Switch emitters on a BB400?

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robk

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I have an extra BB400 (white) and I'd like to put a red emitter on it. Do the Reds take the same voltage & current, or will I see a big puff of smoke? The white emitter is not epoxied to the pcb, so it will come off easily.
Thanks,
Rob
 
I'm no expert on the specifics of an LS (Never even set eyes on one yet), but given that the operating chemistry is the same as an "ordinary" LED, the reds will have a far lower Vf requirement, so unless that can be altered on the BB, you'd probably cook the LS. I could be wrong though, as I said, I'm no expert.
 
That's my concern. I have parts coming in for a few more ZLT drivers that I can set the current on while assembling. The BB400 is pre-set and cannot be changed. But you know how it is, you get an LED in the mail and you gotta see it lit NOW!
Rob
 
I thought BadBoys were constant current. If the red LS is spec'd for 350mA? (and will tolerate being overdriven to 400), wouldn't the BadBoy just lower its output voltage accordingly to achieve the 400mA?

Larry
 
[ QUOTE ]
tvodrd said:
I thought BadBoys were constant current. If the red LS is spec'd for 350mA? (and will tolerate being overdriven to 400), wouldn't the BadBoy just lower its output voltage accordingly to achieve the 400mA?


[/ QUOTE ]

Only if the Vf of the Luxeon is higher than the battery voltage feeding the BadBoy. If you have 3V of batteries, and the Vf is 2.5 volts, I believe you could see a bit more than 400ma. I'm sure dat2zip will let us know /ubbthreads/images/graemlins/help.gif
 
Well, I'd be powering it with 2 NiMH cells, 2.4 ~ 2.8 Vdc. I just tried it on a ZLT+ that was set to 400mA with 2 NiMH's and a white emitter, and the red one pulled 400mA also (~40mV across a .1 ohm current sense resistor). But I think the BB is different!
Rob
 
[ QUOTE ]
trailstoride said:
[ QUOTE ]
tvodrd said:
I thought BadBoys were constant current. If the red LS is spec'd for 350mA? (and will tolerate being overdriven to 400), wouldn't the BadBoy just lower its output voltage accordingly to achieve the 400mA?


[/ QUOTE ]

Only if the Vf of the Luxeon is higher than the battery voltage feeding the BadBoy. If you have 3V of batteries, and the Vf is 2.5 volts, I believe you could see a bit more than 400ma. I'm sure dat2zip will let us know /ubbthreads/images/graemlins/help.gif

[/ QUOTE ]

This is a good point. Whatever your Vf you must remember that the BB400 must operate as a stepup, i.e., the battery voltage should be lower than the LED Vf. In practice, the battery voltage can exceed the LED Vf [at 400mA] by about 0.3V before current begins to increase. This is due to the 0.3V drop of the schottky diode that is effectively in series with the LED.
 
Well, I removed the white emitter and put the red one on the BB400, and no smoke. It draws about 410mA, should be OK. One interesting thing I noted about the BB400- when you remove the emitter, you find a small 1/4" or so isolated circle of tinned copper where the slug rests. I don't see how the heat transfers to the aluminum body of the Mag. My home-made emitter boards conduct heat pretty well (but the slug is grounded in my setup - not recommended). Here's what my emitter boards look like:
emitterboard.gif


Rob
 
robk,

Sounds like you got one of the few rare exceptions. I had made the circular isolated board for someone that was going to make the board out of ceramic and they had asked I had the center portion isolated. While this is not the optimum, I think for the BB400 and the Madmax, the thermal properties should be OK.

As for the Red Luxeon. You are probably in direct drive and am pumping more than 400mA to the LED. But, if Vin is not more than 0.6V past the Vf, you are somewhat safe. Exceeding this will start applying serious overdrive to the output. The output diode is rated for a good 1A and then some.

Getting back to your board. I had ordered some of these by accident and due to backorders I ended up using these for that particular batch. I don't believe there were more than about 50 some modules that used this particular emitter board. All others are full solid tinned copper on the top.

Wayne
 
How difficult is it to change emitters on a BB400 module? I have no problem with miniature soldering, that shouldn't be much of an issue...I'm more concerned about alignment and heatsink compound. Is Arctic Silver / Arctic Alumina required, or will common zinc oxide heatsink grease work? Is the best way to center the emitter to eyeball it?

