Another NexGen Question (sorry wayne)

[kakster]

I see in the specs that the max Vout is listed at 6v. Does this mean its a bad idea to use one with a LuxV?

I was hoping to use one with an S bin LuxV, which is 5.91 - 6.39v. It would be running off 2x CR123.

 

[Darell]

I'll answer. Yes. Bad idea to use a LuxV.

 

[kakster]

Thanks Darell. Guess i'll stick with the older BB for this project.

 

[Darell]

'Welcome.

With current offerings, the BB is your answer for sure.

 

[Kiessling]

IIRC the BadBoy is a pretty decent driver on 2x123 / LuxV even nowadays since the battery voltage is so close to the Vin of the LED that it hasn't much work to do .... much like the differences between the NexGen and the BadBoy beginning to show drastically only in the high outputs ...
Of course, I might be totally wrong /ubbthreads/images/graemlins/crackup.gif ... but it feels good to say something /ubbthreads/images/graemlins/tongue.gif

bernhard

 

[Billson]

Just curious, is it actually bad for the lux V or just not driving it at spec? If it puts out a max of 6V, then it should be underdriving it, shouldn't it so there shouldn't be any risk blowing it.

 

[dat2zip]

Billson,

A constant current driver will attempt to drive the voltage up till the current meets the regulated value. In the case of a LuxV a Badboy or Nexgen would not underdrive the LuxV, it will basically self destruct in an attempt to drive the voltage beyond 6V to achieve regulation.

Wayne

 

[Kiessling]

Wow ... it sacrifices itself for the "cause" ... how heroic /ubbthreads/images/graemlins/blush.gif
[stupid mode off]
bk

 

[Doug S]

[ QUOTE ]
kakster said:
I see in the specs that the max Vout is listed at 6v. Does this mean its a bad idea to use one with a LuxV?

I was hoping to use one with an S bin LuxV, which is 5.91 - 6.39v. It would be running off 2x CR123.

[/ QUOTE ]
Never mind that Wayne designed and built this converter. I say don't let these pansies dissuade you from giving it a try. /ubbthreads/images/graemlins/grin.gif The IC on the board is rated to 7V max. The ceramic caps are likely 6.3V rated parts but ceramic caps are very robust w.r.t. overvoltage generally handling 2X rated without problem. The only part on there that is likely a 6V part is that little op-amp used to implement the CC control. Folks around here think nothing about driving a Lux I at 2X rated current and beyond. Why worry about a couple of tenths of a volt over spec on that op-amp. Once the drop in LED Vf due heating is taken into account, there is a good chance your S bin will be running under 6V anyway at any reasonable drive current.

 

[PhotonFanatic]

Doug,

Easier to say when it isn't your light. /ubbthreads/images/graemlins/grin.gif

But we know you know what you're talking about, right?

 

[Darell]

You *could* choose Doug's route - and I hear he's paying for replacements when needed! /ubbthreads/images/graemlins/smile.gif

Or... you could do it right, which is just as easy - Use a Badboy. I don't really see the problem here! In a 6V, Lux5 situation, there just isn't anything better to use.

 

[Doug S]

[ QUOTE ]
oeo2oo said:
Doug,

Easier to say when it isn't your light. /ubbthreads/images/graemlins/grin.gif


[/ QUOTE ]

Much easier /ubbthreads/images/graemlins/grin.gif

[ QUOTE ]
oeo2oo said:
But we know you know what you're talking about, right?

[/ QUOTE ]

No comment on misconceptions that you may, or may not, have. /ubbthreads/images/graemlins/wink.gif

 

[McGizmo]

Has CPF's very own truth and correction cop gone renegade?!?!?!? /ubbthreads/images/graemlins/icon15.gif Oh the humanity of it all!! /ubbthreads/images/graemlins/nana.gif

 

[kenny]

OK,
So I got a lux 5 -- what do I drive it with? Also, since the 5's may have longevity 'issues', can under driving them a bit extend the life?

 

[Flatscan]

BadBoy on 1 or 2x123, DownBoy for 3 or more, in general (specifics depend on your Vf, but it's unlikely that it's much less than 6V or greater than 9V).

Heat is the bane of Luxes, so underdriving and good heatsinking can extend their useful life.