Home made projector!

[Dan_B]

i have disasembled 1 of them from the layout of the display it almost seems like they were desighned for this. the power supply is on a seperate board and just provides 12v 1.5a there is a vregulator on display board for 5v the display board is at the bottom of the case and the ribbon cable runs 8" to the top of the lcd so plenty of play in the cable. i may even be able to mount the driver board inside the ohp.

[Chernobyl]

Originally Posted by Dan_B

i have disasembled 1 of them from the layout of the display it almost seems like they were desighned for this. the power supply is on a seperate board and just provides 12v 1.5a there is a vregulator on display board for 5v the display board is at the bottom of the case and the ribbon cable runs 8" to the top of the lcd so plenty of play in the cable. i may even be able to mount the driver board inside the ohp.

Nice, it shouldnt be hard to get a PSU for it, I wish you luck.
By the looks of it you arent shy with electronics

Last night the bullet bit me and I decided to split the fresnel lense in 2 to try and get an even brighter picture.
The theory is this...

The Fresnel is made of 2 lenses, mated together so they appear to be just one lense.
The bottom of the 2 lenses gathers the light coming from the bulb/lense below and makes the light travel directly upwards.
The top lense takes the light travelling directly upwards and angles it towards the very top focussing lense.
Normally the 2 halves work together as one lense (sat below the LCD), the net result being that light is focussed to the top focal lense, passing through the LCD on the way.
By placing a fresnel lense above the LCD (between the LCD and the focal lense), more light that would escape sideways is captured and sent towards the top focal lense.

I left the bottom half of the fresnel inside the OHP in its normal location and placed the top half about 1cm higher than the LCD.
It really does work, the brightness across the screen is much more uniform, the corners are much brighter.
A cool side effect is the focus across the whole screen is much much better!!! So it seems the fresnel being below the LCD only somehow has difficulty allowing uniform focus.
but there are issues...

The fresnel halves ideally need to be aligned above/below each other exactly otherwise the image dims somewhat.
It is impossible to fit the top lense correctly above the LCD as it is way bigger, the LCD electronics get in the way. I will have to cut it to shape but wont be doing it just yet as I'm still investigating and thats a one way process!

When it was first powered up, the brightness wasnt uniform, being a fair bit dimmer around the edges. I adjusted the bulb height to compensate and saw a big improvement but couldnt move the bulb low enough so the edges were still too dark. I took the lower fresnel out from the inside of the OHP and placed it directly on the glass (the LCD sat on top of it) to see if the brightness does improve as hoped when further away from the bulb and indeed it is really good!
Unfortunately, the lower fresnel is now a little too close to the LCD as there is a mild herringbone pattern on the screen so I will remount the lower fresnel inside the OHP, probably attached directly to the underside of the glass.
The setup looks fairly ugly right now lol and there is work to do but its certainly an improvement.

Splitting the fresnel gives 3 benefits.
1) more light is trapped so overall brightness improves.
2) the light is more uniform over the whole screen, ie the corners almost match the centre of the screens brightness.
3) The focus is improved and the image is much sharper than before.
There is no longer a different focal zone in the centre of the screen.
The fresnels are slightly warped so the left/right of the screen arent focussed the same, I'll sort that later with a new fresnel.

Another effect that may be useful:
by adjusting the angle of the top fresnel, you can perform minor keystone correction! (ie if you are projecting a little upwards for example, the screen image will be trapezoidal in shape, you can correct for this!)
The only consideration being when the lense is at an angle, you cannot focus the whole screen. It is however a very sharp image now so a slight defocus doesnt hurt. I wont be doing that on mine as there is no need, food for thought though.

Here are a few photos of the work in progress.
splitting the fresnel is quite easy you just need to take care not to scratch the lenses. I took my time and did it slowly.

The last photo of the messy setup has the lower fresnel sat under the LCD with black card sat on top of it to stop light escaping into the room.
The upper fresnel is sat above the LCD with the cardboard shroud sort of balanced on top.