As for driving the red LS...you could always get a little less efficient and add some resistance in series with your batt supply. Just enough to drop a few 100mV at 400mA.

Last question...I promise /ubbthreads/images/graemlins/smile.gif...has anyone tried putting a HD LS on any sandwiches?
 
Wayne,
I guess I got a "Special Edition"! Works fine, the aluminum body does warm up a bit on this module, I was just surprised to see the circular "gap" in the copper. I thought it was to electrically isolate the slug from ground.

JSW,
It's easy to change out the emitter. On the one I did, the old emitter "wires" were trimmed to fit a few mm into holes on the board. Heat them up and slightly lift with an xacto blade, going from one electrode to the other and back a couple of times until it falls off. The emitter is "planted " pretty deep - I thought it was just soldered to the surface, but it does go into the holes. Clean out the holes with a solder sucker and pop a new one in! Centering is almost automatic, you can push it around by eye to get it pretty exact. I used some generic heat sink compound and it works fine. And, the red LED is a HD - little strange beam from the NX05, so I put a NX01 in it and it seems to be usable and very bright.

Rob
 
Hey! You can solder? I need more solderers at my place...

Just kiddin. There are four alignment holes that surround the perimeter of the emitter. You can visually use these to ensure the emitter is centered. Without them, it was a ***** to see if the emitter was centered. Good thing I added those...

When you are done soldering, inspect the perimeter carefully. Remove any excess solder flux that might be there and any other debris. Also, while you are at it, now is a good time to look into the flashlight tube and clean out the mating contact surface of the battery tube. I use my exacto knife to clean the top perimeter of the module. I hold the edge of the blade flat and parallel to the surface as I scrape it. I'm pretty good now where I don't remove any of the tin plating. Chemical cleaning will leave a residue and this is not desireable.

I can only suggest that you use Arctic Alumina. Regular heat sink compound will make the emitter run hotter than normal and while it will still work, the photon output is reduced since the emitter is hotter (Less efficient).

Wayne
 
Yeah, I need to buy some Arctic Alumina. I did buy the arctic 2-part epoxy stuff in the little syringes, which I usually use on my projects, but I didn't want to permanently mount this red LED, in case I didn't like it.

Any tips on cleaning the inside lip of the flashlight body? I was thinking of grinding a relief in an xacto blade to reach in from the front and gently scrape.
Rob
 
the main thing to clean out the battery tube is just the debris. I've noticed that many tubes I look into have black or darkened something. Usually some kleneex stuff up there with a long pen or pencil will get the stuff out. Again, unless you use a good ultrasonic cleaner with proper chemicals, I would would discourage using alcohol or any other chemicals since this will disolve many things and leave a residue that would make things worse.

Having a 10X eye loupe, magnifier or some other way to inspect the top of the module for any flecks, dust or debris is helpful.

If some soldering spills over to the perimter, then, it needs to be solder wicked away and scraped down flat.

Let me know if you try the relief and how well it works.

Wayne
 
[ QUOTE ]
dat2zip said:
You are probably in direct drive and am pumping more than 400mA to the LED. But, if Vin is not more than 0.6V past the Vf, you are somewhat safe. Exceeding this will start applying serious overdrive to the output. The output diode is rated for a good 1A and then some.

[/ QUOTE ]

So when Vin exceeds Vf, the module goes direct drive, eh? Didn't know that... Is that true for the MM also? Could this hurt the converter, or does it just provide more juice to the LED? I know the LS's can handle a pretty good amount of overdrive, perhaps decreasing their life expectancy, but am wondering if too much Vin would hurt either the BB or MM converter? Not that I would do this, just wondering.
 
LEDmodMan,
I've stuck in a Copia in a E2 body into a McLux head that's running with a BB400 Q3L, and believe me, it's BURNING... It is definately in direct drive. Within 4-5 minutes, the entire flashlight is very warm, and 10 minutes or so into the burn, it's hot... So pretty much if Vin is larger than what the Q3L's Vf (3.4V), the regulation is off and it's DDed...
 
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