Read alot of posts, am i going in the right direction?

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I generally have alot of questions to go with this i am sorry, i'm hoping someone more to clarify what i know, i really have tried hard to understand everything but i am totally new, i don't have any electronics background but i will be buying a book soon. I apologise in advance if their is anything i have missed in the forums which could help answer one of my questions.

I would like a very simple overhead projector combined with a lcd panel removed from a tft monitor between 10 and (like everyone) 15 inches.

First of all an OHP projector with over 4000 lumens is a tall order to get hold off as new they generally start off at £300 and they are pretty scarce on UK Ebay. I don't know a huge amount about projectors (it will become ever more inscreasingly obvious) I wondered if you can swap the bulbs of projectors but if it was a easy as buying a cheap projector and replacing it with a high powered bulb wouldn't everyone do it?
If you swap different power bulbs i.e. a 250w to a 400w if someone could just clarify to me why is this not possible if it is because the fan can't cope with the extra heat or if the bulb fixture inside the projector simply isnt designed for it and won't take it?
I saw a thread about modifying OHPs and it seems quite hard (and dangerous). What are ballasts and ignitors?
Also just wondering so i know, what is the deal with halogen bulbs and metal halide bulbs being swapped in the same projector?
Many websites don't list if the projector uses a halogen bulb or MH bulb so can you tell by the voltage or simply the watts?
I hear about some OHPs can sometimes shine more bright in the middle of the image in the wall and that 'triplet lens' type
is best could someone show me a picture so i know what i am looking for?
Also I hear that a 15" screen might get cut off very slightly
is there a general size on all projectors or is this only on some projectors?

to see if i'm heading in the right direction i looked up projectors to buy and found this:
http://www.aandcaudio.co.uk/3M_1850_OHP_Overhead_Projector_pid1809.htm

would this be good?

The LCD Panel
For stripping a TFT monitor i have read some threads about it but i was wondering if there is a really concise guide?
I see some monitors are harder to strip than others, there has been a thread about which are best but it is hard to match a
monitor you have found to one someone has tried before, is there any other way to know if it shall be hard to strip?
What do people mean about cards when they talk about monitors?
Is heat absorbing glass a good substitute for a fan to cool the lcd panel? And does the picture quality differ alot between a removed lcd panel between 10 and 14" and a 15" panel?

how does a stripped lcd panel connect to a stand alone dvd player?

Thank you to anyone who answers me : )
 
Firstly all OHP will be halogen. No OHP or commercial projectors are built with MH lamps. These lamps are only used by us DIY PJ builders as we have found that these lamps are economical in the long run, generate so much less heat than halogen and give out a more whiter light that halogen which is what they mean when they mention colour temperature. They are really lights used in the industrial trades. For example, a motor garage workshop will have those lamps, so will aquariums, greenhouses and some lamppost.

Talking about Halogen 250W and Halogen 400W OHP. Firstly they have transformers to power up the bulbs. A 250W transformer will not give out enough to power up a 400W bulbs and a 400W tranformer will overpower and blow the 250W lamp. Also the 400W bulb generates more heat. So the reason why they don't change from one bulb to the other is because they really have to change everything so you're just better off purchasing a 400W in the first place. The fixtures can be the same on both OHP's.

No when people modify OHP's, they remove halogen and install MH lamps. Reason being, halogen last 75 hours and MH last 20,000 Hours and the light is whiter. MH lamps need ballast (a transformer) and an ignitor which is used to power up the lamp on the initial start.

When we talk about singlet or triplet les, the triplet simply gives a more sharper but most importantly a dead square image as to a curved / bowed image.

15" screen will chop a bit off. When they talk about cards, they mean your graphics/video card/adaptor. If you don't have TV out or S-Video out on your monitor, then the only way to project a moving image will be via ur PC or laptop which has built in graphics card. If you want it to play from you DVD player, you will need to make sure it has TV out or S-video out at least.

You still need a fan regardless of special glasses. The quality of the image doesn't depend on the size of the screen but the resolution. The size just makes it bigger upon projection. Although the higher sized panels do tend to have higher resolutions in most cases. It all depends on how big you want the image. It's only noticable when its like over 200" mainly.
 
Thanks you've helped me loads gizmotech!

I'm just wondering now if

To insert a ballast that will run MH bulbs is it hard? is their a guide?

Is their an in depth guide to stripping a tft monitor? do most tfts monitors have the same basics? Some are harder or just cannot be used than others. Once you learn how to strip one monitor is it easy to strip another?

And also how can you tell if an OHP has a triple lens does the 'head' of the projector have a certain shape?