[Dan_B]

i was looking on ebay for an ohp and found this i didnt no you could buy these
http://cgi.ebay.co.uk/3M-800x600-nat...QQcmdZViewItem
not much use to me as res is to low.

[Chernobyl]

Originally Posted by Dan_B

i was looking on ebay for an ohp and found this i didnt no you could buy these
http://cgi.ebay.co.uk/3M-800x600-nat...QQcmdZViewItem
not much use to me as res is to low.

Theres quite a lot of panels around, the consensus seems to be that an LCD monitor does give superior results.

Try and get as high res as possible, I wish I had a 1280x1024 LCD as 1024x768 is starting to become low res and isnt 720p compatible.
I was previously conerned that the image wouldnt be sharp enough over the whole screen (due to non uniform focus) to allow higher res but after splitting the Fresnel lense, this is no longer a problem!
Now I'm researching making a 1600x1200 17" LCD projector which will need to be built into a box like many of the kits you can buy
I'm going to make it modular though so it can be easily modded.

I wont be making it until the hoo haa about HDCP/HDMI (copy protection) has settled for definite (yeah yeah I know Sony etc have said it wont be used til 2010 on displays but its hard to trust them so I'll wait a bit longer).

Dan_B, be sure to get an OHP that has triplet lenses as you will need to add the missing lenses later otherwise. I read that the triplet lense part is the top focal lense which is more complex.
Without a triplet lense you lose light and sharpness.
Happy hunting

ps
if you intend to mod it, try and get one that allows you to adjust the bulb height. Its known as a colour adjust or something like that.

[Streethawk]

wow!

I'm amazed this thread is still going guys!! I remember when it was in it's first decade

[Chernobyl]

lol, nice to see you here Streethawk

yeah I didnt imagine I would still be working on it after 1.5 years!
Its a great project and gets better and better.

I have another mod lined up, using a polished kitchen ladle as a rear reflector lol.
I can buy one pretty cheaply ready made for a projector from the US.
It surrounds the light core of the bulb reducing light losses substantially.
The cooling I have on the bulb will hopefully be sufficient for this mod as bulb heat wont be able to escape as easily.

[Daniel ~]

Chernobyl has pioneered this for AOA Readers and, I think, lit one or two fires under members along the way!

What a bright and shinning picture this makes! ":O}

[dsio]

Originally Posted by Daniel ~

Chernobyl has pioneered this for AOA Readers and, I think, lit one or two fires under members along the way!

What a bright and shinning picture this makes! ":O}

I believe this is a "Jolly Good Show!"

[Chernobyl]

Cheers guys
this is a nice place to share my experiences and is certainly one of the best behaved Forums I've come across, kudos.
Thanks for the support and a cool site.

and theres more...

The top fresnel doesnt fit on the LCD as the electronics are in the way so a slice has been chopped off, see photos.
The quality of the cut doesnt matter as that part of the fresnel isnt used. The only thing to be careful of is not to crack the Fresnel.
This method of cutting was very easy.

After playing with the split Fresnel lense for a bit I have found its a little tricky to set up optimally and am not sure if I have set it up at its absolute best yet.
The attached photo demonstrates what it looks like at the moment.
I'm holding a 12" ruler, the Simpsons window is 24" diagonal. This picture is massive
The background image is from the brilliant My Name is Earl.
I rotated the picture slightly to correct a wonky photo.

(My camera cant capture the brightness or colours quite right as it looks a lot better sat in front of it. On camera it still looks brighter in the centre and darker at the edges. In real life, you dont notice unless you look for it and even then its hard to see )

The location of the 2 Fresnel lense halves in relation to each other AND the location of the bulb is critical. If they arent all aligned correctly the picture can dim substantially.

To set it up:
1) The top lense is fitted over the LCD (1cm higher)
2) The bottom Fresnel is laid on the OHP with the LCD/lense assembly placed on top.
3) The LCD/lense assembly is moved around with the lower Fresnel stationary below while watching the projected image brightness. The picture gets darker then brighter in bands as its moved and gets brighter overall as the centres of the fresnel lenses line up until it seems it is brightest.
4) The whole dual lense/LCD assembly is moved around on the OHP glass until the centre of the lenses line up with the bulb. Again by watching the brightness the best location can be found.


