After looking at commercial projectors for some time, i restumbled across the world of DIY projectors (I had investigated this a few years ago but did go anywhere). After completeing a few other DIY projects including a theatre/disco style dimmer pack I decided to give this a go. For the fun of making it as well as the final result.

At the moment I am costing and sourcing everything. I may be able to get a free 17" screen which, if it works will be a great money saver. i have also found a 400W bulb for £10 . The next step is the fresnels and projection lens. Due to my limited budget, I am trying to source the cheapest set of 17" compatable lenses possible. Preferrably within the UK to keep postage costs down. Does anyone have any ideas?

Just the good ol' sources like craigslist, ebay, and office/college surplusers. Start there, and keep an eye for parts at street markets and garage sales. although fresnals and lenses are more often found online.

Due to the budget nature of my projector I have now decided that using an old ohp (which I may be able to get fomr my school for free as they are upgrading to digital projectors). As a base. Because all the lenses will already be there, my pocket will be pleased

I was thinking of using the LCD with the existing bulb at first to see how bright it would be but if that isnt bright enough, I am considering keeping the OHP base but stripping out the bulb assembly (perhaps leaving the fans and switches) and installing my own MH bulb. And, if i get this working, I may build up a case around the top part of the OHP to make it more subtle.

Depending on which type of overhead projector I get will possibly decide the design. Some use a mirror at the top to direct the light fomr vertically to horizontally. One thought that occurred to me is that if this mirror was removed, the OHP could be tiled on its side and used horizontally... Juts a though. Otherwise I will juts make it an upright.

These are a few of my initial sketches of the design (the 1st showing the 2 possible paths of the light depending on the presence of a mirror).

Asked at my school and i turns out i may be able to get an old laptop and OHP for free . I can juts use the laptop as the controller then, give it wireless and stream over the network. And juts think how much a wireless projector costs commercially!!!

This means I will only have to buy the bulb, ballast and possibly the reflector and a fan.

I think this means I will onyl need to spend less than £50 on it (excluding the case if i add one).

£25 - bulb
£20 - ballast, ignitor and cap


A HUGE bonus as im never one for spending lots of money.

One thing about using a laptop LCD is that most of the time they have FCC issues. I know my Dell Inspiron 3800 had insane FCC issues when I pulled it apart. Just be aware that you might run into that. Looking forward to seeing what you can do. Good luck!

Ok. Thanks for the heads up. The school technitian seemed to think that they have a whole cupboard of old laptops with various problems so I if i completely screw one up, im sure there will be more I can scrounge

I now have the laptop from school and am going to start stripping the screen down asap.
It is a Toshiba Satellite Pro that was 5 years old so had come to the end of its 5 year cycle at school.

Tomorrow im going to ask aorund and hopefully come home with an OHP.

[pics to follow]

I have got as far as i can with the screen stripping. I have taken the cover and supports off so it is now juts the LCD and backlight module. However to get the baclight and circuit board off i need REALLY small screwdrivers so I guess the process will have to wait till tomorrow when i can get some.

Here are the pictures of it in various stages of stripping.

Just a tip when buying very small screw drivers- The cheap ones suck. Spend a few more bucks and get some that will not just round off after the first use. By that I mean that the cheap ones are made form very weak steel, and will fail under normal use. Just go get some craftsman, or other good drivers. You will think yourself in the years to come.

I have found an old OHP lurking in the RE department and the teacher has said sh doesnt use it because one of the lenses has fallen out (its still there so easily fixable). Shes going to talk to the bursar and hopefully I will get it tomorrow and can get some form of projected image this weekend

Ive got the screwedriver i needed and have extracted the LCD from the screen . Really pleased that ive got this far. No issues with cables. I unplugged the LCD's data cable before stripping and then plugged it back in once the backlight was removed.

What do you normally do with the backlight? Should i unplug the connector before or after the controller?

YAY!!!! I have, just this second managed to get my hands on an old ohp from school. It is an 'Elite Optics Viewrite II". It has a working bulb and seems to project a crisp image. The front lens of the 90 degree objective block has come out but resting it ontop of the bottom lens, i can get a clear picture. Photos and diagrams to follow. Hopefully ill get my first projected image this weekend. And cost so far: NOTHING!!!

Words cant describe the feeling when you get an image to display on YOUR projector that YOU have made (even only a laptop-OHP make)!!!

When i get some pics ill upload them

EDIT: Some very quick "wow it works" pics. Ill finetune it in toe morning and get some more decent ones.

http://www.sharemation.com:80/minimini/pjworking1.jpg
http://www.sharemation.com:80/minimini/pjworking2.jpg

It's a kind of pride that puffs up your chest and nearly brings a tear to your eye.