Also what does it means about the 'elements' used in the projector?
 
OK these metal halide projectors, when i look at websites even the companies you mention sbisdabomb they never say if the projector uses a metal halide bulb or not, how can i tell?

Also these FFC issues people talk about with monitors i'm gathering this is about whether they can be stripped or not. Could anyone go into greater detail what it is about?
 
The overheads that came with Metal Halide bulbs are not nearly as popular as the halogen variety. The biggest market for overheads would most likely be schools and a 2000 lumen halogen would be sufficient for their needs. The overheads that I was able to find all use expensive short arc mh bulbs anyway. It is much easier to buy any overhead that you can find with good optics and retrofit it with a mh bulb. Then you can pick the bulb to match your setup instead of the other way around.

The FFC is the set of wires that send the video info to the lcd panel from one or more control boards. They are very delicate and can be damaged very easily. If the screen manufacture has designed the panel so that the FFC ribbon is to short to move the control board out of the path of your light source then you have to be creative on how move the control board to make the panel usable. The key is to be very careful and take your time. No panel is unstripable from what I've heard, its just the panels with FFC issues take more time and creativity.

When they say "element" it's usually but not always is refering to one of the lenses. Either one of the projected lenses or one of the Frensel lenses.

Check out...

http://www6.tomshardware.com/howto/20041201/index.html

Hopefully it will answer some more of your questions. Its a step by step on how to build an DIY XGA projector using an overhead.

Zaner21
 
I see thanks zaner.

To retrofit the projector i will have to buy a ballast i should think and maybe an ignitor? i don't know much electronics, would the projector (optics aside) have to be built to use 400w bulbs in the first place? how does it all work to change a projector?
 
That's where the fun starts. :D You get to design your own setup. You first need to decide on what lcd panel to use. Be it 5", 7", 10", 15" or 17". Each size will require different sized optics. All of the optics are based on the size of your lcd panel except your reflector and condenser, if you use one. They would be based on your bulb. Also the smaller the lcd, the lower the wattage bulb you can use. 5"-10" lcd's would only need 250 watt bulbs to get a good picture. 15" - 17" needs more lumens so 400 watts seems to be the norm for that big of panel. If your going to retrofit an overhead then you would try to get the arc of the mh bulb in the exact same place at the filament of the original bulb. If you build your own enclosure then you get to play with focal lengths and experiment.

Zaner21
 
ok, does everybody change the optics in an ohp to fit the screen size? see the overhead projector on toms hardware, has he 'retrofitted' it to use a metal halide bulb and changed all the optics aswell? If i retrofit an ohp to use a metal halide bulb how do i know the arc length of the bulb originally in the projector and the bulb i will be changing it to use? And please please please do i need a ohp that was already designed to use 400w bulbs to covert to use 400w MH bulb? and what do i all have to do to change a projector to run a MH bulb?
 
The optics in most overheads should be big enough to fit a 15" panel. It might cut off a little bit all the way around the edges and maybe the corners. Shouldn't be too bad thought. It's been so long since I read that article from Tom's hardware. Did it say that he retrofitted his overhead? If you retrofit an overhead you don't have to match up the arc length of the mh bulb to the filament length of the halogen. It just needs to be the same distance away from the frensel lenses. No you don't have to find a 400 watt overhead to retrofit it to a 400 watt mh. Try a google search for H.I.D. or Metal Halide or High pressure sodium or... I think you need to learn the difference between arc lamps and filament bulbs. See if you can find out a good explanation of how they work. I don't have a good link to refer you too, sorry.

Zaner21
 
ok i have read a fair bit on H.I.D. lighting and filament bulbs, i now ask will the fan in the OHP be able to cope with the heat a metal halide bulb produces? and still i am confused on replacing the ballast and ignitor on the OHP will it be an easy job could you give me some more details on that? (oh man i never thought to get a cheap projector was going to have so much work!)
 
really cheap projector

First of all, you don't really have to retrofit an OHP with a Metal Halide lamp & ballast. You can just do what the Tom's fellow did: Strip the backlight off an LCD monitor panel and then lay it on a standard OHP (with all the original OHP parts). This will give you a projector that sits close to the screen, cuts off part of a 15" monitor, has a slightly yellow image, and needs a new lamp ($5-$10 US) every 250 hours.

Minor problems, if all you need is a way to project video like broadcast TV and DVDs: Most TVs cut off about 25% of the image at the sides anyway by overscanning. You get used to the yellow images within a few minutes, and the lamp cost is less than 4 cents US per hour!

If you don't have the skills to strip a monitor (and maybe extend the FFCs), then you can buy an OHP projection panel on eBay. That just lays directly on your OHP with no effort at all. The trade-offs are lower contrast and longer response time, but no work and no cut-off sides.

