Home made projector!

[fearless joe]

this might be jumping the gun abit, but whent his is taken as far as it can go, and you move on, i sugest one of those complete diy projectors iv seen made out of a cold mirror, 2 frensnals and a triplate lense, you might want this, 1000watt metal halide,
http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW
maby thats a bit extrem, lol, but hay the next one could be a 'diy cinema'
joe

[Chernobyl]

Originally Posted by spanielgita

chernobyl - what can i say!!! you are the man!!!
that is some trully amazing results you got there!


where did you get that lighting kit from?
also, you seem to get alot of your screen to be displayed.

i was wondering what size your frensal lens was ????- i measured mines to be 27mm,
and my screen is 31, this means that i am losing 2cm from each side!

i am thinking of buying a frensal bigger lense, a 31cm to accomadate the whole screen,
but i have a few queries;

- if i put a bigger lense in will this distort the image?
- will i have to move my light source?

regards

Dan

Thanks Dan

I got the 250W lighting kit from Germany. I've put the link up for you
http://www.aoaforums.com/forum/72-links/
I want to try the 400W kit as this still wont scale much larger than the screen I have, so bear that in mind. Still no misgivings, its so good.
The 400W bulb may not have UVStop, so a UV filter may be required. Glass is quite a good UV filter, not sure if the OHP glass is enough though.

A number of things allow me to get more of the LCD onto the screen:
1) The nearer to the fresnel lense the LCD is, the more will fit on.
2) I cut away part of the OHPs casing that was blocking light from the edges of the fresnel lense.
3) The LCD has an option called 'clock' that literally shrinks the screen width.

I measured the Fresnel at 30.5cm width between outer rings.
If fitting a bigger fresnel you may need to do some work to make it fit. Make sure there is no OHP lid plastic blocking light to the LCD. You may need to cut some of the lid away carefully!
You may get away without having to adjust your bulb height. It should be easy anyway with the built in height adjuster I hope you have.
If you have no adjuster, it may be necessary to drop the light a little to allow the main light arc to spread over the whole of the fresnel. You will know more after trying.

A bigger lense shouldnt 'distort' the image but it will make the image slightly darker due to increased area for the light to hit. There are many grades of Fresnel lenses. Buy from a reputable place that can advice you on what to get.

Let me know what you decide on

[Chernobyl]

Originally Posted by fearless joe

this might be jumping the gun abit, but whent his is taken as far as it can go, and you move on, i sugest one of those complete diy projectors iv seen made out of a cold mirror, 2 frensnals and a triplate lense, you might want this, 1000watt metal halide,
http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW
maby thats a bit extrem, lol, but hay the next one could be a 'diy cinema'
joe

Hi Joe
Thats some light!
I think a Metal Halide 400W would easily be enough for me

If you do decide to give it a go, make sure the bulb has a CRI of >=85 or you get some funny colours and it has Daylight output (around 5200K).
You will need to change/remove the rear reflector. The spherical ones cost a lot of money as they go up in size. You may get away without using any reflector at all with that power, just fit the bulb and away you go! Not tremendously efficient but it could work well.

Lots of cooling and noise of the coolers need to be considered.
Even with a cold mirror, you need to shift a lot of heat out before it gets to the LCD.

Running costs are worth looking at too. Can you afford to run a 1KW fan heater most of the day (assuming its on that long)?

[Chernobyl]

I've lost quite a lot of photos of the bulb tranformation The 2 left you havent seen are below.

The first is of the bulb in place with some trusty balancers for the lense. These are for testing the height of the lense, something more secure will follow later.
The second picture is with the lense balanced in place. I have found that moving the lense around will shift the beam centre and allow you to relocate the beam.

The wiring from the OHP was used to hook everything up and was relatively simple.


I just tried a program out called ChrisTV. This is the perfect complement to the projector as it makes even bad analogue signals look watchable. It works with lots of Analogue and digital cards including my old WinTV FM which isnt on the list of supported hardware. Its a really professional piece of software.
I've never seen the WinTV card look so good!!

Photos of TV picture coming later, my Video Recorder (TV Tuner) decided to pack in as I got the camera out!

[Daniel ~]

I don't have a lot to say, but I keep coming back for more. Bravo to all of you, great work!

[Chernobyl]

Hi Daniel, thanks for your input and for watching

[Chernobyl]

I keep coming across items that would be very useful for the home made projector so decided to start a thread so should you find any products that may be a good buy you can let us know and hopefully get some feedback too.
These can be any products you have come across and not seen or tried but feel they could add value.

http://www.aoaforums.com/forum/showt...374#post300374

First on the list is a 15" LCD from Aria (UK). Its 16mS and costs £100 including VAT and delivery!

thanks to all contributors.

If you know a product is good and would like to recommend it, please post in the appropriate link or create a new one here
http://www.aoaforums.com/forum/forumdisplay.php?f=72

[Chernobyl]

At last here are photos of the projector in use as a Television using a WinTV FM analogue card and a video recorder as the TV tuner, linked by a SVHS cable.

