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Author Topic: LED projector bulbs ? on the way.
Pere Pasqual
Film Handler

Posts: 43
From: Gandia, València, Spain
Registered: May 2017


 - posted June 19, 2018 09:56 AM      Profile for Pere Pasqual   Author's Homepage   Email Pere Pasqual   Send New Private Message       Edit/Delete Post 
quote:

But you can't realistically mount a decent high powered LED flashlight in a GS-1200...

Again, I have to disagree. Have you taken a look at some of the flashlight links I've posted in my last message? The led chip + optics part is really small; less than the size of a 100w, 12v bulb (or a 150w, 24v).

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Adam Deierling
Jedi Master Film Handler

Posts: 708
From: OH
Registered: Nov 2010


 - posted June 19, 2018 10:02 AM      Profile for Adam Deierling   Email Adam Deierling   Send New Private Message       Edit/Delete Post 
If you disassemble them, sure...but your not going to get anywhere near the light output you will need. That "Lego Projector" is only projecting a few feet. Try projecting 20 feet... But I can see you wont believe me until you see it with you own eyes. So go head and give it a try. I hope you prove me wrong because I would love to have an LED conversion...

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Pere Pasqual
Film Handler

Posts: 43
From: Gandia, València, Spain
Registered: May 2017


 - posted June 20, 2018 01:51 AM      Profile for Pere Pasqual   Author's Homepage   Email Pere Pasqual   Send New Private Message       Edit/Delete Post 
quote:

If you disassemble them, sure...

Of course, my idea is to try whatever it works. I counted on that from the beginning. Among other reasons because there would be no way to fit a full-sized flashlight inside a projector without disassembling it. My idea is to permanently replace the original bulb without further notice or annoyance for the user, and to connect it to the tension/current source for the halogen bulb.

quote:

but your not going to get anywhere near the light output you will need. That "Lego Projector" is only projecting a few feet. Try projecting 20 feet...

Again, that project is from 7 years ago. LED lightning has evolved in an undescriptable way since them; you cannot compare. You have plenty of models claiming to output thousands of lumens for the price of a halogen bulb. Even if the real amount of light is fake and roughly half the stated, and considering that some percent of light is wasted due to unproper focusing, etc., now we have far more "light power" than 7 years ago.

quote:

But I can see you wont believe me until you see it with you own eyes. So go head and give it a try. I hope you prove me wrong because I would love to have an LED conversion...

I'm determined to at least try the flashlight mod. It looks like the cheapest and easiest attempt. And I don't want to bother or anything. It's that my curious mind finds the urge to at least make some attempt. Of course I confide in your vast experience, Adam, and I'm really taking it into account. It's just that I don't want to give up yet.

My 1st problem now is to decide between the vast amount of models and prizes. That needs some time. Any recommendations welcome!

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Adam Deierling
Jedi Master Film Handler

Posts: 708
From: OH
Registered: Nov 2010


 - posted June 20, 2018 08:24 AM      Profile for Adam Deierling   Email Adam Deierling   Send New Private Message       Edit/Delete Post 
I wish you nothing but the best. Like I said, I want you (or someone) to succeed in figuring it out. I am simply done wasting money trying to figure out myself...

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Brian Fretwell
Phenomenal Film Handler

Posts: 1694
From: London, UK
Registered: Jun 2014


 - posted June 20, 2018 05:08 PM      Profile for Brian Fretwell   Email Brian Fretwell   Send New Private Message       Edit/Delete Post 
I suspect really old projectors with condenser lenses rather than "spaceman" lamps or dichroric reflectors would take LED replacements easier.

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Lee McCaffrey
Junior
Posts: 13
From: Newton Abbot, Devon, England
Registered: Jun 2018


