$5 Home Theater for March Madness

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About: Random Weekend Projects

Just in time for March Madness!  Here's how to convert your Laptop, Smartphone, or Tablet into a makeshift projector.  It's really cheap, and can add a bit of creative fun to your next sports party!

www.thekingofrandom.com

Step 1: Watch the Video!



This project is geared mainly toward college students looking for a way to turn devices they already have into a projector for sporting events or parties.  It's more of a novelty than anything practical, but in my experience, the image is watchable and the idea will hopefully be enjoyed.  If anything, it's a party trick you can pull out for your next get-together with friends.

NOTE: The image projected on the wall will be "mirror image" or "flipped horizontally" from the original image.  This will make any text or numbers appear backward.  The light from the Laptop, Smartphone or Tablet is the only source of light, so as the image is made bigger, the intensity of the light on the screen gets weaker until eventually the image becomes indiscernible.

Step 2: What You'll Need

Aside from already owning a Laptop, Smartphone, or Tablet, you're going to need 3 items to make this projector;

  1. Cardboard
  2. Duct-Tape
  3. Full-page Fresnel Lens

Cardboard:  I got my cardboard box at a Wal-Mart.  I just went into the photo-lab area and asked if they had any boxes I could use for a project.  They had more than they cared to have!  I chose one that was a couple feet long, and the front face was just larger than my iPad.

Tape: For tape, I got black Duck Tape (also from Wal-Mart), but even packing tape or masking tape can work just great!

Fresnel Lens: I found my Fresnel lens on eBay for about $3.99.  Since then, I've seen them as low as $2.99.  The size is somewhere around 8"x10".  These are typically used as full page magnifiers for reading small text.  


Step 3: Cutting the Cardboard

Ideally, we want a hole in the front of the box about 1/2" smaller than the lens.  

I used the actual lens as a template to trace around the edges, then drew another rectangle 1/2" inside the first.  It's this inner rectangle that we'll be cutting out, and it should leave a 1/2" ledge for us to tape the lens onto.

You can also use something like a credit card or hotel key to trace a rectangle in the center. 

When it's all cut out, you should have a left-over piece as seen in the picture, and you may want to hang onto that.

Now you can use some tape to secure the lens on the inside of the box.

NOTE: The grooved part of the lens should be facing inside the box, and the flat smooth side should be facing outward.

Step 4: Finished Projector and Variations for Laptops

When the lens is set, you can close up the box to give it stability.  Your Tablet or Smartphone will go inside and project outward through the lens.

I gave mine a quick paint job to make it a little nicer, and made a projection screen with a piece of 0.02" Hi-Impact Styrene I got from a sign supply company for just over $2.00.  It's 4 feet wide and the black duct-tape made a nice border trim on the plastic sheet.  I had just enough tape left over to put it up on the wall and rig up a make-shift home theater. 

When using a laptop, this configuration will be too small.  I found that a hole could be cut on the back of a different box, and the laptop turned upside down and slid into place.  This is by far the quickest and easiest set-up, and the laptop gives the best results because the screen is the biggest and brightest!

Step 5: Get Ready for Your Video!

The image that gets projected on the screen will be flipped horizontal, and upside down.  You can make it right-side-up by turning your tablet, smartphone or laptop upside down in the projector.

If you're using a tablet like an iPad, you'll also need to go into the settings menu and make sure to lock the rotation of the screen so that it's sideways.  Otherwise when you turn it over, the image won't stay upside down.

Whatever device you're using, you'll also need to bring the brightness up to maximum to get the most light.  If your phone doesn't have an option to lock the screen, you may need to download an app.

To hold the device in the projector, you'll probably want to find something sturdy like a couple of text books, or a sturdy box.  I used a box of tomato paste that was about the size of an iPad.  

Using a couple of rubber bands to secure the device in an "upside-down" position, it's now ready to go in the projector and play your movie!

NOTE: The image should be right-side-up, but it will still be flipped horizontally.  This means that any words or numbers on the screen will still be backward.

Step 6: Success!

I found that using a Laptop works the best, because the screen is larger to begin with, and it can be turned up fairly brightly.  This is good because as the image is made bigger, the intensity of the light on the screen is lessened.  An image of 50" is very watchable on a Laptop, as well as a Tablet about the size of an iPad.  Of course, the closer your bring the projector to the screen, the smaller the image will be, but the brighter and more focused it will become.

