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Old August 31st, 2004, 03:42 AM   #61
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Hey Mike I've tried alot of LED's and even have the same LED panel array you have. Are you sure you want to run off only 12V because the output is much higher at 14V with that light. Try it out before you get to far with the housing.

-Brett Erskine
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Old August 31st, 2004, 10:01 AM   #62
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THe housing won't contain the battery, just the lamp, mount and power connector.

The lamp gives me enough light for use in events. I'll probably gen up a 14 volt supply when I get the time. Just the addition of a AA battery in series with the 12 volt battery just about doubles the light output.
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Old September 7th, 2004, 02:18 AM   #63
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After looking at the prices and sizes of the lap top Lith-Ion batteries I decided to go back to the original design and just do two 7.2V Lith-Ion camera batteries. This way I dont have to buy any new batteries or charger and if I dont use them for the light on some shot i can still use the batteries for the camera. I really wish I could find a "voltage doubler" or DC to DC converter that will make it possible to use only one battery. In the mean time Im looking into ELECTRONIC dimmers so that I can effiecently dim the LED's and do it without changing the color temp. Found a kit but looking for a small ready made unit. Otherwise the case is done and looks real pro. Small, thin and light weight as possible. I'll post pics when I rework it with the new/old battery setup. Anyone else busy on this project? What have you been doing?
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Old September 13th, 2004, 12:11 PM   #64
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Great LED Website and Luxeon Stars

I just notice this thread and am also a big fan of LED lighting. I didn't notice anyone post up a link to the led museum: http://www.ledmuseum.org/ The guy who runs this site reviews and tests discreet LEDs and *anything* made with LEDs. It is unbelievably comprehensive, most descreets have detailed info including JPEGs of the led's light thrown on a test pattern so you can see the dispersion and any hot spots.
while you are there check out Luxeon Star emmiters. these are very high output LEDs 1 watt and 5 watt models (yes that's right 1 watt), they are a bit expensive (~$20) but have many advantages over using single Nichias or other regular superbright LEDs
Also, I saw somewhere back in this post someone stating that DC-DC converters were not effecient, this is not absolutely true, there are many new ICs designed specifically for driving LEDs that take lower voltages boost to the optimum voltage and provide current limiting, dimming capabilities (through pulsing), and allow batteries to completely used up, because when the voltage drops too low the LEDs will not light and this happens rather abruptly. I think most of these circuits are designed for small LED pocket lights where battery life is a significant concern. Oh also check out the candlepower forums www.candlepowerforums.com (they have been having some problems as of late with their server) Plasmid
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Old September 13th, 2004, 02:11 PM   #65
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Mark, welcome.

Do you have a reference for the LED DC to DC converter chips?
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Old September 13th, 2004, 03:54 PM   #66
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Hey Mike,
Well about 2 years ago I bought ic's(i think they were the LT1932 from linear technologies, discontinued I think, see the lower link, zetex sc310 seem to be popular now) that I thought were 8pin dip packages but for surface mounting to pc boards they were "thin-sot" super tiny things, about 2mmx3mm but they were only a few bucks a piece, could have gotten some board and fabed out some thing, still might, but I got busy doing other things. I just did a quick peek at the candlepower forums and found the link below, $10 for a luxeon driver using similar chips, mounted on a board and ready to go and 1 watt luxeons for $12. I found it in the "Flashlight electronics -batteries included" subforum. Given you interest in DIY I think you'll really appreciate the LED freaks/DIYers there. Search around and you should be able to find plenty of people selling (or directing you to a retailer) everything you could possibly want to put together some kick-*ss LED lighting, and for sure you should pick up a Luxeon Star, you will not believe how small and bright they are, 164,200 mcd@364 mA, versus 11,700@23 mA for a Nichia NSPW500BS, you standard white led.

Anyway the LED driver ics that I bought are somewhere in my house, I got 5 of them so if I find them I'll send you a couple and then all you have to do is get a thin-sot prototyping board from digikey and a couple parts and you can check them out, if you want. I think it's much easier to just find someone who is selling the assembled boards such as the one below... Also be sure to check out the ledmuseum.org, there is a section for links "where to buy leds" as well as tons of links for everything reviewed on the site! Mark


http://www.quality-items-flashlights.com/product_info.php?products_id=91&XTCsid=c43130f4f8fca8ddc8e2da11e4e42d9e

http://www.linear.com/pub/document.html?pub_type=desn&document=295
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Old September 14th, 2004, 09:53 AM   #67
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Nice links, thanks!

