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Sandwich recipe?

StoneDog

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Hi Everyone,

Several years ago I put together a few sandwiches using the older madmax, etc converters and various Luxeon emitters.

Apologies if I missed a FAQ or sticky, but is it still possible to make sandwiches and if so can they use the newer emitters?

Thanks in advance!
 

StoneDog

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Str8stroke, Dat2Zip's store points us back here...

Wolfy1776, the MadMax was a series of more efficient converters that Dat2Zip offered a while ago.

I guess it has been 7 or 8 years at least since the idea of a MagLite AA drop-in module so perhaps this is all ancient history and nobody builds them anymore. But, he still lists the parts, they are in stock and the older Luxeon III emitters (still in stock) will get the job done. I think I'll order a few for a rainy day project.
 

more_vampires

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Sandwiches using mad max sandwiches? Would those be Vegemite?
Rockatansky went for peanut butter and honey on whole wheat. :)

Just curious though, what's the interest in the old Luxeon? Efficiency and output have been jacked up big time since then.
 

StoneDog

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Rockatansky went for peanut butter and honey on whole wheat. :)

Just curious though, what's the interest in the old Luxeon? Efficiency and output have been jacked up big time since then.

I've been out of the hobby since, well, since the Luxeon III was eclipsed by its competitors. These PCBs could be used with Luxeons and BB or MadMax converters to create minimag drop-in "sandwiches", hence the name of Dat2Zip's shop.

What I don't know is whether any of the newer emitters can be used with the PCB I mentioned. Luxeon's cathode tab and base are both grounded, but not sure it is the same with anything else.

...which is the reason why I posted here. Doesn't seem to be as much traffic here. Perhaps people just aren't building these DIY MagLite AA drop-ins anymore?
 

more_vampires

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Looking at Madmax specs, 700ma with max Vf out@ 3.1v, I'd think any emitter that's cool with that should work. As efficiencies have increased since the Luxeon days, it'd offer higher output at the same old 700ma.

http://theledguy.chainreactionweb.com/product_info.php?products_id=181

XPL HI, for example:
http://cree.com/LED-Components-and-Modules/Products/XLamp/Discrete-Directional/XLamp-XPL-HI
Typical Forward Voltage 2.95 V @ 1.05 A
It maxes out at 3 amps (10watts,) so 700 ma (1.5watts) is a walk in the park for this emitter. 2.95v and 3.1v is close enough to be a wash, afaik. XPL HI maxes out on voltage at about 3.3v so no worries there.

700ma on XPL HI would drive it very convervatively. Keep in mind with adequate thermal considerations, this thing can go to perhaps over 220% of a conservative drive level. Maybe. (source: cree data sheet page 7)

This would be a pretty underdriven setup so it shouldn't get hot at all.

XPL HI is 200lm/watt@350ma. 1.5 watt on the madmax could theoretically give us 300lm or so. That board would definitely be a limiting factor as we'd be driving a 3 amp emitter at only 750ma.

Please keep in mind that I've not tried an XPL HI on a setup like this, so I could easily have made a mistake or overlooked something. It was just a convenient example. Luxeon III, 45lm/watt? 200lm/watt beats the pants off of it, provided that the example emitter works.

If I've missed something or slipped up, let's talk about it in that friendly CPF way. :)

Edit: I see the BB Nexgen supports up to 1 amp, would be a better choice than that Madmax board. (assuming we're trying to drive an XPL HI)
 
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more_vampires

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That's a whole lot of numbers, it's really easy to slip up especially when it's shooting from the hip like this. :)
 

StoneDog

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The original sandwich PCBs were 14mm in diameter. 10mm is too narrow for incan minimags.

The big question then is whether the XPL HI has a common ground with its base and cathode since the PCB grounds to the minimag body.

EDIT: I didn't see the MadMax anywhere on the Shoppe's site, I think they are long out of production. A BB750 driving an XPL HI would be 400+ lumens it sounds like. How do they compare size-wise to a Luxeon III?
 
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more_vampires

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The big question then is whether the XPL HI has a common ground with its base and cathode since the PCB is both ground to the minimag body.
In the Luxeon, the base wasn't electrically neutral (luxeon III datasheet page 2) so you wanted to insulate that and wire to each lead on the LED, right?

XPL HI is the same way, powered by discrete wires, except you reflow solder the thing to the MCPCB. (Cree Xlamp HD Discrete LED Design guide page 5) We had to insulate the Luxeon III, right? Sorry, it's been a LOOOOOONG time since I thought about the Luxeon. Cobwebs! :)

Maybe I'm confused, what's the problem now?

