Hi all.

Well i decided it was about time i started a blog. This will be my second projector, the first was a standard coffin that I wrecked while moving house.

Ive been collecting parts for many many months now, and after 8 months of inactivity I have decided to get cracking over the Xmas break

So what is in it?


Reflector
Pro Reflector
Also, an Aluminium mirror surfaced extension reflector to aid condensor

Bulb
Pulse Strike 400W

Condensor
4 x 6.5 as used by Simul8r


AS OF 19/01/2007 SPEC OF LIGHT BOX CHANGED

Im using a dukane 680 now. Kicks out 7800 lumens as standard.

So should be getting around 700 Lumens once the LCD is in place

Rear Fresnels
220 mm rear 3DLens.com 0.2mm pitch
or
330 mm rear 3DLens.com 0.2mm pitch

Front Fresnels
550 mm front 3DLens.com 0.2mm pitch
(probably lens shifting... )

LCD
Sharp WUXGA Panel
Will strip antiglare, so may need 3D lens replacement polarisors

Front surfac mirror
From lumen lab

Triplet
Beseler 18" EF triplet (xxbloodxx4 has sent me her triplet. I have still to play with it)
or
135mm DIYcompany triplet, that i already have. (probably going to sell it!!)


Screen
80" x 60" Dalite High Power screen imported from America (was half the price of buyinig in UK!!)
I will make an adjustable black aspect changing border.. This arrived the other day, its way cool


I also have eBallast and Lumen lab ultraviolet sheeting too.




The enclosure will be built in stages, I will be making
1/ A light box
2/ A sled containing fresnels and LCD panel
3/ A triplet holdinng system (will start with DIYPC 135mm Lens mount, while i wait for xxbloodxx4 18" Beseler.
4/ A tray for the LCD controller
5/ A tray for the eBallast and other electronics

These items are all modular, what enclosure i place them into is unknown at this time.

However it is likely to be a retractable floor standing corner table unit, about 50cm tall... this will be expandable to 1 metre tall, difference in height is gained by collapsing the triplet down onto the front fresnel, triplet and mirror would therefor be in a box that expands out of the centre of the table. When not in use, the front section of the projector, which is mostly air, is non existant.


Well its 12:35 now, so i am off to bed. Tommorrow will be either, light box or LCD sled day one! I might even make a router mount to cut variable size circles... i need the practice!

OK its mid day over here.

I have built my work stand, and proved i can accurately cut 45 degree slices through aluminium using my mitre saw.

So now I need to prove i can cut straight long edges through soft aluminium....

Have an idea for doing this with a jig saw, lots of L section aluminium and some clamps...

Right on to building the light box.

Im copying the sort of design that simul8r used, however i have some box section aluminium im using to make a box frame. On to this i will rivet/bolt aluminium sheet to make the box sides.

The bulb is going to be attached inside the box onto 3 sets of sliding racks, each with a screw thread to accurately position it. This way i get accurate alignment in all 3 Axis.

The reflector and condensor lens will be attached via 12cm fan grills cut to size. These will then be attached to sliding racks with screw threads for accurate alignment inn the light box.

All of this is onna take an age to make, but i think it should allow me to tweak the position of everything innosde the lightbox with worry about messing up alignment of individual pieces.

Once inside the projector, I will be able to move the fresnel/LCD sled relative to the lightbox.

Will post pics a little later!

Trust me, thats better than NOT soaking it and cracking the panel as you pull off the reflective film! I ruined my panel, but hopefully you will not. Good luck on your build.

Hey Lucky_me

I read about your LCD, thats a real shame dude!! But its good to see you are working on your build again



OK i have taken lots of pictures today, the light box frame is almost done. Tommorrow i will cut the side panels, and make the bulb mount, air ducts, reflector and condensor mounts.

Right time for some pics.. bear with me while i figure out how to do this

OK, for a laugh here is a 400W t15 shining through my window, next to a street lamp!!



This really really freaked the neighbours out when i build my prototype projector last year!

On to somme pics for anyone who wants to make a light box out of aluminium...

Cut lots of sections of aluminium to make the frame


I used a Mitre saw for this, luckly the aluminium is soft enough for my blade!


Make a jig ready to drill and bolt the frame ends together...


A finished bolted, aligned section

Bolting together the box base frame


A Box end with fan wedged in place, the box base, and the other box side, where the bulb will be attached


And finally (for now!) an idea of what this is all about! (Please ignore the lemsip, i have a cold )


Thats it for now....

I need to work out how to attach larger images...

