There are a couple of different ways you can make a homemade video projector. You can design a miniature one that you can take anywhere or a full-size one that you can use like a movie projector. The basics of both involve sending a video image through a projection frame and focusing it with lenses. Since a Fresnel lens is essentially multiple lenses fixed together, it works great for this. The lens will help you turn a small media player or a TV set into a homemade projector.
Take a small media player, like an iPod or Zune, that plays videos (and possibly photos) with a sharp picture screen.
Make a cardboard frame, similar to a box with open ends, that is the same shape and size as the medial player's screen and about 3 inches long. Tape the frame to the screen, taping it all the way around to make sure no light escapes where the frame meets the screen.
Assemble a second box-like frame that is just large enough to fit securely on the first frame but can be slid across that smaller frame. Don't add this frame to the projector yet.
Cut a plastic Fresnel lens down until you can fit it within your larger cardboard frame. The lens' original center must remain the center of the reduced lens.
Place the lens within a single cardboard piece that is the same width and height of the large frame. Tape this piece to the end of the large frame and place that frame onto the smaller frame that's taped to the player.
Turn the player on and point it toward a blank wall. Move the larger frame back and forth to focus the projected image. If the picture is upside down (due to the lens inverting it), turn the projector upside down.
Assemble a cardboard frame that is 45 cm long and the same height and width of an old TV set you have. Tape this frame to the TV screen, making sure no light escapes from any cracks in the frame.
Cut out another single cardboard piece the same size as the TV screen and cut a 19-cm hole in its center. Glue a Fresnel lens to this piece.
Secure the cardboard frame to the TV by running duct tape from the frame's end to the TV's top and bottom surfaces, then turn the set upside down. Please note that if the set hasn't been off for at least 12 hours, the picture may temporarily turn green or purple when you turn it on.
Place your lens piece inside the cardboard frame, placing it about midway through.
Turn the TV set upside down and have it face a blank wall. Turn off the lights and turn the TV on; the Fresnel lens inverts the image so the projection is right-side up. Adjust the TV's distance from the wall until you get the projection size you want, then adjust the lens' position in the frame until the picture is focused.
Connect a video player to the TV projector so you can play any videos on it you want.
Things You'll Need
MP4 player or TV set
VCR/DVD player (for TV)