Instructables

$5 Home Theater for March Madness

Featured
Picture of $5 Home Theater for March Madness
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
 
Remove these adsRemove these ads by Signing Up

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

Picture of What You'll Need
2.jpg
3.jpg
4.jpg
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

Picture of Cutting The Cardboard
6.jpg
7.jpg
8.jpg
9.jpg
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

Picture of Finished Projector and Variations for Laptops
12.jpg
24.jpg
25.jpg
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!

Picture of Success!
21.jpg
26.jpg
27.jpg
23.jpg
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

Picture of 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
mibz man4 months ago
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!
Blaziken9 months ago
my ipod wont put out an image through it why is this
jishere9 months ago
How might you go about making the projection less blurry? without buying a real projector haha :) great diy!
imrobot1 year ago
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!
The King of Random (author)  imrobot1 year ago
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?
ceaze211 year ago
I just scored a 5 lens deal off Amazon for only $15! http://www.amazon.com/gp/product/B00B0HW99M
The King of Random (author)  ceaze211 year ago
Awesome!

I saw your comments on the video as well. Thanks for sharing the link , and all the best in your projects and experiments :)
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...
No, the LCD is different. This is a Fresnel lens, thanks for asking!
Ah, so like from a rear projection tv...
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.
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!
Devin super tramp, best guy
Yeah :)
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...
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?
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!
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 :)
Treknology1 year ago
A friend and I are working on a similar project using real lenses from an OHP and a rear-screen projector. The Freznel lens has always been a popular way of spreading or concentrating light but, as it is a set of concentric "ring lenses" (to keep it flat), that is the main cause of the distortions that plague these projects.

Thanks for showing the world that it can be done. Just make sure that your "source" monitor is well ventilated.

The Freznel version was highly popular with standard analog TV because there was no significant detail for it to mess up.

Our project will involve high-intensity LED light, using the Freznel to focus that through a dismembered LCD monitor, and then using the "real" lenses to properly focus that image on the screen.

1) Don't hold your breath. Other projects are in the queued up ahead.
2) Soldering all those LEDs is going to take much time!

I checked out your Scorcher lens, and badly want one, but I don't think it would help this project. Enjoy your big-screen pictures.
PS: Mine won't come in under $5 :(
The King of Random (author)  Treknology1 year ago
Sounds like an awesome project. Do you have any advice on where to get an OHP for cheap or free? I haven't the slightest clue.
I came across one at a local Thrift store a couple weeks ago. They had it priced at something between $20-$50 and it was marked as working (though I didn't hook it up myself to check.) I've also seen them pop up on Craigslist a few times. You could also talk to someone in the upper echelons of your local school district and see if they have any old or unused units collecting dust in storage that you could take off their hands for a donation to the school. That's a double win!
The King of Random (author)  Cylvre1 year ago
That's a great idea :) Thanks!
I was extremely lucky to score a pair of them as they were being discarded from an educational institution. I do see them on eBay from time to time but, just like trying to get a microfiche reader, the freight is what kills.

The advantage of the OHP lens is that it's already optimized for a larger projection panel (about 12" square), whereas most projectors that one can salvaged (slides, etc.) will only have lenses that are optimized for 1" square.

The biggest disadvantage I have seen in digital projectors is the use of a "standard" hot filament bulb, and an extremely long light path to protect the objective from the heat.
The King of Random (author)  Treknology1 year ago
Ok great! Thanks for your quick reply!
No worries. As these were never a "consumer" item, there aren't many of them lying around....
giocad1 year ago
a nice idea
The King of Random (author)  giocad1 year ago
Thanks :) Simple anyway.
poulman1 year ago
Cute!
In my couuntry, fresnels cost too much. So, it wouldn't be so cheap.
Mine is a little bit expensive. It costed more than $300 in parts.
Here are some photos:
http://poulios.comeze.com/imagicon2.html
The King of Random (author)  poulman1 year ago
Awesome quality! Yours produces a much much better picture because you can add strong light behind the LCD and have a better lens. I couldn't do that with this project, so the benefit is that it's quick, cheap, and requires no modification.

Nice looking project btw!
Thanks man!
I realy like your project for its simplicity and low cost.
I'm sure it comes useful many times.
great work as always!
Can this be done with conventional glass convex lenses? Finding a fresnel lens is pretty difficult in my country.
I thought you'd have added it in lamps and lighting contest and scrolled up to vote but didn't see the button. :)
Hi Antzy! Yes, conventional lenses will work even better! They are just heavier and awkward to work with, and more expensive. But if you have them, use them. Also, if they are smaller, they won't project as much light, but they will have a better focused picture.
I have some lenses from broken binoculars. Will try it with them... Thanks :)
Awesome! Please let me know how it works!
maxhuey1 year ago
I bought full page Fresnel Lens at Dollar store for $1.50
The King of Random (author)  maxhuey1 year ago
Wow! Great find!
Pro

Get More Out of Instructables

Already have an Account?

close

PDF Downloads
As a Pro member, you will gain access to download any Instructable in the PDF format. You also have the ability to customize your PDF download.

Upgrade to Pro today!