EDIT



Looks like i figured it out!!!

Been busy constructing other parts of the projector today.

Made the light box bottom and sides.


Made mounts for the condensor lens and Pro reflector. Cut the top plate for the light box, with a circular cut out for the condensor. (Broke my jig saw in the process, the thread for clamping the bottom plate is inside the saw, and is plastic I stripped thread when tightening down the circular cutting plate i made )

Started making slide rails for the front-back, left-right, in-out movement of the bulb and the reflector. This is very complicated, its taken 3 attempts to find a way of doing this without a pillar drill to accurately make alligned holes.. oh i wish i had a workshop

Pics to follow.. but i now have to go pack for xmas holidays in Spain...

Well its been a dredge of a week. Ive been ill so not much progress going on!

But i have made the adjustable mounting for the bulb (well i made them 3 times attempt 3 worked!). This is a set of aluminium fittings that slide across each other in 3 Dimensions, so i get seperate up/down, left/right and in/out movement for the bulb, adjusted using a screw threaded rack for each dimension.

This comes in very handly for finely adjusting the location of the bulb in the light box.

I should be able to fit the condensor lens fairly soon. Then after that i need an adjustable mount for the reflector. However this time round making it should be much easier, I'll copy the design from the bulb mount.



Im a programmer by trade, and in that job, when you make a mistake you just press the delete key, then correct your error..... Making these projectors really makes you sit down and think long and hard before you pick up your tools and "go at it!"

Its a great learning experience in the art of patience.... if you dont have it, it costs you time and money

Oh on another note, I forgot to mention that my 18" Beseler lens has turned up at work... Not back there till monday though, so pictures will follow... (I always so that i know, but it will happen, i have to take some of the light box for you all)


The Beseler lens supposedly still has its focusing mechanism attached, this will save me a lot of hassle if its self contained, and can be transplanted into the projector in a "nice" manner....

I use the Buhl focus slide and it worked OK.

I only made three light boxes! One too tall one too skiny and one just almost right.

It sure is time consuming working with aluminium, but i think its going to be worth it in the end.

The interesting thing will come when i get round to constructing the telescopic top section of the projector. If you take very rough measurements, then you have two sections to the Projector box:-

1 The one with the Bulb, fresnels and LCDs is roughly 400 mm tall,
2 The other section, spacing the Projection lens from the LCD is roughly 600mm tall

Its a big old box that is not used most of the time. Im going to try and make a two section telescopic top to the projector, so that when not in use, the projector "box" is around 450 mm tall. Then, when you want to use it, you pull the two section top into place, and this extends out to the full 1000mm (approx) height.

Ive not seen this done around here yet. I guess the weight of the projection lens, attached to a frame of the required type is going to be pretty hard to engineer

Ok Hold it...!!!

Progress has come to a shreeking halt.

I have been looking round for a way to improve my light engine lately, as some of you know.

And I have found a light engine that uses the OSRAM HMI 575W bulb, and kicks out 14,000 Lumens without an LCD panel. Yes you read that right.

Im being a little secretive because I havent secured it yet. But, its an OHP...

Soon enough I will divolge more info, because I'll either buy it, or some kit from another location using the same bulb.

Either way this bulb has a very short arc, and kicks out 49,000 lumens. The life is only 750 - 1000 hours, buy ebay sells replacement bulbs for around the £30 mark. I want 1080P for less than £3000 and i dont want to spend £300 on bulbs every few months, so this system although more expensive than a standard setup is still within my ball park allowance for the project.

So I now have two old style lumenlab e-ballasts and two T15 pulse strike bulbs im not using. Im sure I'll put them up for sale once i have recieved these new parts.....

Thats awesome i look forward to the update. I like the HMI bulbs because they tend to be smaller, and some are hot restrike. But the life still bothers me a bit. I look forward to the info.

building the projector isn't too mucn unlike programming..the more you sit down and work out your logic first the less headaches you'll have during the build. the difference is all the "unknowns" that you just didn't think about that pop up while you're building.

I've noticed many people are building "lightgates" now instead of the standard bulb/reflector setup. What is the benefit of doing this? Is it to contain the heat given off by the bulb? wouldn't it make it hotter in the box having a light gate since the bulb is trapped in a small area and the aluminum wrapped around it is also absorbing all this heat? (I know there is a fan exhausting it but can it keep up?

just curious as to the benefits of the lightbox.

Light gates do make the box the bulb is in hotter, but only if you dont have a big fan blowing air through it.

