Converting Transparency Sheets To An LCD Monitor

Apparently, there’s some sort of sporting event being televised this weekend that has been historically used as an excuse to buy a big-screen TV. [Joel] wanted a huge-screen TV on the cheap, so he converted an overhead projector to something he can use with his XBox.

Using a bare LCD panel with an overhead projector is a decades-old hack we’ve covered before. The basic idea is fairly simple, but we’ve never seen anything that could be considered a semi-permanent build. [Joel] started his project by picking up a surplus overhead projector for $25 and routing a cutting board to mount the LCD in. The bulb in the projector added a lot of heat, so three small fans are used to blow air between the projector glass and the LCD display.

[Joel] started off looking at the LumenLab DIY projector project, but considered that to be a terrible amount of work with a fairly high initial investment. If you don’t count the few LCDs [Joel] burned through while building his project, his projector was built for under $100. We’re loving the result and are sure it will be much appreciated at [Joel]’s LAN parties.

37 thoughts on “Converting Transparency Sheets To An LCD Monitor

  1. I think, could be wrong, but I think there was a piece of somthing that looked like thick glass in old Kodak slide projectors. The purpose? To reduce the amount of heat getting to the plastic slide. Well, that’s the way I heard it. I don’t recall such a device in an overhead projector. Maybe that would help w/the heat problem.

  2. A similar project was done years ago and was featured on Tom’s Hardware site. I’ll find the link if it is still availabla. I have the video (Star Trek) still on my computer.

  3. With the rate at which they sell high res phones/pads today, paired with the price fall of high power leds, I believe in a matter of a couple years the surplus market will be flooded with cheap
    parts useable to build much smaller projectors.
    Cool hack though!

  4. I tried buying a small projector recently, best I could get was a used pico-projector for about £80 (a one-off auction).

    I did also try to make the LCD projector system once before, it went fine up until I had to get all the control boards hooked up to each other and the LCD panel. The manufacturer didn’t allow any slack so I had to solder 40-ish tiny cables into tiny connectors, rest assured that did not go well.

    Honestly I think I’d rather be lazy than hacky for projectors mostly because I can’t find a suitable 1080p yet physically small panel. A laptop’s display would do well but they’re hard to control.

  5. If I recall correctly used to have a whole section dedicated to this kind of malarkey. I’d check only I’m surfing on edge at the minute. Used to be the primary non playstation use of psone screens.

    @campgareth check out eBay for lvds controllers. If you have a spare laptop screen lying around £25 could buy you VGA/composite/hdmi controller board.

    1. I did a little research on that, but ended up going with the HDTV because I figured it would be cheaper in the end (and it was). Laptop screens are pretty plentiful though. LVDS controllers would be a great way to keep them out of landfills. I also want to research smaller screens for building compact projectors, like Qwerty suggests. There’s gotta be a way to control those little guys.

  6. Very nicely done, I like the custom LCD holder with cooling fans.

    I’ve got an old LumenLab build that I rushed so things didn’t work out so great, it did run but I could never get it to focus completely, the size of the box is like a small coffin and the heat generated from the huge 400watt bulb was quite something.
    I do have an old OHP in the attic I’ve been meaning to get round to doing something with, perhaps steal the 15″ screen from the ‘failed’ LumenLab build…

    In the meantime I recently got a MicroVision ShowWX pico projector, it’s very very cool for the size & price, laser light powered so always in focus and playing films through the VGA connection I increase the sharpness on the software player a little and the end result is very good. Only major drawback is you need a completely dark room to get the most out of it when it’s projected 6 foot wide.
    Looking forward to the next laser pico projector from MicroVision, if what I’ve read is true then it’ll be 720p and 3D capable through passive polarisation!

  7. During the build of my Multitouch I used a thick piece of glass that had a slight tint between the projector and the acrylic surface to absorb heat from the projector bulb. This worked well to avoid the warping of the acrylic.

  8. This is so 2003…I built one back then, when projectors were actually still expensive. I started with an LCD that already had a TV tuner in it. Made a wooden box, mounted a Lumenlab lens, got a huge HID metal-halide lamp, etc.

    Used it for a couple years, and then computer projectors dropped below $400. I don’t think there’s any reason to build your own projector these days, other than an extreme emergency hack. These projectors are very, very dim compared to cheap DLP commercial models. The brightness was also uneven; noticeably dimmer at the edges. Also: bulky and hot.

