Wow.
I wish there more threads like this. 24 XM-Ls . . . farking awesome.
farkFoy
Really great :)
Cant wait for the result!
Fritz
Sorry I've been gone for a while - Life got busy, as life tends to do once in a while..
dthrckt, Thanks very much for the 'wow' :) Thermal Analysis is quite amazing today - My suspicion is that the big guys don't do it because they don't want to know :)
The Solid Modeling was done with SolidWorks 2011
Thermal Analysis was done with Solidworks Flow Simulation 2011.
CNC CAM was done with Mastercam X4.
Circuit board Schematic Design was done with Orcad Capture CIS
Circuit board Layout/Route was done with Cadence Allegro 16.3
More to come!
PPtk
Had a few minutes the other day, so I threw together a schematic and layout for the circuit board that will carry the LED's and the drivers. I may consider sharing this once it's been debugged and proven to work.
Here's what went out to be fabricated. Should have it back in three or four days.
Overall, the board has 1,678 vias - the vast majority of which are strictly for helping move heat away from the LED emitters and into the enclosure.
The board was designed for 30 Amps of current (Max current with 24 LEDS at 3A each is about 20 Amps) with less than 0.05V of drop across the 14 inch length. Each group of 3 LEDs will be infinitely and independently variable in brightness. PWM Frequency of the constant current drivers will be 500 KHz, so there will be NO audible hum or visible blink. With the particular N-Channel MOSFETs and ultra-fast recovery Schottkys that I've picked, efficiency of the driver should be 92.. maybe 93 percent. Not bad..
PPtk
Circuit boards showed up yesterday. They look great. I'll be putting parts on and testing the circuits this week - should be making light by next weeekend.
The enclosure goes monday to be anodized.
2ish weeks and I should have a fully completed light!
Man, that's lookin' bad ass.
Pilot -
This project is so awesome . . . I can't wait to see this on the front of your Jeep. Regarding throw; would you say each triple approximates say, a Dry or Sky Ray in size/reflector depth/configuration. Will it be, basically 18 Drys and 6 triple XP-Gs driven to within an inch of their collective lives?
Sorry if I missd it . . .
Foy
Impressive. I'm really looking forward to this thing completed. :)
Absolutely brilliant project, looking forward tot his perhaps becoming available as a kit.
Awesome work! Did you learn or study something related to this?
wow you are a perfectionist also a dedicated board
but hey lazy ass you promised 2/3 weeks! ...kidding xD
Foy,
Thanks very much for the kind words. I'm happy that you are enjoying my project.
The optics are a LITTLE smaller than the SkyRay/TrustFire/DRY - but they're TIR, not reflectors. In my limited experimentation with them, the beam profile is quite similar to my trustfire 3-XML. The hot spot is beautiful and is hard to even define - it just rolls off into very useful spill.
I believe the Trustfire and the Skyray are actually driven less hard than I will be driving my emitters. I'm giving them TRUE current-controled 3A each. I'm not sure how hard the DRY is driven, but I think I recall it having a Direct-Drive mode where it's probably getting more than 3A per emitter.
For the moment, I'm going to populate the board with all XM-Ls (24 of them), as I don't believe I'm going to need the additional throw from a few XP-Gs. There will just be so much light coming out the front of this thing that I don't believe its going to matter, and I'd rather have the raw lumens of the XM-L's than the slight increase in throw from the XP-G's with the resulting fewer total lumens. I'm also more confident that I can get the tint to match using all the same emitter type.
PPtk
I still haven't made my mind up about this.. Depending on how it all comes together, I may sell the completed units. I'd probably be willing to sell it as a kit as well, but frankly, it would be really difficult for most people to put together at home. The circuit board uses QFN parts.. 0603 parts.. and even the emitters aren't easy to solder. I solder QFN parts by hand all the time, but I've been doing this for a long time - a hobbiest doesn't stand much of a chance of soldering a QFN..
What I might consider is selling the circuit board with all the parts already on it as part of a 'kit'.. The only problem with that is that the unit is 90% built at that point.. kind of defeats the purpose of the word 'kit'.. Still pondering..
PPtk
THANK YOU!