I used the Maxim MAX757 for my prototype with 'regular' 6-8000 mCd LEDs:
http://www.maxim-ic.com/quick_view2...._pk/1167/ln/en
I followed one of their application notes, and set the output voltage through the divider at 3.5V. There are newer ICs available, but they don't come in DIP packages, only surface-mount. The IC worked great, but I've yet to find true white LEDs without the blue tint...
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Old September 14th, 2004, 11:22 AM   #68
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Hey Roman,
looks pretty cool. I was quite surprised when I got the LT1932s, which I knew were surface mount but didn't realize they were the size of surface mount resistors, but with 8 pins to deal with!! the ledmuseum has a lot of color spectrum info, you might find some less blue whites digging around there. Mark
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Old September 14th, 2004, 12:00 PM   #69
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Some of the blue from the blue LED driving the phosphor usually gets through. Worse is the uneven color temperature near the edges of the beam. That cant be filtered away.
A modern halogen bulb is about the same efficiency as the best white LED's. I know it's fun to play with the LED's, but they do have some issues.
What was the main motivation to use LEDs , other than the novelty?
-Les



<<<-- Originally posted by Roman Shafro : Nice links, thanks!
The IC worked great, but I've yet to find true white LEDs without the blue tint... -->>>
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Old September 14th, 2004, 12:45 PM   #70
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<<<-- Originally posted by Les Dit :
A modern halogen bulb is about the same efficiency as the best white LED's. I know it's fun to play with the LED's, but they do have some issues.
What was the main motivation to use LEDs , other than the novelty?
-Les
-->>>
Portability. Though I've never researched halogen, I assumed it's much more power-hungry than LEDs. Are you referring to regular R20-type halos?

I also wanted to use LiIon cells from junked laptop batteries (most of the cells are intact when the battery is disposed of), and those don't like high currents.

Lastly - YEAH, it's COOL! Too cool, almost blue. :D

P.S. Mark, I think I see a good one, ETG-5CEWHT-35, thanks to your links:
http://www.etgtech.com/update/products/through_hole.htm
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Old September 14th, 2004, 01:23 PM   #71
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Do some research on lamp efficiency, white LED's are just as power hungry as modern halogens, for the same amount of light.

Don't assume!

-Les



<<<-- Originally posted by Roman Shafro :
Portability. Though I've never researched halogen, I assumed it's much more power-hungry than LEDs. Are you referring to regular R20-type halos?

I also wanted to use LiIon cells from junked laptop batteries (most of the cells are intact when the battery is disposed of), and those don't like high currents.

Lastly - YEAH, it's COOL! Too cool, almost blue. :D

P.S. Mark, I think I see a good one, ETG-5CEWHT-35, thanks to your links:
http://www.etgtech.com/update/products/through_hole.htm -->>>
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Old September 14th, 2004, 01:41 PM   #72
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Halogens have other downsides including the weight of their support systems, the heat they generate and the relatively low lifetime compared to LEDs (OK, that's a stretch).

LEDs can also be dimmed with no change in color temperature (that matters).

For a lot of my event work, I need a light to fill in the shadows and pop the color. I don't need 100 watts as I used before. 42 LEDs with an incandescent color temperature, all in a MR-16 package that will run for 3 days on a very small LiON battery pack is ideal.

LEDs even count higher in the comparison when I have to get on an airplane to attend an event and I don't have to ship heavy NiCAD battery belts and large lamp setups.

The small on-camera Halogens don't work very well in the event environment (unless one counts something expensive in the $200+ price range.

Another benefit? People like to talk about the LED setups and for me, that's an ice-breaker with some of my subjects.
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Old September 14th, 2004, 02:43 PM   #73
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Mike, As I stated, the Halogens need the same amount of power as the LEDs. So what extra heavy support systems are you needing for them? Not batteries.
Bulb life? Not a factor, unless you are doing CSPAN recording!
Variable power? Use three small halogens, and switch them as needed.
But it's way more fun to play with LED's , I know ;)
-Les
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Old September 14th, 2004, 02:52 PM   #74
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Les. Here's why I made my LED light.

1)Because of LED are laid out in groups they can be both directional light AND soft light at the same time all the while not having to be diffused. Dont have to buy a mini chimera which would have cut down the power of the light quite a bit.

2)Dimmable without color change

3)None of the batteries life is used up to generate heat. Talent looks good and is confortable under the light. No more burned gells.

4)Modern LED's can be tungsten balanced and dont have any color problems at the edge of the beam

5)You no longer need heavy battery belts to run your light. Just your camera's batteries attach right to the back of the light.

6)More compact light. 1 inch thick

7)Lighter weight/One piece system on top of your camera allowing for steadicam work

8)The bulbs can handle shock much much better than halogens and are rated to last 100,000 hrs. If one bulb burns out your not down for the day nor is the shot ruined.

9)Lower amp draw compaired to a halogen

10)The same light could be adapted to work on light stands for a ultra compact light kit that works DC in remote locations or AC on set.


Every light has their pros and cons. Halogen for example will allow you to do spot/flood where LEDS would have to be rigged up differently. Anyways hope that helps.

-Brett Erskine
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Old September 14th, 2004, 03:13 PM   #75
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Even if we agreed that LED's and halogens are the same I guess the question that really matters is who commercially makes a on camera halogen light that:

1)Doesnt have a hotspot
2)Dimmable/No Color Shift
3)As Soft
4)As Small
5)Runs of your camera batteries
6)Not hot
7)etc etc etc.

Please tell me where I can pick one up because I would have rather not gone thru all the trouble of building something that already exists.
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