The main reason for me was to be able to mount a reflector, bulb and condensor in one box, where it is sealed to the rest of the projector. That way the LCD, fresnels and electronics are not picking up as much heat from the Bulb as they would do without the lightbox. Only the heat from the infrared light shinning through the condensor still gets to the LCD and fresnels, but the radiated heat from the 6-900 degree bulb filament is expelled straight away...

Also, beacuse the light bulb, condensor and reflector are in there own box, I can focus the air blowing over these components with two 12cm fans, blowing air through the lightbox like a force nine gail!! That would not be possible with an open box.

almost thou persuadest me to build a lightbox. I know SJ made his out of an old computer case. It shouldn't be hard to bend it to shape...hmmmmmmm. I don't know the implications of wiring 3 fans to a 12v, 1.25amp wall wart though..I suppose I shall find out!

With the light box do you still put flashing around the sides of the box in the general vicinity of the bulb?

so who's going to use liquid cooling on their lightbox

If you make the lightox out of wood then putting flashing inside it is a good idea. But generally just make sure there is no electronics inside, or near the light box... condensor, bulb, reflector and bulb holder... plus fans!!

Still waiting on OHP.......

But in 3 days time i will know if i have it.

On the details, the OHP consumes 900W, but the bulb is 575W, so the bulb is overdriven to pump ou this 12,000 - 14,000 lumens..... This bulb has a normal life of 750 hours, so i recon overdriving will shorten this life.

Luckly the OHP has a 50% power saving mode, that should decrease lumen output to say 6-7000 lumens.. and lengthen bulb life

I will take the lightbox, ballast and controls from the OHP, also i might take the front surface mirror as well...

I think this thing will be a very bright beast once its done.. just 3 days of wait to see what its going to cost me!

No way........

The bidding went all the way up to 256 pounds!! And the other guy still beat me to the post!

Oh well, I will now have to go for the second option, a 5600 lumen Dukane OHP from ebay in America. There are plenty of them arround )

Just found a Dukane 680 on ebay. It has a cracked fresnel lens, so the shop was selling it for $80

Naturally after yesterdays mishap I bought this one, roughly 10 times cheaper than the previous one i was trying to get!

Now the dukane kicks out 7800 lumens, so after tweaks i will expect around 700 lumens on screen. And if this is not the case, or if i find a higher lumen output OHP, then i will replace the fresnel with one of many spares i have and flog it again on ebay for a profit... nice

The HMI 575W lamp looks like it would work great. Is there any other way to get a ballast, besides the ohp?

Now that you found a OHP I found the 3M one I was trying to rember. The 9850

http://www.mbelectronics.com/quickreferenceguide/9850ipb.pdf

It makes 7000 to 11000 peak ANSI.

If you look at the pdf you will see they use a different lamp and reflector. The reflector might be a paroblic and the lamp is a SE one.

I might try to find a replacment reflector for my lamp. If I do it should work for your lamp too.

Yep i found one that sold on ebay about 2 months ago... I like this OHP too, if you do find a reflector for it, then i might be up for one also....

If i could find this OHP on ebay it would be great.

Yep.

If you go over to the Extreme Mods forum you will see loads of info in the overclocking lamps and ballast thread

Also search fro "575W" on all forums

Finally i have a tracking number for my OHP!!

Horray, that should mean im back here next week with some pictures.........

At last!

The dukane 680 has arrived, and it says it runs at 7800 lumens! Now thats good news as i should get around the 8-10% of that at the screen.

It arrived beaten up, the internal mirror is smashed to oblivion, as well as the glass shield, but not to worry, I only want the lightbox section.

I'll clean the glass out, and start it tonight!

Im worried your reflector may be cracked if it took a beating.
Mine was in seemingly good-shape aside from the reflector.
A few other peeps who used this engine got them with a cracked reflector too.
Good news is, it should stay together if your gental with it.
Good luck!
Thats one bright light. Hot too

i'd have to look but i think i saved the reflector from my 680 ohp if yours is cracked or damaged and i still have it laying around i can send it to you for just the price of shipping.

Well since its Robs&Johns plog, they get 1st dibs, but...
If Rob's isnt cracked, im definetly interested, and will gladly add some to the cost of shipping!

Rob,

Glad to see the 680 has finally arrived. A word of caution, if you remove the lamp, re-install it with the nipple either up or down, not facing the reflector or precondensor. Also, remember these light engines were not originally designed to illuminate an LCD as large as 15 inches. I had a bright spot in the centre of my projection until I removed the Dukane precondensor and moved the light box closer to the collimating fresnel (my PJ's arc to fresnel distance is 204mm rather than 220mm). Keep components as adjustable as possible.