Software used, WinTV driver for XP and ChrisTV application
Photos have been resized to 1024x768

[jcw122]

how are u guys getting such nice pics while gaming? what is the response time of those LCD's? anyone got ghosting?

[Chernobyl]

Hi JCW
you hit one of my issues too. Its very hard to get a decent picture of anything moving.
I keep taking photos and select the few that look ok at the end. Sometimes I dont get any good photos.

The response time of my LCD (iiyama E380S) is 15 or 16mS depending where you read.
I find it superb for games though a friend who plays counterstrike says its not quite as fast as a CRT monitor (He still plays it for hours though ).


As I'm here I'll pass on the latest findings:

I've used the new Metal Halide bulb for a while now and decided to play with the rear reflector/bulb distances from each other out of curiosity.
From reading on the web, the filament of the bulb should be placed at the focal point of the rear semi sphere reflector. This bulb doesnt have a small filament, it has a rather larger bulbous light source and blocks reflected light a lot more than a filament.
After lowering the reflector to increase the distance between it and the bulb, the result is a brighter picture I wont try to demonstrate on camera as it auto adjusts for brightness anyway.

So it seems having the bulb a little further from the focal point helps get more light to the screen.

Oh yes, I tried the 3M 1750 OHP's original rear reflector lense which is much smaller than the one bought with the new bulb kit. The result was a noticeable drop in light output. Its worth getting one of those bigger rear reflectors if fitting a MH bulb.


I've just finished playing Chronicles of Riddick and it looks amazing. This project is worth every penny spent

[flibble]

I just found this thread, hopefully not everyone has packed up and gone home;p

I also saw the thg guide, and used it to make an lcd projector. The final result is ok, although less than optimal.

The screen we got, a compaq TFT 450 15" LCD was about £50, minus psu which we made from a computer PSU (these screens have funny ps2(mini-dimm) style power connectors. The screen looked ok for our intended use (mostly movies), but turned out to have a largeish control board which wired into the screen with 4 very short ribbons, two per side, for a third of the way along the widest sides:/ Not having the ability to send back the lcd's, or the resources to buy a new one, we set the monitor to 800x600 and moved the displayed image as far left as possible. This works reasonably well, no visable pixelation although the far left and right bits of the screen arent viewable (about 10%). The pc its running off has a matrox g400 in it, so software screen shifting isnt really an option.

The projector was an 'Elite vision' ohp with a 250w halogen bulb. Sadly, we bought it without knowing the bulb's wattage, although there wasnt anything good/reasonable on ebay at the time.

We bought a screen from ebay too, not sure of the brightness, I'd guess at maybe 1.1 or 1.2.

Overall, the project has been fairly successful, but luck hasnt been on our side all that much. I'm weighing up the idea of improving it, either with a better screen with a less restrictive ribbon placement, a 400w ohp from ebay, or perhaps replacing the light fitting with a more powerful metal halide lamp, as you did, Chernobyl. I've got a couple of questions about the light though:

Is having a triplet lense system in your ohp essential or just really useful if you wish to use another type of bulb? I seem to remember there being a lense above the bulb in ours, but I'm not sure and its not straight forward to check.

How easy is it to modify an ohp to fit the bulb? I dont really have much in the way of tools, but i can normally find a way to do what i need. What did you have to do to fit the metal halide lamp?

Thanks so much
Dan

[Chernobyl]

Originally Posted by flibble

I just found this thread, hopefully not everyone has packed up and gone home;p

I also saw the thg guide, and used it to make an lcd projector. The final result is ok, although less than optimal.

The screen we got, a compaq TFT 450 15" LCD was about £50, minus psu which we made from a computer PSU (these screens have funny ps2(mini-dimm) style power connectors. The screen looked ok for our intended use (mostly movies), but turned out to have a largeish control board which wired into the screen with 4 very short ribbons, two per side, for a third of the way along the widest sides:/ Not having the ability to send back the lcd's, or the resources to buy a new one, we set the monitor to 800x600 and moved the displayed image as far left as possible. This works reasonably well, no visable pixelation although the far left and right bits of the screen arent viewable (about 10%). The pc its running off has a matrox g400 in it, so software screen shifting isnt really an option.

The projector was an 'Elite vision' ohp with a 250w halogen bulb. Sadly, we bought it without knowing the bulb's wattage, although there wasnt anything good/reasonable on ebay at the time.

We bought a screen from ebay too, not sure of the brightness, I'd guess at maybe 1.1 or 1.2.

Overall, the project has been fairly successful, but luck hasnt been on our side all that much. I'm weighing up the idea of improving it, either with a better screen with a less restrictive ribbon placement, a 400w ohp from ebay, or perhaps replacing the light fitting with a more powerful metal halide lamp, as you did, Chernobyl. I've got a couple of questions about the light though:

Is having a triplet lense system in your ohp essential or just really useful if you wish to use another type of bulb? I seem to remember there being a lense above the bulb in ours, but I'm not sure and its not straight forward to check.

