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RockyG666 63M
1748 posts
10/19/2013 5:37 pm

Last Read:
10/23/2013 10:38 am

solar death ray

i don't know that i have mentioned the horribly failed attempt that i made to corner the market on unwanted projection tv's in chicago, and so it is best unmentioned. however, there was a big old projection tv being thrown out in the alley the other day, and i happened to wonder what the screen is made of enough to take a look at it.

i need plexiglass to make my solar furnaces. i went looking for plexiglass at the box builder store and 4 x 8 sheets are VERY pricey. especially of the thicker stuff. so i saw this tv, and i wondered if i could use the screen for plexiglass. it looked as if it would work, it was like plexiglass, and so i got a screwdriver and butchered it free. there were 2 panels of plastic.

i looked it up on the web, and it turns out that these things are called fresnel lens. they were invented in france and they are like a giant superpower magnifying glass. if you set up one of the lens' from these projection tv's into the sun as you would set up a regular magnifying glass to burn something, they become a solar death ray.

no kidding. they reach burning temperatures right away. there are videos on utube of people burning stuff with them. it is like a death ray. i tried to find out if the power of them could be harnessed in any way, but could not.

what i am thinking, is if i use this for my solar furnace, it is going to REALLY crank up the heat. i mean, i am not trying to start a fire...but from the way i understand this thing works, like a magnifying glass...if i don't position it like a magnifying glass to focus on that pinpoint of sun that gets that hot magnified.

in other words, if it is not far enough away from something, it shouldn't get hot enough to burn? works in theory, but i don't want to test it on my roof.

but if what i am thinking is correct, using it an inch away from the cans will increase the amount of heat created, as opposed to a regular piece of glass, but not enough to be burning anything. the plans call for fire rated caulk and insulating, so they get really hot anyways.


10/19/2013 8:24 pm

Wow, be careful lol.

"Love is Patient..."

RockyG666 63M
1357 posts
10/20/2013 11:43 am

i think it will be ok. i mean, they are used in the tv on the same concept, it isn't far away enough from the light for it to be in danger of being too focused on.

i looked it up because i was initially afraid they might somehow be treated to filter out the sun, and it was the opposite. i guess they are used in solar applications like heating water.

i am going to make a small one and just set it up in the alley behind my garage and just watch it. if it starts on fire, it won't hurt anything. and if it doesn't, i can measure if it produces any significant heat that i can put to use.

this is really cool because i see these old projection tv's in the garbage all the time. i have seen some variations of the solar furnace design, where they make them to hang right outside of windows and blow in hot air much in the same way a window air conditioner blows in cold.

if this works, i will make a BUNCH of smaller ones and put them everywhere i can. i have litterally 1,000 cans waiting. they will only produce heat when the sun is out, but every bit of heat that they do produce will not show up on my natural gas bill.


10/20/2013 1:04 pm

I try to think of solar ways for heat too. I think this is a good idea. I hope it works.

"Love is Patient..."

RockyG666 63M
1357 posts
10/20/2013 8:05 pm

i keep doing research and getting new ideas. i am going to build this small one with the death ray plastic and put it on the roof to heat the garage.

i have another idea for the church storefront. i am going to build a small light weight one out of drywall and use the window itself as the glass. it is a small south facing window and in back of the stage and it won't be obvious. when the sun shines on those windows as it is, it warms up the church a lot. i think a little solar furnace in one of them will help.


10/21/2013 10:48 am

Cool beans

"Love is Patient..."