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 Posted: Jul 31, 2007 - 11:58 PM |
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Joined: Jun 27, 2006
Posts: 115
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| Anybody up on the most efficient ways to convert mechanical to electrical energy to power a pico power AVR? With running current in the uamps I suppose it wouldn't be too hard. How do those "shake" flashlights work? Could the energy be dumped into a super cap? Anybody know what the basic equation are that I need to use to figure out the conversions for, say, some type of body movement to watt-seconds? |
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Posted: Aug 01, 2007 - 12:04 AM |
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Joined: Dec 17, 2005
Posts: 1498
Location: Europe- Estonia- Tallinn
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what kind of mechanical energy do you have? shake? rotation? linear?
It's actually all about magnets and coils  the easiest I could think of is DC motor connected to a prop (like a plane has) and just apply wind. |
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Posted: Aug 01, 2007 - 12:21 AM |
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Joined: Sep 04, 2002
Posts: 21253
Location: Orlando Florida
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| How about a couple of those Honeywell furnace thermopiles that sit in the pilot light and put out 2V to hold the pilot valve open. One or two of those and a fresnel lense and a sunny parking lot? |
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Posted: Aug 01, 2007 - 12:46 AM |
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Joined: Jan 06, 2007
Posts: 374
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There are also piezoelectrics.
Quote:
Anybody know what the basic equation are that I need to use to figure out the conversions for, say, some type of body movement to watt-seconds?
It would depend on how you are generating/harvesting the energy.
This might be of interest:
http://peswiki.com/energy/Directory:Ocean_Wave_Energy |
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Posted: Aug 01, 2007 - 12:53 AM |
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Joined: Jun 27, 2006
Posts: 115
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bloody-orc wrote:
what kind of mechanical energy do you have? shake? rotation? linear?
It's actually all about magnets and coils the easiest I could think of is DC motor connected to a prop (like a plane has) and just apply wind.
The mechanical energy I have is sports motions, like swinging a tennis racket, or golf swing, the AVR only needs to work 10 seconds or so per motion. |
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Posted: Aug 01, 2007 - 12:56 AM |
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Joined: Jul 02, 2005
Posts: 5933
Location: Melbourne, Australia
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joepierson wrote:
I need to use to figure out the conversions for, say, some type of body movement to watt-seconds?
Propellor hat and convert the rotary motion into electricity.  I think that there is a photo of the early production units at ...
http://www.geekculture.com/geekcultures ... /caps.html |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Aug 01, 2007 - 01:03 AM |
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Joined: Jun 27, 2006
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nanovate wrote:
There are also piezoelectrics.
Quote:
Anybody know what the basic equation are that I need to use to figure out the conversions for, say, some type of body movement to watt-seconds?
It would depend on how you are generating/harvesting the energy.
This might be of interest:
http://peswiki.com/energy/Directory:Ocean_Wave_Energy
thanks! that is the type of info I was looking for |
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Posted: Aug 01, 2007 - 01:59 AM |
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Joined: Nov 17, 2004
Posts: 6137
Location: Great Smokey Mountains.
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Posted: Aug 01, 2007 - 02:54 AM |
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Joined: Aug 10, 2003
Posts: 14
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You can also use thermoelectrics to generate current. This relies on a temperature gradient being present, but that gradient could easily be established by, say, body heat transferred to the outer surface of a grip. Problem here is cost and the fact that your golf club won't work in Arizona or Florida. 
For an electromechanical solution, consider using rotational instead of linear stator/coil displacement. For the target device you mentioned (raquets, clubs), the shift in center-of-mass that will occur as the stator of a linear "shake generator" slides across its throw will most likely be perceived as an annoyance by the user. A rotational generator (rotation induced by the inertia of an offset mass) would still modify center-of-mass, but the absolute displacement could be made smaller.
Other sources: wind, solar. I know you wanted to use mechanical energy, but unless your application will spend its life in darkness, a small, discreet solar cell might be sufficient. |
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Posted: Aug 01, 2007 - 03:04 AM |
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Joined: Sep 04, 2002
Posts: 21253
Location: Orlando Florida
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| 1 horsepower = 746 watts = 550 ft-lbs per sec or 33000 ft-lb per minute. So if you lift up a 55lb bag of stuff onto a 1 ft pallette every sec, you are putting out 1/10th HP. If you spin an alternator on an exercise bike, you can put out 100 watts for a while, or a shorter burst for less than a while. I hear Lance Armstring can hump out 600 watts for hours. So if you can work a shovel at 100 watts for 10 hrs, thats a KW-hr. Worth 15 cents. Think Americans get paid too much? |
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Posted: Aug 01, 2007 - 03:04 AM |
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Joined: Sep 11, 2006
Posts: 163
Location: Kamuela, HI
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My guess is sbaugustine's solar cell approach would also be the easiest to arrange. Almost everything I've seen that converts mechanical motion into electricity is, at some level, bulky. See what kind of power output you get off of a thin film flexible cell in the environment you expect to use this in, and size accordingly. Then see if you can make something that'll convert motion into electricity with the same kind of specs for that size/weight or less. It'll be tough.
Lots of vendors out there for thin film solar cells, so I won't go into a list. A quick Google search would give you dozens of vendors.
Tom |
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Posted: Aug 01, 2007 - 03:21 AM |
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Joined: Jul 02, 2005
Posts: 5933
Location: Melbourne, Australia
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bobgardner wrote:
So if you can work a shovel at 100 watts for 10 hrs, thats a KW-hr. Worth 15 cents. Think Americans get paid too much?
And for those us disconnected from any manual form of paid labour, what is the 3 watts dissipated by the brain worth?
Thanks for the reality check.... |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Aug 01, 2007 - 05:27 AM |
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Joined: Sep 04, 2002
Posts: 21253
Location: Orlando Florida
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| Good question. Is the guy that does the brain work more important to the project than the guy working the shovel? If its a 2 man job, they both better show up for work. One cant get along with out the other. One of em knows where to put the hole and how deep, the other knows how to make that happen. If you have a programmer and a machinist working on a widget that has a metal box and a microcontroller, which one can you do without? So should they both be paid the same? |
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