…and How To Make One.

If you want a quick, cheap, big screen or projection solution, you're better off getting a Torpedo Video Projector or a Zoombox. I prefer the Torpedo. These are basically toys, but you can do a lot with them. I have reviews of the Torpedo here and here as well as a home made screen here.

Don’t waste your time or money on those ebay ads. They sell you “plans” for information you can already find for FREE on the internet. Sure, they put work into their “plans” but you don’t need to be a rocket scientist to be able to figure out how to make this. They also make outrageous claims about 6x and even 6.5x magnification which is irrelevant and MISLEADING.

Research fresnel lens and you’ll find that the main purpose of this type of lens is to project LIGHT like in lighthouses and car headlights. They are not meant for images (optics). What’s really important (since it’s projecting LIGHT and not maginifying “images") is the FOCAL LENGTH, groove pitch, and things like that.

I was sent a 330mm focal length, supposed “6x magnification", Fresnel lens by an eBay merchant. I got, pretty much, the same results in “magnification” (aka: screen size) with a beat up, dirty, scratched, old “page magnifier” that I had laying around with a focal length of 370mm (with no difference in quality of the projected image either).

I’ve written to some of the eBay sellers asking them what the overall size, pitch groove and focal length of the lens that they supply is. Here’s the results of my queries:

godrules_net: Inquired twice, no reply.

ladyclark122: “Our new custom manufactured lenses are measured 7.25 x 10.25. Thanks” Great, what about the rest of my question which was conveniently overlooked…heh. I wrote back asking about the rest of my question. I never got a reply.

therightpurchase4you: “Please look into my eBay shop, all details are there about the pvc / Fresnel lens". Which I did. It’s the 300mm “3x” lens (better than what I was sent but costs only US$6.59 -including shipping- from 3dlens.com [lens #406]).

thgadgets: No reply to date.

littlemadi: Inquired twice, no reply.

Since the seller I got my lens from refuses to answer my question (and I know he’s getting my emails since he’s communicating with me about a different subject), how do I know the focal length of the lens he sent me? How do I know the focal length of the dirty, scratched, beat up old “page magnifier” I had laying around? Easy. The way to find the focal length of a Fresnel lens is to use a light source, like a table lamp. Have the lamp across the room, put the Fresnel lens next to an opposite wall and slowly move the lens from the wall until you see an image of the lamp come into focus on the wall. Measure the distance from the wall to the lens…that will be your focal length. Then use a metric converter to convert the inches into millimeters. The lens I received measured 330mm from the focused image on the wall to the lens.

How To Make Your Own Big Screen TV Projector

All you need is some sturdy cardboard or better yet, *matte black foam core board*, matte black paint (if you use cardboard), duct tape or a hot glue gun, a small TV and a Fresnel lens. If you don’t want to use black paint, a really good alternative is black felt. Throw length (the distance from the lens to the screen) is important. If you want the projector behind you, you should probably look for a Fresnel with a focal length of about 500mm (not the 300mm - 330mm you find on eBay). I plan on getting the Large Fresnel Lens #F550 from 3dlens.com.

http://tv.groups.yahoo.com/group/DIYProjectionTV/ Discussion Group on Yahoo. Pictures, plans, tips, tricks and recommendations. Suggests NOT to use a Fresnel lens (which makes sense)! They recommend a 100mm triplet lens with focal length of 500mm. Join today!

http://worldtvpc.com/projector These are the basic plans they sell on Ebay.

http://www.fresnellens.net/ These are the basic plans they sell on Ebay.

http://www.gookalian.com/projector/gallery.html These are pictures of a completed projector.

http://www.diyprojectiontv.8k.com Several different methods for a projector.

http://www.stereo3d.com/discus/messages/21/385.html?1089606575 Excellent read.

If you want to first try this with a Fresnel lens, get one here.

Here’s my design for the Fresnel lens projector (which has a much smaller profile than the monstrosity that everyone else seems to be using) which will display the image correctly onto your wall. I did this based on the principal of a common periscope.

This design is meant for a 13″- 15″ TV with a short throw distance (the 330 mm Fresnel) and is currently being used on my 15″ TV in my bedroom.

This will give you an idea of what my design consists of. It’s like the other designs, only it’s on it’s side (rather than sticking straight up into the air) when the TV is on it’s back. This will give you a lower profile when projecting onto a screen (since a short throw requires the projector to be close to the screen).

CLICK HERE FOR THE INSTRUCTIONS

These are really basic instructions. You should be able to figure out how to put it together based on the drawings and the pictures provided in the links above. It’s not rocket science.

http://www.diyprojectorcompany.com/theory/calculator.htm A calculator to determine things like screen size, throw distance, lens size etc. A Wonderful tool!!!

RESULTS

Pictures have been posted to the Yahoo! group mentioned above. I found a video at YouTube. What you see, briefly, near the end of the video and also in the preview for the video (as shown below), is the same quality of the results I obtained with the cheap “6x magnification” 330mm lens that I received from an eBay merchant.

WARNING: Video has ATROCIOUS music and it’s really loud! You might want to turn off the sound on your speakers before you press play.

Getting the Best Picture

Join the Yahoo! group mentioned above to get access to tips, tricks and plans for getting the best picture possible out of this kind of projector.

What You Can Do With This Projector

the Fresnel projector is fun to make. The quality isn’t fantastic, but it’s fun. It would be great for the kid’s bedroom or play room.

I decided to use it in my bedroom until I got the Torpedo Video Projector. I have a canopy bed and I put a sheet between the back posts and put my fresnel projector on the night stand next to my bed. I watched big screen TV in bed with this for quite a while till I got the Torpedo. Since I’m near-sighted, this set-up makes watching TV easier for me than trying to focus on a tiny 15″ TV from across the room without my glasses on. Blurry “up close and personal” is easier on me than blurry from far away and tiny. The image, with the screen at the foot of my bed and the fresnel projector 5 Feet from the screen, is 63″!

The Fresnel lens projector is not recommended for anything under 13".

Enhance Holiday Displays

The Fresnel and Torpedo projectors would be ideal for inexpensive special effects during holidays by projecting images onto the side of your house (as long as there isn’t a lot of other ambient lighting, like street lights) or even in a room that is viewable from the outside of your house. The possibilities for this is endless…ghostly scenes, Christmas scenes, etc. Projecting moving images onto a screen in a dark room (or even by “rear projection” by using a piece of frosted plexiglass or a shower curtain as the screen) and opening your drapes wide so everyone outside can see it, will only enhance any holiday display!

Other Types of “Do It Yourself” Projectors

You can make your own projector out of an old Over Head Projector and an LCD panel, which I think is the easiest since no construction or tools are required to get this system going and it won’t break the bank. The reason this is so affordable is because both of these things are considered “obsolete” by today’s technology, but you know what? This stuff still works! I found both items on Ebay and also on Craigslist. The person on Craigslist said the only reason he was selling his was because all the classrooms in his school now have LCD projectors (which cost hundreds if not thousands of dollars) and he was selling it for only $50. Basically, an LCD projector is exactly what you end up with by using “outdated technology” such as an overhead projector combined with an LCD panel, only for hella cheaper! As soon as my budget allows, I’ll be doing exactly this.

For you really adventurous types who would like to make an LCD projector from scratch, check this out:

http://www.diyprojectorcompany.com/designs/ They have plans, shopping links and forums.

More information about this process can also be found at AV FORUMS.

Get tons more information simply by researching it.

Thank you so much for visiting my page, I hope this has helped you. Have fun and I hope you enjoy your DIY Projector!