The original sandwich PCBs were 14mm in diameter. 10mm is too narrow for incan minimags.
Well, it'd still fit with a bushing, right? I'd have busted out the calipers and measured a minimag, had I one handy. :(

It'd be best to use what fits, yes.
 
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StoneDog

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In the Luxeon, the base wasn't electrically neutral (luxeon III datasheet page 2) so you wanted to insulate that and wire to each lead on the LED, right?

XPL HI is the same way, powered by discrete wires, except you reflow solder the thing to the MCPCB. (Cree Xlamp HD Discrete LED Design guide page 5) We had to insulate the Luxeon III, right? Sorry, it's been a LOOOOOONG time since I thought about the Luxeon. Cobwebs! :)

Maybe I'm confused, what's the problem now?

No problems, just questions...

Cobwebs for sure, I don't know the last time I built one of these things. My son (now in college) asked if we could make one for the mini-mag he keeps in his dorm room. So, that kicked off this whole thing and now I'm obsessing a little.

If memory serves the sandwiches used arctic silver(?) to fasten the emitter to the board. Or maybe that was just for the heat transfer and the solder fastened it to the board? Either way, I think the board provided a common ground to both the cathode and the rear of the emitter, so this differs from your recollection? The minimag reflector was then modified to fit around the dome of the Luxeon and it would press the whole sammich away from the lip of the minimag body to open the circuit and turn off the light. A luxeon iii replacement would need to fit inside the minimag's opening and have a structure around the dome that could handle the force required to push the whole thing away from the lip.

I took a quick look at the very impressive XPL HI and there is no dome. Since I'm a garage hack with no formal training :D the reflow soldering concerns me a little. Seems to be common to most of the really nice Cree's... I just pulled the last sammich I build (madmax lite with lux iii, bin long forgotten) and I used a copper disc for the top board. I wouldn't be able to do that with the cree.

Well, it'd still fit with a bushing, right? I'd have busted out the calipers and measured a minimag, had I one handy. :(

It'd be best to use what fits, yes.

Yes although this is starting to feel like it's not really worth the effort.
 

StarHalo

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although this is starting to feel like it's not really worth the effort.

I absolutely support our builder community, and your son is lucky to have a dad who would put something together for him, but there's the possibility that he's going to show off his new toy to someone who has a Minimag from Wal-Mart, only to find they have similar output.

If you want a small light with big output on safe batteries, the current Zebralight SC5 pulls a tested 575 lumens from 1xAA.
 

more_vampires

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If memory serves the sandwiches used arctic silver(?) to fasten the emitter to the board.
Okay, that I do remember.

Artic silver has a couple of products.

One is a thermal paste with no adhesive ability, it will stick nothing. Great thermal transfer.

The other is a thermal epoxy that DOES stick stuff, plus thermal transfer. "Artic Silver Epoxy."

XPL HI design guide states that while reflowing/affixing the emitter you're not to exceed 2 kilograms of pressure so you get a good bond and don't break anything.

Never tried attaching an emitter using the AS epoxy, I usually just buy a MCPCB star with the thing already on it. You don't have to reflow your own emitter.
 

StoneDog

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Well, thanks for the input everyone. I'm not going take on this project, it's just not worth the effort. :(
 

StoneDog

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You could just buy an led drop in for minimags?

Very true, or as StarHalo pointed out I could just buy a LED minimag. The point of this was to have some fun in a DIY project but, again, not much point using emitters (and techniques) from 8 or 9 years ago. Progress is a good thing. I'll just have to find a different project. :D
 

yazkaz

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...Perhaps people just aren't building these DIY MagLite AA drop-ins anymore?
I still use custom pills on MagAA mods, but spec-wise they're not very efficient. For instance, my current EDC MagAA has a GD1000 driving an SSCP4 (U3 flux) and powered by a single 14670. Decent output but suitable for very short periods only.

Meanwhile another backup MagAA has an NG1000/SSCP4 (U2 flux) pill inside. With lithium primaries (2xL91 AA) output is quite satisfactory as well.

Just recently I've had a local mfyer build two XPG2/GD1000 pills. Very nice output (per mfyer claims) but again runtime is expected to be quite short (25-30 mins max?).

BTW all modules built around a copper tower heatsink designed by some Japanese member here some years back. That heatsink has since been discontinued but I've since had clones made for my own use. If anyone here is interested I may consider having some more made in the future (unit price won't be cheap though).
 
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