I found that if you cover all your windows and close any doors to make sure the room is completely dark, this will help the image appear crisper and brighter. 

Because the Fresnel lens is made flat, there are some optical disadvantages that appear in the image.  For example, the edges of the screen may be a little blurry while the center is in focus.  To address this problem, a shroud can be added to the lens with a rectangular hole in the center about the size of a credit card.  This will choke down the aperture, and dramatically improve the focus.  The trade off is that there will be less light emitted from the projector, so the image on the screen will be dimmed.

A Smartphone works the same way, but the screen size can't go much over 20" or the image is unwatchable.  15" worked great, and 20" was ok.  

Step 7: Conclusion

Since the dissipation of the light reduces the brightness on the screen, it's more of a novelty than anything practical, but in my experience, the image is watchable and the idea will hopefully be enjoyed. 

If anything, it's a party trick you can pull out for your next get-together with friends.

If you haven't see the video yet, it's not too late.  Watch it here!

If you like this project perhaps you'll like some of my others. Check them out at www.thekingofrandom.com

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    63 Discussions

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    mibzman

    4 years ago on Introduction

    Would it severely degrade the quality/brightness if I reflect the image off a mirror at a short distance and then pass that image through the lens so as to fix the horizontal rotation? or would it be a better idea to have a 2nd lens?

    I would use a reflective spray paint on the screen to enhance the specularity and thus increase a perceived brightness. I would use a 3m scotchlight product called 7210 Silver Reflective Liquid. The screen matters more than anything on projection viewing....Just using a white screen absorbs most of the light energy and deflects the images in different directions thus reducing brightness etc.. Good Luck!

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    Blaziken

    5 years ago on Introduction

    my ipod wont put out an image through it why is this

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    jishere

    5 years ago on Introduction

    How might you go about making the projection less blurry? without buying a real projector haha :) great diy!

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    imrobot

    5 years ago on Introduction

    How long would you suggest the box be? I just made it with a 12in (maybe) box which was definitely not long enough for my laptop. Amazing 'ible!

    2 replies

    Thanks, I'm glad you liked it!

    12" worked fine for my laptop, but if you use an iPad or phone, you'll need it longer. My box was probably about 2-1/2' long, and my media source positioned around 1-1/2" from the lens.

    Hmm sorry its taken me so long to get back to you, when I get back home I'll take a picture of it. Maybe I'm doing something wrong?

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    ceaze21

    5 years ago on Introduction

    I just scored a 5 lens deal off Amazon for only $15! http://www.amazon.com/gp/product/B00B0HW99M

    1 reply

    Awesome!

    I saw your comments on the video as well. Thanks for sharing the link , and all the best in your projects and experiments :)

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    Is this lens sheet found in lcd monitors? I took one apart not long ago, wondering if this sheet is in the sheets i got out of it...

    2 replies
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    cryptomaniac

    5 years ago on Introduction

    I made something similar, fifteen years ago, with an old CRT Television, a cardboard box, aluminum foil and a magnifying glass. It worked acceptably for the theater room in the haunted house I was putting together. We even watched Return of the Living Dead on it. if you line the inside of the box with aluminum foil, you *might* be able to get a little more light output.

    1 reply

    Great suggestion! I'd thought about that, but didn't try it .. but I think you're right. In a case like this, even bit helps! Thanks for your comment!

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    Is this lens sheet found in lcd monitors? I took one apart not long ago, wondering if this sheet is in the sheets i got out of it...

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    strings3002

    5 years ago on Introduction

    I wonder if a white translucent panel placed over a mirror would increase the light reflected back to the viewer and make the image more watchable?

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    bulldawgsfan

    5 years ago on Introduction

    I'm having trouble finding a properly sized styrene sheet for under $20 (with shipping) online and I'm not sure if there are any stores near me that sell them. Would poster board work at all?

    Thanks and awesome project!

    1 reply

    Oh yeah, even a white wall will work. It will be a bit blurry around the edges because of the optics of the Fresnel lens, but it's as good as it gets for $3 :)