# 180 Watt LED Film, Video, Photo Light 95 CRI - My Chip-on-Board obsession



## snarfer (Aug 9, 2009)

Not exactly a flashlight, but thought some might find it interesting. This is a project I've been keeping under wraps for quite some time now. More than a year actually. Started by building this:















The specs:

16 Chip-on-Board assemblies in two strings of 8. One string is tungsten balanced (2900 K) the other is daylight balanced (5500 K). I managed to get hold of the special high CRI models, so CRI is about 95. Forward voltage is 92.5 volts on each string. Max current is 1 amp. I built the drivers with National LM5022 controller. Mostly I run it off a 24 volt supply, and it gets about 94% efficiency. It will work down to about 17 volts, and up to 32 volts input.

The heatsinking consists of bolting the LEDs to an aluminum box, 1/4" plate, with a whole bunch of surplus Pentium II heatsinks. Had it all hard anodized too. Surprisingly enough, it works great and never goes over about 55 C. 

This has been good for lighting quite a few commercials and music videos already.

Since that project things have progressed:







First of all I had the heatsink machined out of a solid block of aluminum. (That was pretty expensive)






Also made the whole thing a bit smaller. The first one was 12"x12" but this one is 9"x12" instead. The LEDs are a bit closer together.






Also I redesigned the power converter. Now it will take input 12-48 volt DC, 94 to 97 percent efficiency. It is also microprocessor controlled - PIC24H 16 bit controller running at 40 MHz. 

Also it has some different modes. Now the MCU can accurately control the color so instead of just two pots, one for each color, it's possible to have one pot controlling the mix, and the other pot controlling the overall intensity. And there's a temp sensor to keep everything nice and toasty. Oh wait I also implemented master/slave so you could chain a few of the lights together and make them all do the same thing at the same time without need for a lighting board.






And I even put a DMX interface on it. The DMX interface has RDM so there aren't any DIP switches.






Finally I found lenses that would fit the COB arrays. Had a Delrin holder machined for them. They only focus the light in one direction. But that's OK, it's pretty bright already, although it hasn't really got a lot of throw. My favorites are the medium lenses. They have 30 degree vertical spread x 140 degree horizontal, with about 60 foot-candles at 10 feet.


----------



## roguesw (Aug 10, 2009)

Very Very Very Seriously AWESOME!!!!
How many lumens is it?
It looks very rugged and will withstand a lot of use.


----------



## PhantomPhoton (Aug 10, 2009)

Now that's just sweet. Especially being able to power it from that voltage range... makes it highly portable being able to run off of a variety of batteries.
:bow:


----------



## aljsk8 (Aug 10, 2009)

very impressive! What leds are those ive never seen them?

any photos of it switched on?


----------



## dom (Aug 10, 2009)

WOW Very professional looking!
Are you in the commercial industry as well?

You say you can control the color -so there
are RGB arrays in there?

Why didn't you stick with the CPU cooling fins? 
They looked pretty good.

Top job.

Cheers
Dom


----------



## DaFABRICATA (Aug 10, 2009)

Beautiful Designs!!

I'd love to see those lit up! 

Looks to be a very useful set-up!!


----------



## snarfer (Aug 10, 2009)

> Are you in the commercial industry as well?



I am a gaffer. So I rent these lights out to the productions I work on.



> You say you can control the color -so there
> are RGB arrays in there?



It is just the color temperature I can control. No matter what it has to be white. There are warm white and cool white LEDs and the mixture determines the color temperature.



> Why didn't you stick with the CPU cooling fins?
> They looked pretty good.



Well the first light weighs about 15 pounds, and the more recent one weighs about 5.5 pounds. Actually I made some other different versions in between until I finally got everything working pretty much the way I wanted it to. 

CPU coolers work much better than I ever expected though. And at $2 a piece they are a real bargain. I started this project by buying a big box of them and picking out the ones that seemed most useful. They seem to do fine at about 20 watts per CPU heatsink. If you look closely at the first picture you can see it is just 8 heatsinks. 

I spent a lot of time testing the LED temperature and found that the pin fin heatsinks work very well when the light is facing directly down, and directly up. Much better than straight fins. Actually when the light is pointing down it stays about 5 C cooler than when horizontal.


----------



## Tekno_Cowboy (Aug 10, 2009)

About what could you compare the output of this to? It seems like it would be pretty darn bright.

If you were to sell one, about how much do you think it would go for? While cool, it looks like making one of these would be quite an investment.