      1. Trololololololololololool! Trololololollllll!

        But seriously man, I’d never claim that this is anything close to a DLP projector. It’s inferior in every way, except that it was only $73, all-inclusive. I will also argue that it produces no more heat than a DLP projector, but of course it is bulkier. Still not bad IMHO. Mostly just for the fun of it!

      2. Not trolling, just making sure no one else actually does this hoping it’s going to be awesome :)

        And it’s not really that creative (other than the arguably slick CNC interpretation), since it’s been done to death nearly a decade ago and commercial versions of the same thing were standard a decade before that. It is a great emergency hack. It is not a good cost/result ratio.

    1. LOL I fking love some of these people. They come on here, sh1t on a project they SWEAR they’ve done before and that theirs was better.

      yet provides no pictures or any technical basis to make anyone believe that he isn’t full of sh1t. sure thing buddy, I bet you made this in 2003 and it was better (makes jerk0ff motion).

      BTW if your going to shit on a project, at least do it to some stupid adrunio one, or that silly clock with the folding paper hands.

  9. I like these overhead projector hacks and this is the best I’ve seen so far.

    But I think DIY projection doesn’t have a very bright future. The problem is the lack of devices to scavenge fitting light sources from.

    Small size HD LCDs will be easy to find as people replace their smartphone/tablet often. But there are no dirt cheap light sources with a size that fits the screens.

    And buying new light components will bring the DIY path too close in price to a retail projector to be worth it I’d think. Prices for decent HD pico projectors will likely plummet in the next few years.

  10. Twenty five odd years ago my phD supervisor bought a commercial model very similar to this build – even down to the fans – it was CGA though :-) — and sat atop tha OHP. LCDs of the day were too slow to show video, but it was cutting edge for its time. Hard to believe there was actually a market for something like that eh?
    Nice work!

    1. We had one just about like it too in AutoCad class (1990). The professor could use it to show the whole class what was on the screen. Worked well in that situation at that time.

      I had looked into doing this at one time, but the overhead projector I had seemed awfully loud. The fans in the projectors we had were way quieter.

    1. agreed. the title for this is horrible and honestly if it weren’t for the picture i wouldn’t have click.

      Glad I did though because the guy did a nice job. I’m guessing it’s the clowns at hack-a-whatever, not the creator.

  11. I see that the halogen or High Pressure Na lamps will generate heat in a normal overhead projector produc.; My question is; Would high power CREE or other mfr LED elements in a matrix provide enough lumens as a substitute but with reduced heat generation? Perhaps DLP products will drop so far in price in future, much like LCD and LED TVs dove in price recently (throwing many of my friends @ panasonic out of work…)

    1. The problem with a matrix of LEDs is, the light source in a projector needs to be, effectively, a single point source. Projectors use lenses to compensate for this, but even then the bulbs have to give a small area of light.

      With a matrix of, say, 9 LEDs, you’d essentially have 9 dim projectors, all projecting images off-centre and overlapping each other. It’d look like a bad Andy Warhol painting.

  12. So where are the project details. I can only see a couple of paragraphs about how [Joel] (what’s with the square brackets?) made something, and one tiny picture of who knows what.

      1. No offense, but, “Decades Old”?
        The first overhead LCD anything I saw was a b/w panel for a Ti Calculator that was new in the 1990’s, the next time I saw anything like that was in 2004 when I was sourcing parts to do it myself and found an article where in some one had finally done/posted it just a month earlier. (I had tried sourcing parts for such a build since about 1997 when I first saw the Ti panel and thought “I will do this, with a real LCD” but back then LCD’s of 800×600 resolution were over $4,000, so I didn’t.)

        Anyway… I feel kind of like a jerk for calling this, but “decades old” build is a stretch. “More than a Decade Old Build” makes sense.

  13. i was thinking about the possibilty to use a ordinary slides projector modified to a lo-fi video projector?
    does anybody know if there are suitable lcds or other display technology screens avaliable (or will be avaliable in future) – black level, contrast, heat,…?
    slide projectors are still good and powerful light sources with a wide range of hq lenses, and it is only just a matter of time imo when it is easy possible to to put a digital slide into like a classic slide – so do not throw you slide projector away ;-)

    1. Seems like you could use the display from an old digital camera or other portable device, assuming that the backlight layer and LCD layers are possible to separate. Then, you’d just have to figure out a controller board, which has been done here on Hack a Day.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.