Thursday, February 16, 2006

DIY Projector

I wanted a projector for my room at home instead of my tv. A cheap projector would cost at least $800 so I inquired about building one. About a year ago I ordered the "ebay build your own 150" projector from a old tv kit" for $6. It offered links to instructions and shipped a flimsy fresnel lens. I tried it with an extra CRT monitor. The fresnel flips and inverts the image so i turned the monitor upside down. (If you turn it on then flip it it can turn the screen green) The image is still backwards but you can't tell during movies, just viewing text. It was very dim even in a completely dark room so it was pointless compared to my tv. My brother later started to play with it on a extra tv. He built a box to hold the lens and we got other test fresnel lenses from office supply stores. His current design works well in a dark room for a few foot sized image on the wall with two lenses in it.
Now my college apartment has a large wall that I knew would be perfect for a projector. My friend Garret let me know about I planned and budgeted to build one of their kits for about $300. I ordered a used 15" LCD monitor from ebay first. Then Garrett gave me his projector project parts which had a power supply malfunction. I retrieved the extra fresnel lenses from my brother including a 12" fresnel lens I've had since I was about 12 from LCD was easy to take apart.

The LCD has its electronics behind the backlight. It is attached with ribbon cable so it was rotated at a 90 degree angle. The LCD case itself and another metal panel in it served to make a box. Inside the box is the overhead projector mount and bulb from Garrett. These bulbs get very hot so I just put the bedroom fan on it and covered it with some shirts so the roommates aren't blinded.

Using the 12" fresnel and the 6" fresnel from ebay I got a image on a pizza box. I secured the LCD box to the side of a unused PC server and duct taped it to a table. The fan sits on a box and is covered by temporary cardboard; a pizza box and IST school poster project from last semester. The front ebay lens focuses the image so it rests on a box and K'nex.

After a short run time it smelled like burning. The bulb has a polarized piece of glass in front of it to create polarized light for the LCD. The wood the bulb was mounted to was recieving half of the reflected light causing it to smoke. I mounted the bulb to a bad PC psu (power supply) box with the guts taken out.

The LCD can only recieve vga video signal from a PC or laptop so I made a left and right audio cable from old headphones, rca jacks. and lamp wire.

The duct tape projector survived Saw II and Back to the future I and II movies. Then it was dismantled and rebuilt using wiring to hold it together and fitted cardboard replacing the LCD casing, pizza, and poster boards.

The bulb cracked while being mounted but it is inexpensively replaced. Total cost: ebay used LCD, ebay fresnel, new roll of duct tape, new power strip, female to female vga adapter, and free parts from friend = $120.

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