----------



## snarfer (Aug 10, 2009)

> About what could you compare the output of this to? It seems like it would be pretty darn bright.



If you compare it to some of the current LED lights for film production, like the 1 foot square panels that cost about 2000 dollars, it is the equivalent of 4 of them together. 

Total lumens is approximately 8000-9000. I use it mostly instead of fluorescent fixtures, and very small HMIs. One nice thing is that it hardly ever needs any kind of color correction, so those lumens are generally more usable than with some other lights (where you might have to filter out the green).




> If you were to sell one, about how much do you think it would go for? While cool, it looks like making one of these would be quite an investment.



If it wasn't for the recession I think this project would have been so astronomically expensive that I would have given up on it long ago! When I started I thought it would be possible to make something significantly cheaper than what was out there already. Unfortunately it seems like a full kit would still end up costing well over two thousand dollars.

Obviously the idea here was to make something to sell, but in the end it seems like it might stay a rental item for a while.


----------



## Tekno_Cowboy (Aug 10, 2009)

I thought it would be up there, and I was pretty close with my guess of $2500.

On the other hand, as a replacement for 4 $2000 lights, even $4000-$5000 would be a worthwhile price to pay for it.


----------



## Nos (Aug 11, 2009)

did you use this 48chip emitters? 
http://www.led-tech.de/en/Chip-On-Board-Technic/7.0W-COB-Modules-c_134_136.html


----------



## snarfer (Aug 11, 2009)

> did you use this 48chip emitters?
> http://www.led-tech.de/en/Chip-On-Bo...c_134_136.html



Yes, but I used the high CRI versions. They don't seem to be listed any more. Maybe you need to special order.
http://www.led-tech.de/en/Chip-On-Board-Technic/7.0W-COB-Modules-c_134_136.html


----------



## Nos (Aug 11, 2009)

from the frame to the electronics....professional through and through ........ could go into series right away....:thumbsup:

they could possibly replace the fluorescents 

btw whats its weight?


----------



## snarfer (Aug 11, 2009)

> they could possibly replace the fluorescents
> 
> btw whats its weight?



Yes actually they do replace fluorescents quite well. Because most LED lights don't have enough spread. That was what the idea was in the first place. And then the lenses showed up so that made it even better.

Weight is 5.5 pounds.


----------



## aljsk8 (Aug 12, 2009)

is there any technical info on those leds? the pdf on the led.de site is not very comprehensive - id like to consider these for a 12v direct drive light (12v 12a sla - 12.4 - 12.5v under load) and id like to see the relationship between voltage and current and lumens


----------



## snarfer (Aug 13, 2009)

Yeah that site is kind of weird. I think they are selling them on the grey market or something because they are deliberately concealing the manufacturer name. I can't even find the document you refer to now. I suspect the manufacturer may have some legal restrictions on who they can sell to or where. I don't know.

Anyway I have never pushed the LEDs beyond Vf 12 volts, which got me to about 1300 mA. I think the junction to case resistance is 4 degrees C/watt, if that is any help. Also the relationship between light output and current is extremely linear. I would guess that at 1400 mA, you'd probably get something like 1000 lumens, for the 7 watt cool white models.

If you need more specifics than that you can PM me.


----------



## wquiles (Aug 13, 2009)

Nice project dude - very professional looking :thumbsup:


----------



## cmacclel (Aug 17, 2009)

Very professional! Great Job!

Mac


----------



## TranquillityBase (Aug 17, 2009)

cmacclel said:


> Very professional! Great Job!
> 
> Mac


What he said!!!


----------



## ShortArc (Aug 17, 2009)

Impressive design and meticulous execution. :bow:


----------



## Archie Cruz (Aug 19, 2009)

Neat. Kind reminds me of LED-Z video lights.


----------



## snarfer (Aug 19, 2009)

> Neat. Kind reminds me of LED-Z video lights.



I guess the comparison was inevitable. I tested those lights a few times. Low CRI LEDs, a very tight beam spread, with no adjustability. Total output is a lot lower. And of course no adjustable color temp.


----------



## LEDobsession (Aug 20, 2009)

Very Nice. Ive thought about making something similar to this but instead I made one that suited my offroad needs better.