There is another very good side effect of splitting the lenses...
As the fresnel lense is capable of fitting almost the whole 15" LCD screen and light now passes through the LCD vertically between the bottom and top lenses, the screen displayed has been made larger left/right and the corners are no longer cut off as light can hit the whole of the glass and therefore the whole of the fresnel used by the LCD!

The picture hardly needs any adjustment to fit on the screen now and its left/right size can be adjusted with only the LCDs settings. No need for Powerstrip to adjust it but... I have found that with default frequencies sent to the monitor I get an interference pattern that moves up the screen. Simply using powerstrip to change the size even a tiny amount stops this happening so I still use it. Your own experience may vary but its a very simple solution if you need it.

The picture is now 2.95 metres diagonal

[Daniel ~]

There it is! Bigger than LIFE! "
:O}

[spanielgita]

Hello all, esp chernobyl!

I am amazed and very pleased to see that the forum is still running strong!! well done chernobyl for all your efforts.

I don't know if you remember me from a while back, but i wrote some posts on this forum in the past. If you look at page 12 you can see my projector.

anyway - got a couple of things to say:

I was reading the lumenlabs forums the today and i noticed a topic all about removing the anti-glare sheet from the lcd panel in order to improve brightness, contrast and colour saturation. Looking through various people's succesful attempts i thought this might be something you guys would like to try. It seems to be a significant improvement.
I am aware that the lumen lab people are using a different setup to our ohp type movie projectors but i think the principle should remain the same. below is the link the the topic, you should def check it out

http://www.lumenlab.com/forums/index...topic=8283&hl=

My second thing is that i will be looking to extened my viewable screen area (by cutting the top of the projector and adding a bigger fresnel) and adding a new lighting system ( thinking of a 400w mh system) in the near future. so i will keep you updated on the project. its about time i improved my projector.

Dan

[Chernobyl]

Hey Dan, nice to see you again.
Glad your PJ is going strong.

Thanks for the info Dan, that is a fantastic mod!!!
I'm definitely doing it but may have to wait a week as I'm demo-ing the projector tomorrow and Sunday and it wouldnt be impressive if I tore the polarising filter. I would like to remove that too and get a first class after market polarising filter but that can wait until my next LCD when I go higher res.
I will have an issue with how close the bottom fresnel lense is after this mod (the LCD is practically sat on it!) so will need to move it a bit lower otherwise the picture will have very noticable herringbone patterns.

The link you gave shows many results of removing the Anti Glare filter from 15" LCDs and as such is perfect, many thanks!!
Also many thanks to Lumenlabs and all contributors, this is exactly the sort of mod I like
What is amazing is that soaking the top layer in water releases the glue


I may be able to help you increase the viewable area without as much trouble as cutting your OHP open.
Over the last week I split the fresnel lense into 2 parts with the bottom half placed below the LCD and the top half above the LCD.
Light travels from the bottom fresnel to the top one exactly upwards so as much light as can hit the fresnel will be forwarded through the LCD.
(edit: I also had to move the lower fresnel a bit further away from the bulb as it didnt look so good in the normal position. You may need to do the same.)

This differs from having the full fresnel below the LCD as the full fresnel immediately focusses its light towards the top lense, passing through the LCD at an angle which doesnt light up as much area of the LCD.

Brightness is now much more uniform over the whole screen and it is overall a bit brighter too. Focus has been improved drastically, all the focus zones are gone except for one caused by a slight warp in my fresnel.
Also I have no cut off corners any more.
Its a top class mod
With the mod you found and splitting the fresnel, a 250W bulb is enough for a 3 metre screen. Its about perfect right now, cant wait to remove the filter.

Do let us know what you try.

p.s.
Hi admins
I'm not receiving many emails that tell me a post has been made here including the last post by Spanielgita. This has been happening since last year.
I dont use any special anti spam software just MS Outlook and always check my junk mail folder so I dont know why this is happening.
Is it possible to check please?