How easy is it to modify an ohp to fit the bulb? I dont really have much in the way of tools, but i can normally find a way to do what i need. What did you have to do to fit the metal halide lamp?

Thanks so much
Dan

Hi Dan
Yeah, I'm still around if you want assistance
If you need piccys of anything let me know.
Glad you managed to get the project off the ground despite your setbacks.

The triplet lense (edit: this is the Condensor lense not the triplet) is not essential but I do recommend it strongly.
Having a large lense above the bulb catches more of the light that would not hit the Fresnel/LCD. It also spreads the light more evenly across the display area.
Without the lense, you still get a useable picture but it is noticably brighter in the centre / darker in the corners.

The lense you have above the bulb is the one that makes it a triplet lense system (edit: again, this is the condensor lense, not the triplet).
Fitting a new bulb will be a different challenge in each different OHP.
The principle should remain the same, so I'll describe as best I can.

When you get the new bulb, get a bigger rear reflector for it as well.
The one supplied with my OHP was small and gave a poor result, luckily I bought a replacement in case it was needed.

Hopefully your OHP has lever/knob which raises/lowers the bulb to balance colour across the whole screen. The platform the bulb is on will move up and down.
I highly recommend keeping this platform and the lever working. Mount the new bulb on the platform, this will allow you to easily select the height the new bulb will need to be.
If your platform isnt adjustable, you made need to unmount it and make your own height adjuster for it.

I had to remove the entire height adjuster frame and hammer the bulb platform flat using wood and a rubber mallet so the new bulb would fit on it.
The metal platform was placed on an old wooden shelf to protect it and my floor! The flattening was performed by holding a piece of wood on the area to be flattened and hitting that with the rubber mallet many times very hard.
It doesnt need to be perfect, as long as the bulb can be mounted on it.
If your platform is too small to mount the new bulb you will need to extend it.
Drill holes at the mount points for the bulb


Once your platform is ready for the new bulb you need to place the rear reflector, bulb and lense. The distances between them will determine how efficiently the light is forwarded to the LCD.

The focal point of the rear reflector is the 'recommended' place to put the bulb. I found moving the bulb a little further away allows more light to reflect past the bulb onto the lense. You will need to see what works best.
To find the focal point, look into the lense and move a finger back/forward until the reflection of your finger is the same size as your finger. place the bottom edge of the bulb at that height or slightly further away.

The lense on top needs to be close to the bulb to catch as much light as possible, but not so close it impedes airflow round the bulb.

As you can see its not quite straightforward to find the right heights so you may want to make an adjustable mount for the lense. The light can be raised/lowered easily enough with washers etc and the reflector should remain static on the shelf.

Mine is shockingly put together using lots of tin foil moulded into mounts for the lense. This allowed me to raise/squash it very easily to get the heights. Its worked so well, I've left it like that. Someday soon I'll finish the job


The new 250W bulb is brilliant as it is as bright as the old 400W and whites are even brighter. It also runs much much cooler and should be cooler than your 250W halogen.
I removed the OHP glass to get a bit more light as the bulb doesnt produce much UV light. (edit: dont do this, it disturbs air flow in the OHP and probably isnt good for the LCD)
I'd really like to make the screen much bigger than 5ft. Mine should do 6ft easily, but I would recommend a 400W bulb if going bigger (edit: a decent screen is good enough for nearly a 3 metre screen with a 250W MH bulb).
The 400W dont have UVstop at the moment (even when advertised that they do!), so you must use UV protection of some sort. The OHP glass may be good enough for the job?

Your OHP should be fine with a 400W MH bulb as it can remove the heat from a hotter 250W Halogen effectively.

Good luck, keep us informed if you have the time
If you need help, especially with bulb selection, do ask.

[Chernobyl]

Hi everyone
its time for a poll !

I intended on writing up a full article on making your own Projector.
There doesnt appear to be a lot of interest so am wondering if it is worth while my spending time on it.

If there is enough support, I will surely write one, its your call
Please post here with your preference.

Thanks

[fearless joe]

hay, im obviously gona say yes, if you want help im sure it could be a group effort,. the only reason i havnt done min yet is cos iv been so busy with uni work.

If you wanted a 3d animation done showing all the bits going togeter i could make one. i spend like 5 hours a day doing 3d for uni anyway i might as well do something thats gona be used lol.
up to you
joe

[dolanenwindrift]

Write the article!

[danrok]

Sounds like a good idea!

[Pitch]

I agree, go for it my friend!

[Gizmo]

By all means, write it up! I'm sure someone on Staff will even be willing to offer assistance, if you want it.

[Pitch]

Here's a little more insentive:

http://www.google.co.uk/search?num=5...jector&spell=1

[flibble]

Thanks Chenobyl A very informative and helpfull reply. I'll try and make sure I've got a triplet lense and see if I can obtain one of them there bulb kits. That german distributor you mention does seem to be out of stock though. However, he does do UV shield glass, so I guess if the 400w bulb came in, I could proberly get that and the glass supposedly certified to shield UV.