Energy harvesting IC...

[mtripoli]

Just saw this on the Linear Technology site and thought it was interesting... has many interesting application ideas...
http://cds.linear.com/docs/Datasheet/35881f.pdf

Mike Tripoli

P.S. I understand there is a new forum being worked out? Just a thought; maybe a category for posting new IC's and such posted outside of the "Adverts" section for "finds" like this one...

[Byte_Butcher]

Well that's an interesting device. "Free" electricity from vibrational noise...
Interesting enough that I tossed 2 of them into my Digikey cart for future experimentation.

Thanks for the link.


steve

[ScaleRobotics]

I would be interested to know how it works with some cheap piezo's. The piezo they specify in the data sheet costs $69.00. You could make a pretty nice solar/battery system for that price!

[mtripoli]

Well that's an interesting device. "Free" electricity from vibrational noise...
Interesting enough that I tossed 2 of them into my Digikey cart for future experimentation.

Thanks for the link.


steve

You beat me to it...


I think it's worth trying with some cheap piezo's. I have a bunch of the things around here...

Mike Tripoli

[Byte_Butcher]

Yeah, I'd try first with cheap piezos out of "noise making" devices.

It should be easy enough to connect a piezo to the 'scope and see what kind of voltages it produces when you whack it...

steve

[falingtrea]

Check out the alternate power sources section on page 16 of the data sheet. You can connect it directly to 110AC. Or harvest from a Flourescent light fixture, or a solar panel, or a thermoelectric device. Not just the Piezo.

[Byte_Butcher]

Yeah, it's got lots of interesting options. That's why I got 2 to play with.
I'll lay out a little circuit board for it and slip it into my order next time I need boards for something.

steve

[mtripoli]

I saw on a TV show some time ago about a university student somewhere (full of good information in that statement) that had made tiles to place in public that generated electricity when people walked on them. I have to say I said to myself "yeah, right - practical as hell"... with a device like this... hmmm...

I kinda' believe there must be a device coming on the consumer market that uses this thing or a private company has it embedded in a product. It just doesn't strike me as a device that would get a budget just because someone thought it *could* make money. I did a Google search and didn't find it referenced in anything, yet...

[ScaleRobotics]

Well, you guys have me quite curious. So I hooked the mini piezo buzzer I had up to the scope. And if I cause air to whistle through it, I can get up to about 500 mV. That was about the peak for my mini piezo though.

Then after reading your post about thermo electric, I pulled out one of my peltier devices. Mine has heat sinks on both sides, so you may be able to generate more electricity with just a bare peltier using this method. I was able to get to about 1.025 Volts using hot tap water in a Ziploc ® one side, and an ice pack on the other. Total guess of about 100 degrees difference. I was sort of hoping to see a little more volts out of this one.

Walter

[Bruce]

Walter,

The piezo they specify in the data sheet costs $69.00

Yikes! Where did you find one at? I would like to grab a data sheet to see specs on this part. Hopefully it can be crossed to some similar part a tad cheaper.

[ScaleRobotics]

Their site is a bit hard to navigate, but here is one that is referenced
http://www.advancedcerametrics.com/pages/product_line

And here is the other one (but it is double the price)
http://www.piezo.com/prodexg1brass.html#priceinfo

I have not looked at the data sheet. Mostly because of sticker shock. Let us know what you find out.

Walter

EDIT:

Some more info here: http://www.piezo.com/tech2intropiezo...ntroGenerators

[Bruce]

Thanks Walter. Looks like I won't be using these any time soon. You're definitely not going to replace any of these high-end piezos with the little piezo buzzer elements.

I'll stick with a super cap with a small solar charge panel until they make the technology a LOT cheaper. I was really interested until I saw the pricing.

[Demon]

... I pulled out one of my peltier devices. Mine has heat sinks on both sides, so you may be able to generate more electricity with just a bare peltier using this method. I was able to get to about 1.025 Volts using hot tap water in a Ziploc ® one side, and an ice pack on the other. Total guess of about 100 degrees difference. I was sort of hoping to see a little more volts out of this one.