I'm an electrical engineer, and all of us EE's are forced to be mechanical engineers whether we want to or not..
PPtk
Oh, I'm far from a perfectionist... Too many years of getting things done, not getting things perfect. Perfect comes at the cost of time - not a luxury I usually have.. I always strive for 'as close to perfect as I can get in a reasonable time period'. Thank you though, I'm proud of my project - perfect or not.
I only wish it was me being lazy that has held this project up a bit. I can't tell you how much I'd like to sit on a beach with a Johnny Walker Blue and have people point and call me lazy :) Unfortunately, what has held this project up has been work - I've been absolutely buried the past month or so.
It's coming though - results soon!
PPtk
Ahhh . . . TIR, so that's how you're getting the throw you need. And, you're right about the Dry; mine pulls near 5 amps at the tail cap - don't know how much each emitter gets . . .
alotFoy
5 Amps? Holy crap. the DRY has 3 18650's right? If it does, that means that each emitter is getting 5 amps! (subtract a LITTLE for driver inefficiency, but it's a few percent at most)
I can't believe XM-L's are not just blowing up with sustained driving at 5 amps! It's also pointless, since past about 3.5 amps, XML emitters convert almost all of that extra power to heat, not light...
PPtk
P.S. - The driver circuitry I designed could easily support driving each XM-L to 5, even 6 amps.. Once I have everything debugged and working, I might crank them up to 4 amps per to see if it makes any (visible) difference.. It would also be trivial to put a few SST-90's in place of some XM-Ls. The only thing I would have to do is change the inductor and double the output capacitance (easy), and then my driver could happily give 9 amps to each SST-90 :) Heat would be a major problem though. It would be fine for short bursts, but there is no way that my enclosure could dissipate 720 watts of power without a shit-ton of airflow. If one needed a ton of light during a hurricane, though, it would be perfect :)
Many Drys (including mine) have a 20 second step-down UI. 20 seconds in "turbo" mode and it steps down to high and you're right; Match did a chart that shows the gains above 3.5 amps are small/don't justify the heat/emitter abuse. But, with 3 x 18650 the Dry does indeed feed each emitter with that much current.
Since there's no free lunch when dealing with extreme output, I guess that's why I'm so impressed with how you've addressed the necessary trade-offs.
amazingFoy
That makes more sense.. 20 seconds worth of 'turbo' mode can be dealt with thermally. Much beyond that, you'd be carrying a small toaster that happens to output a bit of light :)
As for addressing the trade offs, well, I realized many years ago that life is a compromise. Engineering a light such as this is no different - a set of compromises that work well together. Hopefully I have chosen well, and none of the variables turn out to be different than expected - but only time and 240 watts of input power will prove that :)
The other cool thing about the driver I worked up - it will take from 10V to 120V input. When I'm testing, I can run the thing from a 100V DC Power supply, and it will only draw roughly 2.4 amps - this way, I can test and debug without having to use massive input wires.. 18ga will be fine. Once in the vehicle, I'll be using 6ga to lessen the voltage drop. I designed the driver to have the highest efficiency at about 14V - typical of vehicle with the alternator turning.. At 100V, it will make a little more heat, but we're talking about a watt or two - nothing substantial compared to heat from the emitters.
Thanks so much for your kind words - I just might have to send you one of these to 'review' :)
PPtk
LOL
Oh yeah . . . would look killer on the front of my Passat.
And, as for the SST-90s . . . a big die that needs a lot of juice to perform and I doubt there would be any noticeable increase in brightness. I also agree that there would be little if any advantage using a few XP-Gs, other than less light. Once it's up and running, I predict you won't be saying, "I wish they threw better." There's going to be some reach for sure but I suspect aiming won't be an issue. It will basically be this insane horizontal of lightning from a distance and since it's flat, it might illuminate the shoulders of the road pretty well.
Actually, the more I consider aiming, the less sure I am about what you'll see from behind the wheel. I'm a novice so, this is probably all redundant to you. As is everything on the base being able to withstand over 170 degrees F sustained. Is that about right? A little high, perhaps?
Sorry - just can't seem to stop thinking about this . . . pretty damn awesome.
Foy