Using magnifying glass to heat up water...

Why not just put the water in a black pot, and place it outside? Should be easy enough to do...

Ok, so put a panel on your roof.

Androcles

Yeah, well, in the West we don't expect our women to carry cauldrons on their heads anymore, and I'm not doing it just to get a shower. Androcles

Stand outside and keep that magnifier focused in the correct spot as the earth turns... you can do it.

Damn! Why are all the good ideas already taken?

PD

Given that you can already boil water without the magnifying glass (but don't want to, as then mineral deposits tend to block the pipes on the collector plate), if you just want to heat water, why not just get a standard solar water heater?

OTOH, there are solar furnaces out there, usually with mirrors rather than magnifying glasses.

Here's one that isn't taken, as far as I know. Whether or not it is "good" is another matter. I've always wanted a walker-powered battery recharger, so I can keep my digital camera operational while on a hike or long walk. OK, so there are some solar-powered ones, but they would not be of much use in a cloudy/rainy climate, as is often the case in a place like the west coast of Vancouver Island or in the Norwegian Fjordes. Wouldn't it be nice to have some type of gadget attached to one's thighs or shins that would, over a period of several hours, recharge a battery? (I don't know if it is possible; it is just something that would be great to own.)

R.G. Vickson

Look up self-winding watches. I believe there are products more along the specifics of what you mention, though. I've seen them in catalogs.

PD

Yes, it's been done. :-)

The US Army is working on such a device.

Sorry.

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| > Damn! Why are all the good ideas already taken? | | Here's one that isn't taken, as far as I know. Whether or not it is | "good" is another matter. I've always wanted a walker-powered battery | recharger, so I can keep my digital camera operational while on a hike | or long walk. OK, so there are some solar-powered ones, but they would | not be of much use in a cloudy/rainy climate, as is often the case in a | place like the west coast of Vancouver Island or in the Norwegian | Fjordes. Wouldn't it be nice to have some type of gadget attached to | one's thighs or shins that would, over a period of several hours, | recharge a battery? (I don't know if it is possible; it is just | something that would be great to own.) | | R.G. Vickson

It is very possible and very simple. The kind of energy involved should be comparable with a self-winding watch:

The simplest method would be the piezoelectric effect. Androcles.

Assuming you want to heat water for domestic use such as several tens of gallons and not 5 grams of water for some exotic experiment or application. In a peak sunny day, there is about 1000Watt/square meter of solar energy striking the Earth surface.

The magnifying glass, a lens, would intercept a large area of sun rays and focuses them on a small area where the water is placed.

Is a lot simpler to spread the water in a tin layer over the same intercepted area. Usually is done with many pipes inside a black box with a glass on top just like a green house. The box sits flat on the roof top, intercept the radiation and reflect as little as possible.

No 2 tons lens costing $$$$$ suspended several feet above the water vessel, no loss through the expensive optical glass no wind load on the lens with the danger of wheeling around the neighborhood, no two surfaces to clean.

It is possible but there are better solutions.

MG

On Thu, 10 Aug 2006 00:47:35 +0100, Ben Newsam Gave us:

The military uses motion operated battery pack chargers.

On Thu, 10 Aug 2006 00:35:02 GMT, snipped-for-privacy@specsol.spam.sux.com Gave us:

It is actually being done.

On Thu, 10 Aug 2006 01:19:01 GMT, "Sorcerer" Gave us:

Like with the magnifying glass, you have to know where to apply what energy. A large fresnel sheet and a matte black container for the water is far better than a high temp focussed point, and clear water surfaces.

A piezo stack usually requires quite a compressive force, and will put out hundreds of volts. Not really a good choice considering the force required. A contraption that converts long throw motion into high compressive force short throw motion is going to be problematic.

Best just to make a linear motor and use it as a generator.

Similar to those flashlights one just shakes a few times for a super cap bank to charge up from an inductive charging generator, and a slide slug style "rotor". ala linear motor.

On Thu, 10 Aug 2006 06:57:57 +1000, "Timo A. Nieminen" Gave us:

There are several around the world. We have one that can bore an eight inch diameter hole through a couple inches of steel in VERY short order. A field full of mirrors all converge on a final focussing array, sending it down a tower to the target at several thousand degrees C.

There was a device developed by a young man in Britain a few years ago. His approach was similar to those LED torches that you shake to charge them up, except that he used a metal ball in a circular tube, with coils round the tube. That way, more or less any motion would cause the ball to roll in the tube. Jogging seemed to wrok well enough.

As I understand it the poster wanted sufficient energy to operate a digital camera while hiking in cloudy conditions around Norway and Vancouver, I think it was, and his proposed energy source was to be his own muscle. Perhaps all he really needs is a camera based on this old idea.

Androcles

? "PD" ?????? ??? ?????? news: snipped-for-privacy@h48g2000cwc.googlegroups.com...

There's no need to reinvent the wheel, heliotherma are a domestic standard in greece for more than 3 decades, resulting in major power savings.We have one in all our 3 homes.It would be a shame to use oil, gas or electricity for hot water when the sun is burning 90 degrees hot.

this is only in greek but still you can see the photo.

-- Tzortzakakis Dimitrios major in electrical engineering,freelance electrician

542nd mechanized infantry batallion dimtzort AT otenet DOT gr