 - posted June 21, 2018 04:03 PM      Profile for Lee McCaffrey   Email Lee McCaffrey   Send New Private Message       Edit/Delete Post 
LG and Optoma/Coretronics have made a number of LED projectors, most of them use 3 high power LEDs and dichroic filters in order to generate the sequential RGB light required for the DMD chip to create the projected image. In the same way a colour wheel modulates the light output from the UHP lamp in conventional DLP projectors, the LEDs in an LED projector pulse rapidly in succession. The pulsing on/off nature allows the LEDs to be overdriven slightly to garner more light output.
I would imagine the LEDs used in these sorts of projectors would be the best match for a modified film projector, filtering as required to obtain the optimum colour spectrum. They could in theory also be programmed to operate as an optical 'shutter' in place of the mechanical shutter.
Digital DLP projectors typically use integrator rods (or lightpipes) to concentrate the light output onto the DMD which in some cases are similar in size to a super 8mm frame. As has been discussed before the problem with LEDs is focussing the light output onto such a small point. Philips has developed HLD (High Lumen Density) ColorSpark LEDs to overcome this 'entendue' effect. These are said to perform much better in digital projectors although as with anything new they are most likely much more expensive.

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Pere Pasqual
Film Handler

Posts: 43
From: Gandia, València, Spain
Registered: May 2017


 - posted June 28, 2018 10:56 AM      Profile for Pere Pasqual   Author's Homepage   Email Pere Pasqual   Send New Private Message       Edit/Delete Post 
I think this is getting out of control.

Yeah Lee, maybe thos LEDs are wonderful, but I think we don't need to go that far. I've found another video of another person who modded an old projector into using a flashlight:

https://www.youtube.com/watch?v=cNE1qBmWfWY

The description says that he's getting more light compared to the original bulb. And, again, that video is from 2014. We are in 2018 and technology has evolved considerable since then regarding LEDs and flashlights. What's seen in this video looks fairly easy to accomplish, and by using a 2000+ "claimed" lumens flashlight I think we should expect at least half that, nearly equal to the halogen rating.

Anyway, I already got one of those flat cheap 10 W LED and plan to attempt some experiments during this weekend. Moreover, I've asked for help in a Spanish LED flashlight forum (there are a number of these on the internet) and I've got already some valueable info. Take a look at these ones:

https://www.fasttech.com/products/0/10031707/7281007-cree-xhp50-2-j4-5a-2654lm -4000k-led-emitter

https://www.fasttech.com/products/0/10032925/7492701-22mm-3000ma-1-mode-dim mable-led-driver-circuit

The 1st one is an XHP50.2, and yeah, these are not "fake" lumens, but "real" ANSI measured ones; the 2nd one is an inexpensive driver which should work with out projectors' bulb 12 V input. The only missing piece is a fan and, maybe, a lens. After some quick googling I found that they at least seem to exist and are suitable for this model of LED, with really narrow beam angles. I have yet to find where to buy them, but let's got step by step: 1st with the flat 10 W LED, then with the XHP50.2 without a lens, and see what happens.

Last but not least: looks like out-of-the-box ready replacements are starting to make their appearance. I cannot remember if we've already talked of these ones:

https://es.aliexpress.com/store/product/Hi gh-lumen-CREE-MR16-LED-spot-light-AC-DC-12V-6W-9W-12W-15W-COB-High/210139_32301397267.html

The one from the left seems almost the needed amount (they say it's a proper replacement for 70 W halogens, and claimed to produce nearly 900 lm), but some kind of of mod should be done in order to mount them inside a projector as there are longer. But you can see they are from the proper connection and tension (12 V DC), and look like our old friend dichroic ones with their and properly "condensed" light beam. They deserve a try at least.

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Lee McCaffrey
Junior
Posts: 13
From: Newton Abbot, Devon, England
Registered: Jun 2018


 - posted June 28, 2018 05:32 PM      Profile for Lee McCaffrey   Email Lee McCaffrey   Send New Private Message       Edit/Delete Post 
Pere, I wasn't trying to derail the thread or suggest using those particular LEDs, just highlighting what is currently being used in commercial LED projector offerings, and wondering if the principles could be applied to our film projectors.
I agree with you that the most important thing for now is getting something that works, and works well, especially for the projectors out there for which new lamps are becoming scarce/obsolete. The cheaper running costs and longer life would be an extra bonus! Good luck with the trials.

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Pere Pasqual
Film Handler

Posts: 43
From: Gandia, València, Spain
Registered: May 2017


 - posted June 29, 2018 06:18 AM      Profile for Pere Pasqual   Author's Homepage   Email Pere Pasqual   Send New Private Message       Edit/Delete Post 
Don't worry, Lee. Of course I understand the purpose of your message, and it's very important to be aware of the current state-of-the-art available techonology.

