Heheh yes it is. I never throw something like that out.. it's just one Ginormous heat sink, solid aluminum, probably a good two pounds.. with those nice vanes on the back and even a hollow interior (where I am hiding much of the sloppy wires. I see a heat sink like that, I grab it.
Remember my big old rack mount Telco power supply? It was time to sacrifice her, she's just too big and unweildly. But why would I do that, you ask? Simple. Inside of the twenty five pound steel monster is an array of Volgen industrial power supplies, each one with it's own heat sinking and case. I need 16-18v @ 3A for the fifty watter.. and one of the PS modules is a 24v@5A model. With the voltage adjust turned all the way down, I get 17.8v - Perfect! With the addition of a 2n3055 based current limiter set up for 3A- we are good to go. One question, if anyone has used them- there's an enable on the PS, open circuit the PS is on, closed circuit the PS is off. I am just planning to use a MOSFET like the others, but I am wondering if there's any advantage to using that enable circuit (prolly not).
After drilling a couple mounting holes, I soldered some leads on the 50watter and slathered it with compound, and screwed the beast right in the middle of that LanCity cable modem case.. and switched it on. I was foolish enough to actually be looking nearly directly at the LED from a foot away when I turned it on. I'll say this.. 3500 lumens of warm white LED is BRIGHT. Like afterimages for a good five to ten minutes bright. With that huge heat sink, I am able to place a finger right on the emitter and it's only comfortably warm. The resistors in the current limiter were far hotter. I actually have to return to that limiter circuit, because I substituted 240 ohms in the circuit for 220, and when metered out, it shows that the current actually is limiting around 2.25A while the emitter wants 2.5-3A. Not sure how much more light I can get for another 500ma, but I plan to find out. Since output isn't linear to input, I figure I am maybe losing a hundred lumens or so without that extra quarter to half amp.
So, I am putting together the MOSFET for this one this morning.. should be ready to start UberBlinken later today.
The current capacity of the system:
8x 3w Warm White, 200 lumens each, for a total of 1600 lumens
1x 10w Cool White, 1000 lumens
1x 50w Warm White, 3500 lumens
This gives us a total of 6100 lumens or thereabout, for a power load of 84 watts plus a little overhead for the regulators. With this mess hooked up, I am going to try to take a photo or two with it later today, just to see how it turns out. Overall, getting 20 lumens per watt isn't very efficient.. but I am not really looking to make this efficient. I want it BRIGHT, and able to be switched in the range of tens of microseconds. As I am trying to emulate a Xenon strobe in a way, I want my pulses to be at least as short.. Xenon tubes typically fire in the range of a millisecond duration.
I still have six more of the three watters, plus another thirty 1w discrete LED's, just about another 50 watts.. but I am going to hold off adding more until I play with it as built for a little bit. If I can get a usable image with the power I have at the moment, I have possible other nefarious uses for that batch. That being said, I originally set out for an arbitrary 10K lumens, and that mess would bring the total close..
However, I am now not powering up the system until it's facing the wall-- it's painful to look at, downright blinding...