I find myself in possession of many rear projection screen TV's, (like 40 or so), and will have to take them all to the recyclers as we switch to flat screens in the rooms.

I got to thinking that the second screen inside each one of these things is a Fresnel lens and it seems a shame for anyone to not have at 'Least' 40 of those hanging around, but what to do with them?
I'm not sure that I have either the time or the give-a-crap to disassemble and remove all of them let alone put them to the use I have in mind, but I thought you guys might get a kick out of the concept.

Some plants don't like as much sunlight as others so I am thinking of constructing the roof of a shade-house portion of a greenhouse from these panels.
This would have the effect of casting an umbra over that section creating a shade house without ever having to replace the shade cloth, which would be nice, it just seems a shame to waste several hundreds of degrees focal points just to cast shade.
So I propose to hang aluminum balls from chains attached to the roof which hang at the focal points.
Even in winter this should radiate quite a lot of heat on sunny days but my main thought was to integrate the drip system to run a trickle of water down the chains which would flash steam once contact with the balls was made.

This should cause the humidity within the greenhouse to remain at semi-tropical levels and may allow for growing many plants which would otherwise not grow at all at this latitude.

Prior art ala [ninteenthly]
[link]
-- 2 fries shy of a happy meal, Oct 03 2020

[hippo] touched on this in the annos. Greenhouse_20Focus
[2 fries shy of a happy meal, Oct 03 2020]

Options https://www.google....dpeg&sclient=psy-ab
Plenty of ideas for re-using old TVs [neutrinos_shadow, Oct 04 2020]

The idea is awesome. Unfortunately, the focus is not a fixed point (damn planet, always turning around when you least expect it...) so you will need a metal sheet, not a ball. Which gives you MORE options, not fewer:
you could have cut-outs in the sheet, so they only heat up at certain times of the day
you could make it a curved shape that, when heated, pops to the "other way" (might need bi-metallic magic), which could open the vents or something
you could use the localised heating to get the water to flow to that area for the steamy bit
(this all assumes good continuous sunshine, which doesn't normally happen...)
Experiments must be done! (Take photos & keep good records.)
Also, linky.
-- neutrinos_shadow, Oct 04 2020


hmmm, curved metal sheets and nitinol actuated lenses within the greenhouse itself would certainly minimize dusting...

I will save a few sets for sure after seeing that!

<puts finishing mental touches on time machine to go back and have some serious words with past guidance councelors>
-- 2 fries shy of a happy meal, Oct 07 2020



random, halfbakery