That said, my goal is to try to get results with the already, afordable, available technology, which I suspect is more than enough to achieve, at least, the same performance that with the old halogen bulbs.

I've gone one step forward from my previous message and, instead of trying with XHP50.2, I've already ordered one of these:

https://www.fasttech.com/p/8894801

That's a Cree XHP70.2 6500K LED, capable of outputting up to ¡4292! lumen, with an emitting surface of 7x7 mm, which is slightly more than the size of a 5.79 x 4.01 mm super 8 frame dimensions. Even with a loss of, let's say, 50% light (to exaggerate things to a extreme worst case), that should clearly outperform the lumen amount of an halogen. I've already found 5º narrow focusing lenses on eBay suitable for these type of lead (my goal was to try to use 3º ones, but haven't found any of these yet). I'm not sure if they will be really needed, but due to their cheapness I want to try them anyway to see if it makes a difference.

Now it's just a matter of time to get them and try.

Adam, have you tried any of these leds already?

PS: this is the companion driver I've also ordered

https://www.fasttech.com/p/7217304

which, with it's maximum of 4500 mA, should deliver a bit less than the theoretical maximum rating, but plenty of them anyway.

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Brian Fretwell
Phenomenal Film Handler

Posts: 1694
From: London, UK
Registered: Jun 2014


 - posted June 29, 2018 07:37 AM      Profile for Brian Fretwell   Email Brian Fretwell   Send New Private Message       Edit/Delete Post 
That lamp looks like it has a lens on it already, it would be interesting to see how the beam spreads from that (ie if it concentrates first then spreads).

Good luck with your project and don't forget the heat sink for the chip.

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Alan Gouger
Master Film Handler

Posts: 451
From: Florida
Registered: Jun 2003


 - posted June 29, 2018 07:38 AM      Profile for Alan Gouger   Email Alan Gouger   Send New Private Message       Edit/Delete Post 
I have tried several Cree drivers/LED clusters much brighter than what is mentioned here including several flashlights. Unfortunately most of the light does not make it through the film gate. You will need some sort of reflector to capture and redirect the light. I have tried several but have yet to find the right combo.

In theory LED makes sense but of all the alternative light source options avail this is probably the hardest to implement properly. We know it can be done because there are several video projector manufactures offering RGB LED projectors with enough light output to drive a large screen but they have a complicated light path with several custom optics between the LED and lens. Due to the compact nature of S8 projection we have very limited space between the lamp and lens to work with.

It may be more efficient to build a external light box where you can work with the brightest LED cluster and feed the projector with a two foot fiber optic cable, no heat at the projector. There is light loss due to using the fiber optic but it is easily over come if using a brighter LED. The fiber optic is point source and more efficient at delivering the light to the film gate. You now have room to add an optic if need be. Cinema laser projectors are using this method.

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Pere Pasqual
Film Handler

Posts: 43
From: Gandia, València, Spain
Registered: May 2017


 - posted July 02, 2018 02:47 AM      Profile for Pere Pasqual   Author's Homepage   Email Pere Pasqual   Send New Private Message       Edit/Delete Post 
quote:

That lamp looks like it has a lens on it already

I think it's not a lens at all; they call that a "dome"; apparently it's featured in most led chips, and it seems to have some effect in the "halo" or difussion of the projected light; in fact, I've seen they sometimes apply some "mod" to them called "dedoming" - looks like they get some extra amount of light by doing this. But who knows - I haven't investigated it deeply (and probably won't do).

quote:

I have tried several Cree drivers/LED clusters much brighter than what is mentioned here including several flashlights. Unfortunately most of the light does not make it through the film gate. You will need some sort of reflector to capture and redirect the light. I have tried several but have yet to find the right combo.

Maybe the difference is that what I'm attempting here is not a cluster, but a single chip, nearly the size of a 8mm gate, which claims to deliver the stated amount of light. That makes a difference from the usual cluster/array of leds.

And also, as I've said previously, I've ordered a 5º lens also. Looks narrow enough to me. I'm not sure if I can use both a lens and a reflector at the same time with this arrangement. I'll see when I have it in my hands.

quote:

It may be more efficient to build a external light box where you can work with the brightest LED cluster and feed the projector with a two foot fiber optic cable

No idea on how this works. I think this is completely out of my scope...

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