
Projectors can be expensive. Fortunately, slide projectors are not. The idea has probably occurred to many of us that one of these could be melded with modern electronics. It’s possible it’s been done before, but This converted model, made at the Cairo Hackerspace (that’s Egypt, not Georgia), is the first working version that I’ve seen.
The linked Instructables article has a parts list, consisting of a specific projector, an LCD/TFT display, and a phone. It’s quick to note, however, that any similar parts should work for this surprisingly simple build. Author “ToutHackAmon” simply removed the back of an LCD screen, then replaced the film with it in the West German produced projector. The smartphone, a Nokia N900 in this case, was then used to generate video for everyone’s enjoyment.
This hack works because all LCD/TFT displays are apparently transparent (which I had no idea of). You normally can’t see through one only because of the housing on the back. It takes a little work to get this cover off, but once that’s done, there’s not much to setting up a projector like this. Although the reliability might be suspect, a backless LCD might also work well for a DIY heads-up display or something similar to Google Glass.
All lcd/tft displays are transmissive, meaning they depend on a backlight (nowadays mostly LED, but some are fluorescent). You could probably just put the whole display in there, although it would make a much dimmer display.
People have been using small LCD’s as the basis for video projectors for a long time. There’s even this cool magazine that had one as a cover project one time. I’ll bet you’ve heard of it, it’s called ‘Make’ (Volume 11) :-P
I’m embarrassed that I didn’t think of this. Now I’ll have to go to Goodwill tomorrow for a slide projector and then look to see if I have a spare LCD/TFT screen in my stash of salvaged parts.
If a slide projector is hard to find, you can also use an overhead projector as a light source/lens system.
I built one several years ago and it’s still going strong:
http://youtu.be/Xu-NispFLs8?t=1m22s