Projectors are getting a lot less expensive these days, what with China pumping out Pico projectors by the boat load and all. But did you know it’s not that hard to convert an old slide projector to digital? [Alec Smecher] shows us how with a 1950’s LaBelle 75 slide projector, and the result is pretty awesome.
Digital projectors can use a few different technologies to work. The best, and brightest is DLP (Digital Light Processing) by Texas Instruments — which is pretty well the world-wide standard for high-end, high-lumen digital projection. It works by bouncing red, green, and blue light off of three DMD’s (Digital Micromirror Devices) which have an array of tiny 2-position mirrors, with each representing a pixel.
One of the older technologies is LCD, which is even easier to understand. You shine white light through a color LCD, and there is your projection. All you need for a projector, then, is an LCD, a light source, and a bit of optics.
Since the slide projector already has the optics in place, doing a conversion like this is as simple as replacing the slide holder with an LCD (you’ll have to remove the back light to make it transparent), and if you want, upgrading the expensive lamp to LED.
[Alec] is using a 2.2″ LCD, a Raspberry Pi to feed a video signal to it, and a 10W LED to power the entire thing. Since all those components are pretty small, it wasn’t hard to fit everything inside the original projector’s casing. Unfortunately the LCD he’s using only has a resolution of 320 x 240, though we imagine he could upgrade it if he wants to.
Regardless of the resolution, the end result is a gorgeous antique projector, with a digital twist.
We’ve shared lots of DIY Projector builds over the years. And if you’re looking for a higher resolution build, just use a desktop LCD!
20 thoughts on “Vintage Video Projector Lives Again”
Imagry a little misleading as I was expecting an epic DLP hack. this is otherwise ‘Meh.’
The only real downfall of this is that it’s really difficult to find small, high resolution LCD panels.
Unfortunately, 320×240 doesn’t look anywhere near as good in real life as it does in a youtube video.
It’s not going to replace my other projector (which is itself a teenager) but it actually looks pretty good.
The display is the easy part (replacement for better cell phones), connecting to it is the hard one…
Well, enter cheap tablets from china and you can have over FHD for under 20€, the backlight is held with drops of glue and some hope, so to remove them is very, very, very easy.
Even phablet displays are big and have nice resolution.
At a local university surplus clearing house I saw some old projectors and thought the same thing but would have gone with a cheap and small LCD projector and taken it apart for parts.
However, this way is much cheaper.
I’ve been thinking of this too, but also keeping the film reels in place as an aesthetic, motorizing them to appear to be utilized – maybe even jittering a bit of film as if it were being taking in…
Oh! And add a random vertical line (film scratch) every now and then. B^)
And don’t forget the occasional ‘jam’ followed by the ‘frame’ melting away :-)
Usually there is only one DMD micromirrors chip illuminated by an alternating RGB colour source.
Or, in the non-LED versions, a big honking lamp and a spinning filter wheel.
I was referring mostly to high-end cinema projectors, which all use individual DMDs for each red, blue, and green light source. Not sure you can get 240hz in 3 colors out of 1 DMD…
I have a Toshiba TLP-770. $9,000 projector, in 1999. I paid $10. 1024×768. I’d like to write a remote control program for it via its RS232 port. The manual has all the control codes.
It uses three separate LCDs and color filters, with a single halogen parabolic reflector lamp. Changing that out for LED would be very nice, have to figure out how to defeat the bulb detection, startup and frigging high power supply to it.
My other projector is a Sony from about the same era, with the name of a local elementary school engraved into it, purchased for maybe $40. Still works great, but you sure can see how much LCD contrast has improved since then.
“The best, and brightest is DLP”
Ill disagree with that one. I never want a DLP again, at least not a single dlp with a color wheel. I miss my 3LCD projector. I actually had the color wheel explode in mine, lucky it was still in warranty.
Im waiting for true laser projection, Compound Photonics is supposed to be coming out with a very reasonably priced 4k projector pretty soon.
Still the brightest… you simply can’t put high lumens through an LCD or three without having them burn up. Also a lot of the companies making laser projectors are cheating and still use DMDs, but with laser as the light source.
The LCoS projectors are very bright too.
It would’ve been nice if a better LCD was used. 320×240 resolution is almost unusable for a projector.
yet another raspberry pi case
I think what you mean is SMSHD: “Somebody Made Something, How Dreary”.
Any post tagged with Raspberry Pi should get an automatic “YARPC” first post. That would free up Feena for other hobbies.
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