I just replaced my 400w ushio setup with a 575w light engine out of a Dukane 680. I have no hot spots at all, but i also use a 330mm fresnel instead of the 220mm. I think the key to getting that light engine to work with a 15"+/- lcd is to use a longer fl rear fresnel.

I have never been happier with my projector now that i have the 575w light engine. I can watch movies with 8 75w lights on in the room and i'm completely happy with the results.

Im now going with a 15.4" 1280x800 monitor for the native wide screen. I just hope the extra .4" diagonal wont put the light cone inside of the viewing area. The light cone in my current projector just barely covers the rear fresnel as it is, but i think the extra .4" will fit.

So, i think in the end your better off going with the 330mm fresnel for a 15"+/- projector with the 575w light engine if you want to keep the condenser.

Good luck.

Good point jc1965. The original Dukane collimating fresnel is somewhat over 300mm, if I remember correctly. I didn't separate the fresnels so they could be measured. I used the Lumenlab 220mm fresnel because it was readily available and would allow a shorter box.

Yep, its a dual 330 for even brightness. I guess it dosent work as good with a 15 " panel, but the precondensor lets you put the rear 330 fres at like 190mm with a smaller panel

Wow lots of replys, and seems everyone is excited for me

Well the reflector is the only thing that is not broken so who ever wants can have it!!

The light strikes, and the reflector, precondensor ands fans all work, took hours to clean all the glass off my living room floor though

Im so happy it works... its always a gamble buying broken bits from ebay!!

Dont forget that yor original 15" panel is 4:3 ratio... if you do the math, then taking a 15.4" 16:9 ratio screen is actually the equivelent of a 16.5" 4:3 screen

But i'll be happy if yours works... since im going with a 15.4" one too.

The solution i have at the moment, is a highly polished mirror finish aluminium sheet, that is slightly curved to spreadout the light onto the 15.4" LCD... using a 330mm rear fresnel...

Its actually fairly easy, and its no problem buying the aluminium. Dont forget that the front surface mirrors are the same thing, highly polished aluminium mounted on a sheet of glass. In the UK you can get mirror finish aluminium sheets at 1000mm * 600mm for about £30.

You calculate the curviture, then get your mate with the CNC machine to machine you some mdf pieces with the correct curve profile, then mount your bent front surface mirror on them, and voila! a mirror with a slight curve accross its surface.

Alternatly, the required curve is a subsection of a cylinder surface, so you can mount your router/jigsaw on a very very long arm and cut a shallow curve section of MDF. a few of these curve sections should be enough to glue/fasten the aluminium to.

You only want to wrap the aluminium round a section of a cylinder shape... not a sphere... since its only the width of the 16:9 LCD that requires the extra width in the light spread... the height of the LCD is actually slightly less than the 15" 4:3 LCD panel, so, the light path fits vertically... only problem is on the horizontal.

http://www.fresneltech.com/pdf/FresnelLenses.pdf

page 11 of the PDF

item 41 406mm Fresnel focal length 370 by 370 mm size
item 48.2 457mm fresnel focal length 405 by 405 mm size


Now, im not sure what size would be required, but one of these would be great if you want to use the precondensor with a 15.4" LCD!!!

Any thoughts anyone?

EDIT: Blimey!!!!!!! I just saw the price!!!!!! Incredible!! 190 dollars!

Wow,
I think Dazzla has stated we really want closer to 400mm for the front fres and triplet FL regardless of panel size.
Too bad on that price
Ouchy.

You guys are over working this. You don't need to change the rear fresnel but at most the condenser lens.

First a slight adjustment of the lamp to condenser distance and light box might fill the rear fresnel. If not a longer fl condense lens will be needed. like this one.

http://diy-beamer.com/EN/store/comersus_vi...p?idProduct=268

Now i never could find that website... Foxed by the "-" in the midle of the address!

Cheers ArizonaVideo.

Durinng searching for "Dukane" on these forums i found a photograph of a comparison between the back and front fresnels of the dukane projectors. The photo showed a coke can magnified through the back and front lenses. And two pictures, with identical setup distances looked different. Only explaination? ront and rear fresnel are no the same focal length. I believe they are 220mm / 330mm.

Im gonna split the fresnels and try the same test :-) If it does turn out that the rear fresnel is 220mm FL then i can replace it with a 33o and no other changes will be needed

FWIW, the fresnels on my Dukane 670 were 220 and 330.

i cant get my lenses apart :-) Any ideas? :-)

I just wrapped mine in cellophane and cut them on my miter saw. Once you get beyond the glue line at the edges they are no longer attached. The acrylic melted a bit at the edges and had to be scraped off. It's also little messy--better have some compressed air on hand to blow the acrylic dust out of the fresnel grooves.