By the way, where do you get these Connectors?




snarfer said:


>


----------



## rmteo (Aug 20, 2009)

Look for XLR connectors such as these:
http://www.neutrik.com/us/en/lighting/204_293581/DL_Series_productlist.aspx
http://www.markertek.com/Cables-Con...ectors.xhtml?gclid=CJKO6ZSqs5wCFYlM2godJk0gng


----------



## LEDobsession (Aug 20, 2009)

rmteo said:


> Look for XLR connectors such as these:
> http://www.neutrik.com/us/en/lighting/204_293581/DL_Series_productlist.aspx
> http://www.markertek.com/Cables-Con...ectors.xhtml?gclid=CJKO6ZSqs5wCFYlM2godJk0gng



Mmm. :naughty: Just what I needed. Thanks.


----------



## Stillphoto (Aug 21, 2009)

Archie Cruz said:


> Neat. Kind reminds me of LED-Z video lights.



The "lens plate" is more reminiscent of the Nila lighting system if anything, and even that is a long shot.

Cinegear was full of overpriced led gear this year haha.


----------



## snarfer (Aug 22, 2009)

> Cinegear was full of overpriced led gear this year haha.



I was there too. It's really unbelievable the lumens/price ratio. Especially the stuff based on 5mm LEDs.


----------



## spencer (Aug 22, 2009)

I would like more information on the driver solution you used. Is it a constant current or constant voltage solution? Did you design it or did you get a schematic from the datasheet or something?

Thanks,
Spencer


----------



## snarfer (Aug 22, 2009)

> I would like more information on the driver solution you used. Is it a constant current or constant voltage solution? Did you design it or did you get a schematic from the datasheet or something?



I designed it. It is constant current. Although I did start with some datasheets, the power output is far in excess of what the IC designer had in mind. I spent a lot of time doing simulations in ltSpice over and over again. I also use ASCO, which is an optimization software that is based on some fancy mathematical algorithms. It basically runs the simulation over and over again for days until it finds the optimum solution.

The first prototype boards had a nasty tendency to catch on fire, and I got some help from the engineers at the IC manufacturer to fix that problem. 

Actually the driver is so overengineered now that it could probably handle 400 watts output. I had to add a lot of extra circuitry to make it possible to boost from 12 volts to 92 volts at 95% efficiency. There are nearly 130 parts on the board. I submitted a patent application for some of the dimming techniques I used.

At some point I plan to make some different versions of the converter available for sale. But for now I am spending my time trying to figure out how to make more of the lights themselves without going broke.


----------



## spencer (Aug 22, 2009)

I would be extremely interested in one of these drivers. It sounds like it would work in an automotive application (what I had in mind for it) to run a couple hundred watts of LEDs for axillary lighting.


----------



## 65535 (Aug 22, 2009)

That's amazing, I want it.


----------



## snarfer (Aug 23, 2009)

> I would be extremely interested in one of these drivers. It sounds like it would work in an automotive application (what I had in mind for it) to run a couple hundred watts of LEDs for axillary lighting.



Let me know what exactly your requirements are. You can't be the only one who wants something like that. I think for an automotive application you wouldn't need the microprocessor and all the networking features though. You might not even need dual outputs, depending on what LEDs you're running.

As it exists now the driver would probably be perfect for running about 6 MC-Es per channel in series configuration (6 x 4s1p). I guess you could run 12 per channel in 2s2p configuration, but you might lose a little efficiency. I've never tried it because MC-E CRI is too low for my application.


----------



## Paradime (Sep 10, 2009)

Great job on the build! Many video lights simply turn off unneeded lamps instead or dimming. Any thoughts about this practice?

I am planning on building my own lights and wanted to stay with 3w units in the 4-5.5k range with a cri of at least 90+ any suggestions?

Sean


----------



## snarfer (Sep 10, 2009)

> Many video lights simply turn off unneeded lamps instead or dimming. Any thoughts about this practice?



Well it wouldn't really make much sense for LEDs I think. But it works for tungsten.



> I am planning on building my own lights and wanted to stay with 3w units in the 4-5.5k range with a cri of at least 90+ any suggestions?



I think it will be difficult to come up with a cost-effective solution in 3w LEDs with cri 90+. Sharp is making some LEDs that are available on Mouser, but expensive...


----------



## Bilway (Aug 13, 2010)

Yo Snarfer,

that's really an awesome project of yours. Repect!!
Do you have some lit images of your smoothly highlighted kitchen table for us? - Or maybe a look into the light with the MCOBs running at low current?
:thumbsup:

Cheers, 
Andy


----------



## Illum (Aug 8, 2012)

This thread really deserves a  for the eye candy it has to offer:naughty:
I've been trying to imitate it for ages, but with a fixed color temp


----------

