Thread: A New Take on Lighting

I saw that on another forum. The light panel from a flat screen is the nearest thing to natural light. They make a great artificial skylight.
Regards
John

Great video on making one here

wow watched the video ,how good was the lighting that would last for a long time, made from pieces of junk and cost peanuts to run.

The thing that makes large screen TV/monitors useful is the Fresnel (pronounced Fre-nel) lens or sheet - which as the video shows redirects more light in the forward direction and will provide more even lighting and intense lighting with distance from the light source. These lenses are used in lighthouses for that purpose. They can also be used as slim line magnifiers like the credit card size and thickness magnifiers that are found on ebay
However, the illuminance (lux) at bench top level is still be limited by the total number of individual LEDs used, and the area over which they are distributed.
Fresnel lenses are actually not very efficient so not all the light produced is directed forward and some is converted to heat inside the lens.

The large screen TV example on the video uses about 40 individual LEDs inside it which means, assuming the brightest LEDs have been used, the light out will be limited to a maximum of about 4000 lumens. Compare this with the ~100 LEDs (10,000 lumens) used on the newish panels available.
The benefit of course is that when the 4000 lumens going through a Fresnel will mostly be in the forward direction.that light
Smaller TVs, PC and Laptop screens will have fewer LED elements and won't be as bright

I really like the reuse of a wasted resource idea, but by the time you go to the trouble of dismantling a large screen or computer TV, getting rid of the unnecessary electronics and optical parts, working out how to power the LEDs and avoid getting electrocuted etc you might as well beef up the number of LEDs , or just remove and use the Fresnel lens in a more compact LED panel.
Or you could just put a piece of a Fresnel lens in front of an existing panel - I am rather keen to try a piece in front of my $13, 10,000 lumen, Chinese panel.

The other issues to consider are size and shadows .
One place I need good lighting in my shed is inside my welding booth but there is no way I could fit a large screen TV inside that space.
The large screen TV light will only help reduce shadows if it is relatively close - ie above a lathe is a good use, but when its further away there will still issues with shadows.
I use a moveable LED spot to direct the lighting close to where I need it and to minimise shadows.

Nevertheless I will be on the look out for large screen TVs in the next council chuck out and will experiment - hours of endless fun ahead

I pulled one apart about a year ago and found that the LED strings required 96v dc to run them. As Bob said, there are not many LEDs in a panel. I dabble a little in electronics but decided to bin it and spend my time on other things more important. I have LED lights in the shed already.

Originally Posted by Cal

I pulled one apart about a year ago and found that the LED strings required 96v dc to run them. As Bob said, there are not many LEDs in a panel. I dabble a little in electronics but decided to bin it and spend my time on other things more important. I have LED lights in the shed already.

The Video mentions this in passing. 96V DC is potentially dangerous stuff and suggests the LED are linked in series so if one LED dies they all die. The fellow in the video suggests replacing these with strings of parallel connected LEDs but then you will need a different power supply and again its almost like building a panel from scratch.

Yep, that’s exactly why I didn’t bother. Too dangerous and too much messing around with other LED strings to warrant the effort, if I want more lights I will just go and buy them