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Old Sep 12th 2017, 02:13 AM   #1
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Cheap / simple homemade projector

Iím trying to build a relatively cheap and easy projector based on a Cree flashlight. Iíve experimented with cut outs, homemade slides, etc., and am pretty well convinced Iíll need to add a lease or two to make it viable.

Iím hoping to project a relatively large image from say 30 feet away, at night. Probably on the side of a building or on the ground from
A high point.

I eventually want to be able to replicate this cheaply and share instructions for others to do so, but would be thrilled to at least get a prototype going from which I can learn and improve it.

Can anyone help me figure out lenses, distance, etc. - the setup for this?

Thanks so much.
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Old Sep 12th 2017, 06:01 PM   #2
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Cree flashlights are a great innovation very powerful , energy efficient many power outputs , and cheap ... I expect you have one ...switchit on and focus it so it gives the narrowest beam ...

Aimed at a wall two meters away the light is seen as a squarish shape with grid lines on it , about 20 cm square ....

This is the first issue , the light source , the led , is not a point , but a square shape about a mm in dimension ........I would imagine if you put a slide in front of the torch you would not be able to get a sharply focused image projected on a screen ...

Have you tried that???

There are no extra lenses required , nothing that will help get a better image .
IDEALLY The torch is projecting a cone of light that originates from a point .
But because our source is not a point , blurring occurs ...all you can do to reduce this, is have the slide as far away as possible from the torch.

Last edited by oz93666; Sep 12th 2017 at 06:28 PM.
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