This is a blast from the past! Around 2003 (wow, 10 years ago!) I decided to build a quick and dirty projector because I wanted to watch movies on the big screen. I recently stumbled upon the pictures which were taken with my 0.2 MegaPixel camera. This project is still quite relevant today as the brightness is far superior to anything else you’ll be able to buy for the cost of a broken LCD screen and an old overhead projector.
The general idea is to lay an LCD panel on the glass of an overhead projector.
2nd hand overhead projector: $50
2nd hand LCD screen with broken backlight: $20
Strong cloth tape, screwdrivers, computer case fan or something similar, cardboard.
Take the LCD screen apart, be very gentle because you don’t want to destroy the panel, they are quite weak. You need to separate the panel from the backlight module so that light from the projector can go through the LCD panel. Every screen is different and this can be quite complicated, patience and a light touch are the keys to success.
You’ll need to keep the control module intact, and there will be a cable from the LCD panel to the control module. This cable is normally a flat ribbon type of cable and extremely delicate so be very careful. Once you have the whole thing apart, it’s time to position it on the overhead projector’s glass bed. The cable connecting the panel to the control module might get in the way here, you’ll need to work some manipulative magic and make it as unobtrusive as possible.
The most important point here is that the overhead projector will get hot, and this will cause the LCD to lose it’s colour. Not permanently, but it probably won’t last more than 10 minutes before you have to turn it off to cool down unless you do something about it. What I did was raise the LCD panel above the glass bed of the overhead projector. The gap on mine was around 5 mm. I used cardboard to do this. I then used a computer fan to pump air through the space between the glass and the LCD panel. You’ll probably want to roll up some paper to make some ducting for the fan, directing the flow between the LCD panel and the glass. Seal the edges around the panel with some tape and leave only enough space for the airflow input and output, this is so that the air is forced to flow through the whole section before it exits. I found it worked best to put the input and output on the same side but as far away from each other as possible – it’s no good having the air flow from one side straight to the other and only cover a small area, it needs to flow through the whole thing.
Finally, try to black out all of the light coming from underneath the glass of the overhead projector, the only light allowed through should be the light that goes directly through the LCD. It’s also much better if you put some blackout plastic around the whole projector to stop unwanted light from escaping.