[danrok]

I'm getting email notifications for this thread.

[spanielgita]

Glad you appreciate the info :> was looking at different advanced mods topics and that seemed the best one for the least effort. it even has an example using my exact monitor **15 inch samsung 510n** so i know it will work!!!

Now that i am on my summer break its a good time to get some improvements done!!! fed up of looking at 90% of the screen lol. my bulb went recently also so i am going to invest in a metal halide kit for sure.

I have started to extend my projector today, which is proving most tiresome lol! i only have a silly handheld hacksaw and the lid is made of metal! but its 3/4 done now and then all i have to do is file away the rough edges. I will be getting a bigger fresnel to accomodate the new lid area (a 31cm x 31cm fresnel). also been taking pics of the whole process but dont have my camera cable so i will post them later.

i did try splitting the fresnel i have at the moment (which i think is way to small), but it cracked even though i most carefull.... what technique did you use!? mines seemed to be fused together.it is also very ancient lol. i really dont want to break the new one because i think it will cost be about £20!

i would also love some help oredering the lighting system from that german website. you said the 250w was plenty bright enough but the price difference is minimal so do you think i would be better going for the 400w? how far away from the wall is your projector?

also (sorry for all the q's!!) do you think i will still be able to use the fresnel split technique even though i have widened my lid??

Regards

Dan

[spanielgita]

hey there again

i have a dilema! there are 2 fresnels that i need to choose between on ebay but i am unsure of which one to go for!

the first one has extra long focus?! its focal length is 432mm

http://cgi.ebay.co.uk/VR-X-LONG-FOCU...QQcmdZViewItem

the second one is a varifocal with a focal length of 330mm and 220mm

http://cgi.ebay.co.uk/LENS-PROJECTOR...QQcmdZViewItem

i think the second one would be better but i am unsure. seems like an ok price also.

Dan

[Chernobyl]

Yeah thats lucky you have an LCD that has been tested, mine hasnt featured there yet.
Worthy of note, some of them who have had the LCD in a projector for some time have found they need a much longer soak to free the Anti Glare film. This is a bit scary as its likely the glue holding the polarising filter will take on water as well. one user reported his polarising filter started to curl at the edges.

Most of the modders seem to be laying wet towels etc on the LCD.
I would wet a towel and lay the LCD down on it. That way you can make sure no water is getting into the edges and the towel wont dry out as there is no air contact. Also the weight of the LCD panel will promote a better contact with the wet towel

Aaah I see the need for the larger OHP casing. 310x310mm is a standard 15" fresnel size (the same as mine). The one you have must be a fair bit smaller!
From previous reading, it appears some Fresnels are sealed at the edges and need a hacksaw to open them. Yours could be one of these or maybe the glue has set rock hard. Hacksawing off the lugs which are used to hold it in place makes things awkward so its a good thing you are getting another lense.

This is the one I would buy as its definitely good for the job from the same guy I got the 250W bulb kit:
http://62.75.177.102/shop2/index.php...roid=7&skat=13
translate it here, German to English
http://world.altavista.com/
This one will come apart with a screwdriver they say. The glue isnt as strong so it will come apart easily.

The first fresnel you have selected is a bit small I think at 285x285mm.
The second one sounds like one 1/2 of a fresnel as he talks about using the grooved side which is only exposed when you split them apart (each half has a grooved side).
I may be wrong but best to be careful.

To see how I split mine, check back a few posts
Home made projector!
(I used a kitchen knife)

I see you already are running a 600W halogen bulb so you probably want the 400W MH Kit.
The 400W bulbs dont have UV stop so you definitely need a UV filter.
You may also need an InfraRed filter...
With a 250W UV stop bulb I get a mild temporary burnin if I leave a page on the screen too long in hot weather. How quickly it happens is directly related to how warm the room is and takes about 2 hours to appear on the hottest days. It goes away when the room cools, the picture is changed or it is turned off. It can take 1 to 5 hrs to go away.
I am going to improve the cooling to counter this as my setup is not optimised well.