Walter

Ok, so now you got me curious too. Can you elaborate on the peltier, never seen one. Pics?


Shoot, if temperature differences can generate energy, I live in Quebec. I can stick a few of these in some windows during winter.

Come to think about it, you can also use it in reverse during summer; one end outside, one end going a few feet deep, maybe into concrete a few feet underground.

EDIT: A quick google got me this:

http://en.wikipedia.org/wiki/Thermoelectric_generator

Thermogenerators are devices which convert heat (temperature differences) directly into electrical energy. For the most part, this term is synonymous with "thermoelectric generator" (TEG) and rarely used in English. Essentially they work on the principle of the Seebeck effect, with typical efficiencies of around 5-10%. Older Seebeck-based devices used bimetallic junctions and were bulky while more recent devices use bismuth telluride (Bi2Te3) semiconductor p-n junctions and can have thicknesses in the millimeter range. These are solid state devices and unlike dynamos have no moving parts, with the occasional exception of a fan.


EDIT SOME MORE: Ok, after seeing mention of TEC, I remembered seeing that term somewhere before, this is what I use to cool the cpu in my gamer pc:

http://www.legitreviews.com/article/491/1/

[ScaleRobotics]

Hey Robert,

That's pretty much it. The short description of a peltier is :A Peltier cooler/heater or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other.

Some cars with heated/cooled drink holders use them, and some mini cooled coolers use them. Reverse the polarity, and you reverse the side that is hot. In astronomy cameras, they stack them to get the camera imager really, really cold. That way they can take 20 minute exposures without very much noise.

Maybe a device that was made to generate thermo electric power would be able to generate more power. I used a cold pack on one side, and the hottest tap water I could get on the other, but I was only able to generate about a volt. Not very efficient for about a 100 degree difference. I had hoped it would have been another volt or two out of it at that temp difference.

Here is a picture of what I used, and then the actual device:


And just a peltier normal device without heatsinks:

http://search.digikey.com/scripts/Dk...me=102-1668-ND

This explains a little more about them, and their inefficiencies.
http://en.wikipedia.org/wiki/Thermoelectric_cooling

[Demon]

Did you check the datasheet for your model?

It's talking about 3A 15.4V max at delta Tmax 66c @ 27c.

Ok, so I'm not sure how to interpret all that, but is it possible that you went over specs by going up to a 100c difference?

[ScaleRobotics]

Did you check the datasheet for your model?

It's talking about 3A 15.4V max at delta Tmax 66c @ 27c.

Ok, so I'm not sure how to interpret all that, but is it possible that you went over specs by going up to a 100c difference?

Thanks Robert,

I was working in the 100 degrees F range.
I don't really know which model mine has inside it. I probably would get more voltage at 150 degrees F difference. But in a real world scenario, it would be hard to produce this naturally I would think. Other than placing one side of it on my muffler or something .... and then I could just use the alternator.

Mine is better suited for building a 12 to 15 volt dc refrigerated cooler. I think that is what mine was originally built for. I bought mine at a surplus electronics store.

Walter

[ScaleRobotics]

Here is an energy harvesting product that Sparkfun sells, based on the LTC3588. They have some lower cost piezo transducers. But I am sure a lot lower ratings. http://www.sparkfun.com/commerce/pro...oducts_id=9946



Features:

• 950nA Input Quiescent Current (Output in Regulation – No Load)
• 450nA Input Quiescent Current in UVLO\
• 2.7V to 20V Input Operating Range
• Integrated Low-Loss Full-Wave Bridge Rectifier Up to 100mA of Output Current
• Selectable Output Voltages of 1.8V, 2.5V, 3.3V, 3.6V
• High Efficiency Integrated Hysteretic Buck DC/DC
• Input Protective Shunt – Up to 25mA Pull-Down at VIN ≥ 20V
• Wide Input Undervoltage Lockout (UVLO) Range

Just as interesting to me was their mini 8 pin soic 4 volt solar cell. Pretty cute.
http://www.sparkfun.com/commerce/pro...oducts_id=9962