If you need to run Windows on your projector or you have another such high-resolution application, then that is a different set of requirements. THEN you need a better light source, wider fresnels, better optics, etc. But lots of people have laid a projector panel on an OHP and been happy with the results for years.

BTW: A 400 Watt MH lamp puts out LESS heat than a 400 Watt halogen lamp. That's one reason projector builders go to the expense of using MH.
 
Thank you Guy Grotke ok the fan will be fine if their is less heat from a metal halide. What i really really want right now is information on how to change an OHP that uses 250w halogen lamps to use 400w metal halide lamps. I don't have much electronic experience so could somebody please please help me with more of the details on that?

By the way i don't own an OHP yet, i'm hoping this will help me make a decision.
 
retrofitting with MH

Not at all difficult, if you can follow a simple schematic and understand how to strip wire ends and make connections with wire nuts.

First you buy a suitable MH lamp and matching ballast kit. You need a lamp that will fit inside the OHP box with the lamp arc at the same position as the original lamp filament. It should have a color temperature in the 5000 to 6000 K range, to match the color balance of an LCD backlight. The ballast may be magnetic (like a transformer) or electronic (sort of like a switching power supply). Magnetic are cheaper and heavier. Electronic cost more, but are much lighter and more efficient. Some lamps will specify "ONLY electronic ballast". A magnetic ballast kit has to be a type that matches the lamp manufacturer's specs. These usually have an ANSI code (like "M59", for example). With either type of ballast, you will get a wiring diagram and any other needed parts. A magnetic-type may include a capacitor (for phase load correction) and an ignitor (like a fluorescent lamp starter). An electronic-type does all of those things internally.

You connect the lamp socket wires to the ballast "lamp" wires or terminals. You connect the ballast's common or neutral wire to the neutral side of the line cord (usually white). Then you connect the hot side of the line cord (usually black) through a switch to the ballast's 120 VAC power wire or terminal. If there are multiple power tap wires, they will be labelled something like "120 240 270 480". Those let you connect to whatever main voltage you have. In the US, always use the "120" and cap the other wire ends individually with wire nuts. (They will be HOT when you turn on the power.) If the ballast kit included a capacitor and ignitor, connect them as indicated in the ballast wiring diagram.

A good shortcut to finding a lamp & ballast that work together is to just buy a set from one of the online stores: lumenlab.com, diyprojectorcompany.com, exclusiv-online.com all have kits.
 
Thanks Guy Grotke again. Is the old power supply, bulb holder, ect hard to remove from the projector? would there be a hole where the old power supply cable is and i run the new power supply cable through that? How would i attach the new ballast and power supply and bulb holder to the OHP case (with screws? if so, how?) and how does replacing the power supply affect the internal fan of the OHP?

Also if i buy an 8mm pc fan to cool the LCD is there an easy way to power it if i'm not connecting this projector to a pc?

And by the way do metal halides cost alot more to run in electricty than halogens?
 
Your killing me Smalls!!! Your killing me.

Hook them together with double sided tape. lol. Just kidding. Sorry It all depends on the ballast. If it has holes then you could use bolts or sheet metal screws. If it doesn't have holes then you would have to make some kind of metal straps. Stripping the old stuff out is easy. The hard part is stripping the LCD. Don't worry about retrofitting yet. Get your ohp and lcd and see if you like the picture quality with just that much. You can always adjust the setup down the road. Like Guy said, a lot of people are ok with halogen ohp's. The color differences can be overlooked because of the novelty of such a big screen. It's only when you are unsatisfied with those things that you start to tweak and change the set-up.

Electricity is billed in kilowatts. A kilowatt is 1000 watts. A 1000 watt mh would cost the same to run as a 1000 watt halogen but you could heat your house with the 1000 watt halogen but just warm your hands with a 1000 watt mh but the mh would light the whole neighborhood.

All of these silly questions depend on the items that you pick. Every manufacture makes things a little different. It's only when you purchase the items you are going to use that you will know for sure how easy is it take apart, how to hook the ballast to the ohp frame, how to do this, how to do that. Don't worry so much just get out there, get your hand dirty and start DIY'in.

Zaner21
 
Well, metal halide bulbs are anything but cold. If you tried warming your hands near a 1000W metal halide you'd probably end up cooking them. It's difficult for me to adjust things near my 400W bulb as-is. And it definitely makes a difference in the room temperature, something I'll welcome in the winter but not so much now with 90F averages. Oh well, shouldn't be inside watching movies during the summer anyway!
 
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