# Want to use Phillips 5761 bulb- dont want blown bulbs: how to set up?



## GarageBoy (Nov 29, 2009)

What is a nice, easy to set up way (minimal soldering) of building a 5761 based light? Would like to go with either 18650s, AW IMR C cells and AAs, in that order of preference. Might use AW's soft starter (wish there wasn't the dimming modes), unless there is an easier way. Would like to keep internal resistance to a minimum. 
Thanks!


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## leukos (Nov 29, 2009)

If you used 2x A123's or LiFePO4 batteries I don't believe you would need a softstart at all. Is that an option?


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## ^^Nova^^ (Nov 30, 2009)

Yeah, LiFePO4 cells won't blow the bulb. It won't be a bright as possible, but still plenty bright.

Batteryspace has some available in differing sizes.

Deck out a 2D mag with a KUI socket and you should be good to go (along with reflector and lens swap).

Cheers,
Nova


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## GarageBoy (Nov 30, 2009)

What is the proper charger for them? Thanks


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## ^^Nova^^ (Nov 30, 2009)

To be honest, I am not entirely sure. I have heard some reports that regular Li-ion chargers work fine, although it seems setting the charger to 4.1v termination not the normal.4.2v is better. There are proper LiFePO4 chargers around though, this may be a better option.

I would find out a definite answer before purchasing anything though.

Cheers,
Nova


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## GarageBoy (Nov 30, 2009)

Is there a switch with soft start only? (I'll get the AW if theres no other way)
Now to decide if I want the compact 2C size or the 2D size


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## luckybucket (Dec 1, 2009)

I have a 2c 5761 powered by two 26500 lifepo4's and it will never blow the bulb. The problem is it doesn't even drive it to specs. I measured 6.4v at first turn on and 5.7 after 1 min. I didn't check to see where it stabilized because I was so dissapointed already. This bulb is really shines when overdriven and I'm already planning a build with a regulator to push it to the max.


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## mudman cj (Dec 1, 2009)

There is the *JM-PhD-D1 PWM Hotwire Regulator.*

Other than that you could try using an NTC. Northern Lights did some work with them and found that there can be a lot of variation from component to component. Still, it has been done. Of course, there is always a power resistor. They waste energy, but they work!

If you use LiCo 18650s you really don't need soft start, but you can't use protected cells either because the current draw is too high and trips the protection circuit. You would have to use high quality cells like LG.


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## GarageBoy (Dec 1, 2009)

If I was going to use 18650, I'll do IMR, which means POOF
I wish I could install a second switch that cuts in a resistor to start it before giving it full power


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## mudman cj (Dec 1, 2009)

That is sort of how NTC's work. They offer more resistance when they are cold and the resistance drops to almost nothing when they are hot. There are some threads on using them, but most of them were for AW C cells (LiCo) with the 5761. I would contact Northern Lights for recommendations pertaining to the use of IMR 18650s with the 5761. This may be one of those situations that also requires the use of a resistor in combination with the NTC to get it working, but you would spend a lot less than on a regulator or AW soft start, it would not have a delay like the AW switch, and it would be pretty efficient too. You already said runtime was not a concern, so I assumed a resistor solution was acceptable.


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## GarageBoy (Dec 3, 2009)

Runtime is not a concern, though I do want maxiumum "safe" brightness


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## GarageBoy (Jan 26, 2010)

Anyone else using LiFePO4 cells? Curious about how bad the under drive is

So if I use IMR 26650 cells in a C [email protected], it'll be a tight fit or will I need it bored out?
If I use 18650s, do I need to sleeve the batteries?
In both cases, I'll need to mod the tail cap spring in some way or form, right?


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## swampgator (Jan 26, 2010)

GarageBoy said:


> If I use 18650s, do I need to sleeve the batteries?
> In both cases, I'll need to mod the tail cap spring in some way or form, right?


 
You don't _have_ to sleeve 18650s, I've got one without a sleeve. I'll probably end up sleeving all 3 of mine before it's over, if for no other reason than to keep the cells from rattling.

For 2 18650s you'll need to deanodize the tailcap. I used a dremel with a grinding stone. All you have to do is work it til you see bare aluminum. Then you'll need something to make contact between the tailcap and the batteries. I've used a minimag tailspring for my lights. 

I don't have anything currently running a 26650 so I can't answer about them.


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## GarageBoy (Jan 27, 2010)

oops, I meant 26500 IMR


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## Conte (Jan 27, 2010)

Love the IMR26500, but won't fit in a MagC.


2x18650 is a typical setup for a MagC. And as you can get the AW p26 cells, you can get more capacity out of them then the IMR cells.

I would recommend the WA1111 or ROP bulbs.
Both are configs you can run in a 2C with the 18650 without an Incan Driver and without 

Also, there are more reflector options for the Rop and 1111.

Sleeving the batteries is recommended, and really easy. You can make a decent sleeve out of papertowel tube and electrical tape. 

THIS CHART will give you a good idea what a 5761 can handle. 
Seems you'll gain a good 700 lumens going from Lifepo4 to Li-ion.

