negative resistance displayed in crossed carbon polymers?  Could that somehow be used to reduce the diode bias voltage?

Charlie Brown ARN

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Re: Heat conversion by using piezzo effect
« Reply #11 on: April 26, 2005, 07:45:09 PM »
My first response to googleing: crossed carbon polymers negative resistance was   http://wings.buffalo.edu/academic/department/eng/mae/cmrl/Apparent%20negative%20electrical%20resistance%20in%20carbon%20fiber%20composites.pdf    I heard that PDFs were hard on some people's browsers so proceed accordingly. The negative resistance was carefully called apparent rather than true even though with regression analysis ~whatever~ it graphed through 00 , the orgin and was of negative slope. Current going through it heated it, a strong point for realistic evaluation. It had low resistance in AC circuits to MHz frequencies. Semiconductor properties were mentioned. It is an offering of the new discipline of structual electronics.  I am curious about the materials use as an electroplating cathode.

Aloha, Charlie

swankpower

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Re: Heat conversion by using piezzo effect
« Reply #12 on: May 09, 2005, 06:13:50 AM »
I have found some schottky diodes with Vf=375mV made by Agilent...they are quite expensive, but they are quite low threshold voltage.


added minutes later...
from Agilent's website
"The HSCH-534x family of low barrier Beam Lead Schottky diodes are ideally suited for mixer and detector applications from 1-26GHz. These products are suitable for applications that require guaranteed RF tested performance. Vbr=4V. Max. (Vf)=375mV. Max leakage Current (Ir)=400nA. "

swankpower

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Re: Heat conversion by using piezzo effect
« Reply #13 on: May 09, 2005, 06:29:14 AM »
I don't exactly understand why higher voltage generating piezos cannot be used. I can only understand this in an OPEN AIR situation where at ambient pressure and temperature there is a maximum pressure which can be exerted on such a piezo, thus limiting voltage....But if you have a container with the piezo enclosed with larger voltage, you should be able to 'tune' the pressure in the closed container to where the piezo has just enough pressure on it where it is in disequilibrium causing it to push in and out, NOT just push in and stay in. Please forgive me if I forget something completely obvious, as I am not an expert in piezoelectrics.

Kysmett

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Re: Heat conversion by using piezzo effect
« Reply #14 on: May 13, 2005, 04:28:23 PM »
I have done some basic piezo work.  The voltage is produced by a change in shape.  The pressure in a chamber exerts its force universally on the material, so while the pressure is increasing the material compresses.  But it won't decompress unless the pressure is relieved.  So you end up with a direct correlation of votage proportional to the change in shape wich is proportional with the change in pressure.  You would have to oscilate the pressure to get a continuous voltage out.  Otherwise you get a voltage while you set the pressure, but then the material settles at equilibrium with its new environment and voltage drops.

If I am wrong, either in my assesment of the material or that of your idea, please let me know.  I am always ready to learn something new.