That said, if you havent suffered any burnin with a 600W Halogen bulb you most likely dont need an IR filter if you keep the same protection in place.

The fresnel split technique is a must and will work regardless of your setup. You will have to play with the height of the bottom fresnel from the bulb and also adjust your cooling to blow cold air underneath the top fresnel to cool the LCD.
I would leave the refitting of the OHP top until you know it will be high enough to take the split fresnel. I found the lense needs to be a little further away (higher) from the bulb once split.
Even with the bulb height adjuster, I couldnt get the bulb far enough away so I put the bottom fresnel under the LCD for now I have a faint herringbone pattern (which will be worse when I remove the anti glare filter off the LCD) so am going to stick it underneath the OHP glass top.

You will need a new rear reflector for the new bulb.
I recently found this brilliant one and am ordering it when they tell me how to register with them securely. They dont use HTTPS which is worrying.
I emailed them about it last week but havent got a response yet.
http://www.diyprojectorcompany.com/c...products_id=43
Check to see if you have one of their methods of payment.

Good luck with the mods

ps
the German shop takes Paypal, as does the shop selling that rear reflector.

edit:
Forgot this bit - to get a 2.95 metre picture, the centre of the lenses/LCD is 2.5 metres away from the screen.
Forgot this bit too - when splitting the fresnel, you get a bigger picture for the same distance away from the screen.

[spanielgita]

the cutting of the projector lid has been completed, with some minor edge filing to do!!! took far too much work lol! i really want to get a fresnel and lighting kit now, but that german website is out of stock and i have no idea when they will be in stock again!!! aaaaaah so unfair... just want to get finished! anyone know of any other reliable fresnel lense stockists - no retail outlets in the uk sell them!

Dan

[Chernobyl]

Originally Posted by spanielgita

the cutting of the projector lid has been completed, with some minor edge filing to do!!! took far too much work lol! i really want to get a fresnel and lighting kit now, but that german website is out of stock and i have no idea when they will be in stock again!!! aaaaaah so unfair... just want to get finished! anyone know of any other reliable fresnel lense stockists - no retail outlets in the uk sell them!

Dan

wow you are right, theres nothing in the UK.
If you cant wait, order from the US.

This is one place
http://www.diyprojectorcompany.com/c...x.php?cPath=23
They dont have a secure server for registering. Purchases are made with Paypal so at least thats more secure.
They sell all the other bits too if you're desperate for those.

I cant quite believe the price difference in the light systems. 400W from US is $200, equivelant system from Germany is 80 Euros!
I waited months for the German site to get stock but it was worth it.
Good luck

I'll keep my eye open for new suppliers.

[Chernobyl]

my bad, the 400W light they sell is not the same type as the 250W they sell and that I use.

I cant recommend those bigger bulbs as the bulb casing is large enough to prevent optimal placement near the back reflector and the lense that sits just above the bulb (the condensor lense) has to be further away too.
It also means you cant use the special reflector (kitchen ladle ) that they sell.
All things considered you will not get as much of the light as you should and may need to have a larger space to fit the kit.

I've tried very hard to find somewhere else for you to buy a full kit from, suggestions from readers are welcome.
This is why I waited for the German site to get stock as there was little alternative (and they are goddam cheap!). Not much has changed in 1.5 years sadly.

[spanielgita]

thanks for your efforts chernobyl!!

i have an freind who may be able to get me a fresnel, as he works with optics. also i found a uk supplier for metal halide but i dont know if the system is ok.

http://www.bltdirect.com/product.php...tural+Daylight

also they sell "gear tray" which have the ballast, ignitor and capactor on it.

http://www.bltdirect.com/product.php...+Tray+400+Watt

what do you think of that? seem quite pricey also!

are they the same dimensions as yours? doesnt say if theres a uv stop also which is a concern.

When are you planning on removing your anti-glare??

there is also a 250w gear tray and halide bulb option, bought together they would be 100 pounds compared to the 400w option at 119..



dan