Home made projector

[themoron]

I was just browsing though the ebay pages and I thought I would look up projectors. I came across this item http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=802118831 . Could anybody tell me if this is possible to do or is it just a load of rubbish?

thanks

themoron

 

[buns]

it is possible and it is also a load of rubbish. The results may be big, but the image would also be awful.

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[simon69]

I think "pants" is the word you are looking for!

 

[Chris Frost]

Themoron,
What you've come across is a variation of a product commonly known as a True Image Projector (a.k.a. TIP or Epidiascope).

TIPs are used a lot in classrooms and for training where you want to show an enlarged image of some 3D object, e.g. a watch/remote control/circuit board. They work by reflecting light off the object and using a lens to magnify and focus it.

The plans for the version in the Ebay auction will probably use a portable TV as the light source set inside a sealed box, then magnify that image using a very large lens. It's the same principle as a CRT projector, but it won't be as bright and the sharpness very much depends on the quality (and cost) of the lens used.

The Ebay auction is only for the plans to make one, not the product itself. It doesn't include the cost of materails and your labour.

Regards

 

[DVDcake]

Its amazing that people still want to experiment with these projectors. I tried doing this sort of thing ten years ago using a large glass magnifying lense surrounded by a bin liner attached to a television. This produced an image which filled a whole wall.
Just a few problems though, the image was so dim I had to experiment at night and came it out on the wall backward and upside down so to see it right way up the tv would have to go upside down. Not the perfect operating condition for a top vented heat producing device I think. People are now trying to do this with large Fresnel lenses made of flat plastic with concentric rings cut into them but I doult this will improve the results much.

The reason manufactures produce three tube CRT projectors is to provide sufficent image brightness and even these need to be used in conditions of low background light. To get a single tube device to emit sufficient light would require an excessively high tube voltage and could lead to X-rays eminating from it.

 

[themoron]

Thanks for all the feedback guys, I am really planning on getting an LCD projector although the 'plans' were so much cheaper than the projectors I was looking at. I thought it was a con, though I couldn't work out how you could make a projector at home.

Thanks again

themoron )