As the bulb flashes at 7.9v you'll def need a softstart to run it off 2 Lions. And at 5+ amps it will exceed the P-26 output ability.
Are you sure you want to go 5761, it's a much more complicated build? 
A Rop54 High will rival its output, and according to THIS CHART you _*SHOULD *_be able to build one with the P-26 cells and without the need for a softstart. 



If you are willing to buy a softstart, you could go Mag85 in a 2D with 3xIMR cells. This would be the best config in my opinion for that output level. And I've personally tested it. 


Within the next days I'll be writing up a Rop/11 tutorial, and a tutorial for easy sleeves.


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## Benson (Jan 28, 2010)

I dunno how much you're after a hot Mag61, and how much you're after the experience of building one. If it's the former, Northern Lights has an absolute steal right now.

The other option for a 5761 in 2C is the DX 25500 -- actually capacity is 3Ah or so, so no worries about overdischarge, and it fits easily in a C Mag. You may need a shortened tailspring; I'm using a special shortened and widened tailspring that lets me run 2x18650 (down through the spring, into a copper-braid-over-foam contact in the bottom of the tailcap) or 2x25500, with the 2x18650 obviously being intermittent duty only.

I have this setup, and have run over 10 hours with only one burnt bulb. No soft-start, but also no real resistance fixes. I started with a stock switch and cammed reflector, but eventually (as a result of an hour continuous burn) the focusing spring annealed and collapsed, and the switch was somewhat melted; when I replaced the switch, I used a steel braid from cheap TV cable to bypass the spring, in fears that the usual copper bypass would blow bulbs.


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## GarageBoy (Jan 28, 2010)

I want the extra brightness of the 5761, but I like the 2C form factor
Will the 18650-26 light up the bulb, or will it blow?


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## mvyrmnd (Jan 28, 2010)

I just acquired a 2C Mag with a 5761. I've been running it on 2 unprotected 2600mAh Samsung 18650's with no 

As mentioned before, you'll need to make space in the tailcap, and there are a few options for that.

It has a Kiu socket, and no resistance mods.


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## mudman cj (Jan 28, 2010)

GarageBoy said:


> I want the extra brightness of the 5761, but I like the 2C form factor
> Will the 18650-26 light up the bulb, or will it blow?



I haven't tried with AW's newer cells, but would be willing to bet that the 5761 would trip the protection circuit, hence the use of unprotected 18650s for the 5761. That is of course a riskier approach and pushes the cells to their absolute limit.


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## mvyrmnd (Jan 31, 2010)

mvyrmnd said:


> I just acquired a 2C Mag with a 5761. I've been running it on 2 unprotected 2600mAh Samsung 18650's with no
> 
> As mentioned before, you'll need to make space in the tailcap, and there are a few options for that.
> 
> It has a Kiu socket, and no resistance mods.



Just a little follow-up: I killed my bulb.

Turns out a full charge of the batteries was too much to take...


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## GarageBoy (Feb 7, 2010)

Ya know what, I'm beginning to think it'll be a cheaper build with NiMh power, albeit, slightly bigger. 
No NTC needed with 6AA, right?


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## 1pt21 (Feb 7, 2010)

GarageBoy said:


> Ya know what, I'm beginning to think it'll be a cheaper build with NiMh power, albeit, slightly bigger.
> No NTC needed with 6AA, right?



My setup:

mag 2d
kiu bi-pin setup
6aa to 2d adapter
6xaa duraloops
smooth reflector 
frosted 5761

One of my brightest lights, MASSIVE hotspot. I love it. Haven't flashed a bulb yet.

Relatively cheap/easy to set up for all it has to offer.


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## divechief (Feb 7, 2010)

I've written about my light in other thread, just a quick note here.

I am running a slightly bored 2C 5761 with AW's IMR 26500 and a AW soft start switch. I love the light. If I take fully charged batteries fresh off the charger and click it on high 

I usually try to pull my batteries off the charger at about 4 volts or so, alternatively If I run the light for even a few minutes on low it is not an issue. Tail cap current readings indicate the light will run about 20 minutes on high, around an hour on low.

And I just saw these bulbs available on E-bay for something like $3.50/bulb on E-bay if you buy a 10 pack. might just have to do that.

Dave


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## GarageBoy (Feb 7, 2010)

I already have a load of AA Eneloops and a charger
$40 for the battery holder
$14 for FM's socket
$20 for a [email protected]
$6 for glass
$40 for reflector

and voila?


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## 1pt21 (Feb 7, 2010)

GarageBoy said:


> I already have a load of AA Eneloops and a charger
> $40 for the battery holder
> $14 for FM's socket
> $20 for a [email protected]
> ...



In theory, yes. But I will say that she throws a load of heat, so I'm not 100% on how the stock switch components will hold up with the bi-pin adapter. Maybe someone with hands on experience can chime in on that one??

With the kiu socket it's pretty much heat sinked to the body (at least to the aluminum slug) so I don't worry at all about extended runtimes. 

Just a thought I had.


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