Point being, however you cut it, if you just cut beyond the glue lines they should come apart naturally.

EDIT: Are the Dukane fresnels even big enough for your 15.4" panel?

Ok a big knife always helps.

I have uploaded some photos of the Dukane and of a test i did on the fresnel lenses.

I can confirm that... my Dukane 680 at least.... has fresnels of different focal lengths.

I did a test where i took photos of two identical bottles side by side, projected through the fresnel lenses placed and aligned side by side.

I made sure everything was aligned and measured so that the camera would see identical pictures of the bottles through the fresnel lenses, as long as the fresnel lenses both had identical focal lengths.

Test setup....

• Joined lenses together side by side
• Aligned camera to look at lenses with split between them exactly centre of frame. and made sure camera lens was parrallell to fresnels.
• Placed two identical bottles behind fresnel lenses equidistant and at identical positions relative to the centre of each fresnel lens.
• Took photos at different distances from fresnels.

Results........

What i found was that one fresnel lens saw a much more magnified picture of the bottle than the other fresnel lens... A.K.A the focal lengths are not the same.

I measured the focal lengths at:-

• Between 200 and 240 millimetres for the rear fresnel.
• Between 320 and 360 mm for the front fresnel.

I have no photos of measuring this, since I would need four hands for fresnel, steel ruler, camera focus and shutter!!



Setup:-






Two photos of the projected bottles, showing that the fresnels have different focal lengths:-








So there you go! Different focal lengths!

Oh look.......

A gutted Dukane 680.....



A close up of the lightbox... The reason i wanted this thing....



After 5 seconds...



After 20 seconds... (had to turn all the lights on to get anything other than a black photo with a bright white smudge in the middle!

Oh i have no intention of using them.. I just want to see if these are 330/330 fresnels or 220/330 fresnels.

If they are the later.. which it turns out they are, then i can swap the 220 rear fresnel for a wider 330 fresnel so that I can use the precondensor with a 15.4" panel.

As you know, the issue with using a 220mm rear fresnel with the existing precondensor lens, is that the rear fresnel would need to be wider, and therefore would stretch outside the usable beam of light that precondensor is projecting.

With a 330 mm rear fresnel, the precondensor can be moved back, and the projected light cone will fill the entire LCD... Hopefully that will be one problem solved

More time will tell....

Sounds like you've some good ideas, Rob. The setup in those Dukane OHPs is a little strange (at least to me). But then, I'm not an optics expert. I never separated the fresnels from my 680, but measured the distance from the lamp arc to the internal mirror and from the mirror to fresnel. It is over 300mm. So, Dukane used a 220mm fresnel spaced about 300mm or so from the lamp arc? Maybe the extra 100mm is due to the the use of the specific precondenser. With a bit of experimenting, the 575w hmi should work well with the 15.4 inch panel.

Umm that is a little strange! I have been startinng to wonder if there were a few revisions to the Dukane OHP's. Since that is now two people who have stated the rear fresnel is 300+/- mm focal length, and few people who have stated they are around the 220+/- mm focal length.

I made the same measurement as you and got a distance of under 240 mm from bulb centre to the center of the fresnel.. It is very curious!!

Perhaps there were revisions to the the Dukanes. On mine (model 28A680, as noted on the bottom of the ohp), the distance from the lamp arc to the surface of the internal mirror alone was ~210mm, then upwards to the fresnels. It really doesn't matter, but Sunday afternoon, I finally separated my two Dukane fresnels and measured their FLs. To be sure the measurements were close, I first measured my two Lumenlab fresnels, since I am sure of their FLs. One of the Dukanes measured ~350mm, the other ~380mm. No wonder the unmodified light box from that ohp didn't work well with my 220mm LL fresnel!

It does matter to me Its confirmation that not all of these OHP's are the same! Your experience was one of the reasons i went this route, so to hear that your fresnels are different focal lengths to mine, means that a) I have been very fortunate! and I shouldnt need to many modifications.

Yeah i noticed that when using the 220mm pro rear Fresnel from LL i had to remove that precondenser from the light box because it would not shed enough light to fill the 220 Fresnel when placed roughly 220mm from the lamp arc. since i already built the box to those specs i didn't' have the room to move the rear Fresnel to 300mm or longer to see if that helped at all.