Have managed to sort out blurriness (lens had fallen out ), connect laptop to network and ifnd a great place to proejct form and to.

Still to do:
test network film streaming
Test my video card with external inputs
Put a thermometer between the LCD and OHP to test the termperature over a long run

Problems encountered so far:
While the image is crisp, it is crisper in the middle than the edges (or t'other way round depending on how i focus it). Is this something im just going ot have to live with or is there a solution?

The fan is quite noisy but i dont think i can do anything about this without completely blocking off the cooling which is not a wise idea. In the long term i may open the OHP up and see if i can replace it. Perhaps if/when i have to replace the bulb. When that decision comes along i will have to choose betwene another OHP bulb or a MH.

Pics to come...

Juts stuck a thermometer probe under the LCD. Was getting to above 100 degees F so i turned it off. Now going to try raising the LCD up off the OHP more. IF that fails then i may need extra cooling.

Raised LCD off OHP and it heated slower but was still going to overheat. Current setup uses my desk fan. This managses to keep it steady around 70 degrees . This will do for now but next time i see one, ill get a proper fan for airflow. Not sure where ill power it form yet thugh. Might wire up 2 usb ports to get 10V for it.


EDIT: Some pics of the Warner Bros logo taken with 2 different settings on my camera. The width of that picture is about 6ft

http://www.sharemation.com:80/minimini/warner1.JPG
http://www.sharemation.com:80/minimini/warner2.JPG

Just use two smaller fans and wire them to the 5 volts from the usb. A 50mm fan will run quite well on 5 volts.

But I do like your idea of bridging the ports. Let us know how that goes. I would love to see how it works!

I have ordered 3 CPU fans (if i dont use them all, then im sure ill find a use for them). Im going to mount these in place of the desk fan on boxes im currently using. I also plam to make some brackets for the laptop and some raised platform edges for the LCD to sit on.

Current setup: http://www.sharemation.com:80/minimini/pj1.JPG (rather Heath Robinson )

Looks good. I like the red. Are you gonna stick with that for the paint scheme?

i hadnt really considered the colour scheme. At the moment making sure it it is all held together is my main priority. Ill probably paint it black if i do. Perhaps some red go faster stripes or flames would look good.

Thinking about it again, black with flames would look really cool.

Here you go. I got bored waiting for a friend to show up. LOL

Nice!!! Not sure if ill go for blue flames or red. Or if im going to box in the gap between the head and the base or not. Would look a bit like a giant metranome if it did but would reduce lght leakage.

Today ive been planning on how i can make my projector a more permentant unit. Im going to make and add a slot to slide the LCD into, a shelf for the laptop and a mount fo the fan (s).

3 diagrams of the shelf assembly and one of the slot are shown.

Days are never long enough... Unfortunately due to other factors like a big school production for which I am lighting, other DIY projects and juts not enough time, my proejctor will have to go on hold for a while. I may get round to laser cutting the odd bit of plastic when im in DT at school but otherwise it looks like it will have to remain where it is until nearer christmas/after christmas . This annoys me as i SO want to get on with it and seeing it working just makes the finished result seem oven closer! I also want to watch films on it over christmas. Perhaps if i get all the bits cut, i can attach them all over half term.

Damn, sorry to hear about your time problem. If only you could get hold of that watch Huey, Dewey, and Louie had on Duck Tails. You could get it done in a flash.

Not posted for a while so i thought i'd give a progress report.

Managed to make some cardboard mockups of the fan mounts and the LCD supports. These just about work if retaped to the OHP every use and last Sunday I watched Hot Fuzz on it with some new speakers (inc a subwoofer) and a 5.1 sound card (sounds great!). Picture is fine in absolute darkness however yesterday while watching Ocean's 13, i noticed the brightness dropping off at the top of the screen. I have yet to investigate the cause. I am just hoping that it isnt to do with the fact that that is the warmest part of the screen (furthest ftrom the fans) but I didnt notice any browning to it may just be uneven distribution by the ohp. Once i have a more permeanant installation of the fans and LCD I think I will polish the screen to increase the brightness.

Something I didnt count on was the amount of light spillage coming from around the ohp fresnel lens. I have taped cardboard over these gaps and fortunately the PJ can sit on the windowsill very nicely with the curtains nearly fully closed and pinned together at the top and bottom. This means that only the light from the top lens can actually escape into the room.

I havent got any pictures but next time I watch something ill get some to upload.