Most photons?

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
I'm curious,
A Q3 overdriven at 500mA or a V3 (5W) underdriven at 500mA? The latter would be(?) equiv of 4 1Ws driven at 250mA. How does it look from the efficiency side- would the same light run cooler. You guys been playing with these things far longer than I have /ubbthreads/images/graemlins/grin.gif .

Larry
 

paulr

Flashaholic
Joined
Mar 29, 2003
Messages
10,832
Um? A 5W underdriven at 500 mA is using 2x as much power as the overdriven 1W, because of the 5W's higher voltage. Is that really what you wanted to ask?
 

Christoph

Flashlight Enthusiast
Joined
Aug 18, 2002
Messages
1,680
Location
Hagerstown,Md
Larry I'm getting ready to try the same thing that question is right on time for me. I will be using 6 1/3AA 300mah nimh's (or I may go direct drive with them,need to study it some) Which config would result in more light? which in more heat? @500ma /ubbthreads/images/graemlins/smile.gif
Chris
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
paulr,

You caught me! (I am prone to get a little goofy by bedtime on saturday nights /ubbthreads/images/graemlins/grin.gif .) Where I really wanted to go is emitter efficiency, and should have said 5W driven at 250mA. With 4 times the emitter area, how would the efficiencies and total luminosity compare? I will try and spend some time at Lumileds' site at work tomorrow, but was hoping some of you guys been there/done that. /ubbthreads/images/graemlins/smile.gif

Larry
 

McGizmo

Flashaholic
Joined
May 1, 2002
Messages
17,290
Location
Maui
Larry,

V3 driven at 250 mA may have higher effacacy (sp?) but the color shift might be less than desired. I would guess more photons than the overdriven Q3. If you want to focus the photons into a tight beam and use the same Optic/ Reflector for either LED, then you know what you'll get...... If you are using a boost circuit for both then you are looking at more cells and longer run time with the V3, I reckon.

So many choices, so many options; so little time. /ubbthreads/images/graemlins/grin.gif

- Don
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
Thanks Don,

I dug out a P2 HD and U3 star, 2 micropucks, and a 123. (I love the smell of rosin in the morning. /ubbthreads/images/graemlins/grin.gif ) I made a note a while back that the 5W gets only 160mA with 3Vin on a puck. Side-by-side, with NX-05s, while the 5W color seemed Ok, well, you know what I got /ubbthreads/images/graemlins/grin.gif . (Beam so bad it was impossible to really judge luminosity.) I tried all of my cut-up optics, and the only one with an acceptable (to me) beam was a 30mm cut down to .85dia, and shortened to .340. Round hotspot with no black hole in the middle, but a square corona. I wonder if anybody has done a LD transplant on a 5W, and what would result?

Larry
 

McGizmo

Flashaholic
Joined
May 1, 2002
Messages
17,290
Location
Maui
Go Larry! Go! /ubbthreads/images/graemlins/grin.gif

Man if you're still playing at the *small* end, stick with the 1W's! 1x123+5W = Yuk ............ Prove me wrong! /ubbthreads/images/graemlins/grin.gif

- Don

BTW, if it's any consolation, I'm currently in way over my head so maybe we can have a contest to see who wastes the most time and comes up with the nicest pile of (s)crap?
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
Don, "...*small* end, stick..." In my case the more appropriate expression is *Short end of the...* /ubbthreads/images/graemlins/grin.gif I missed out on one of tonyb's AAA-size modules, so all that remains is an Ncell-micropuck-1W/NX-05, cut down to .450dia, and shortened to abt .225. I have a badly butchered optic of those dims, and it actually still makes a beam! I think tonyb and ledsmallasposible (apologies in advance for the sp)have only begun to scratch the surface of what may be possible with underdriven LSs.

Larry
 

Doug Owen

Flashlight Enthusiast
Joined
Jan 30, 2003
Messages
1,992
This should be easy enough to sort out. Let's assume light output is linear with current, therefore will scale (probably a very safe assumption in this case)..

First the Q3 at 500 mA. Using the midpoint of the bin, Q3s produce 38.2 Lumens (at 350 mA) times 500/350 is 54.6 Lumens at 500.

V3s do 130.6 at 750, derated to 250 would be a third of that, 43.5. Making the Q3 the (slight) winner.

Overall heat generated should be about the same, however it's spread over four times the die in the 5 Watt unit, so you're better off WRT lifetime and light loss from high temps. Remember, it's not really the heatsink or slug temperature that counts, but the die temperature.

FWIW, I'm a big fan of safe margins *under* specifications (in case folks haven't figured that out yet....).

Cost is another matter......

Doug Owen
 

paulr

Flashaholic
Joined
Mar 29, 2003
Messages
10,832
I don't think the output is linear either. Efficiency decreases at the max end of the operating current range. The 5W is likely to be a little more efficient.
 

Doug Owen

Flashlight Enthusiast
Joined
Jan 30, 2003
Messages
1,992
[ QUOTE ]
paulr said:
I don't think the output is linear either. Efficiency decreases at the max end of the operating current range. The 5W is likely to be a little more efficient.

[/ QUOTE ]

Don't tell me, tell Luxeon. For sure the curve for the 5 Watt clearly shows it, and the one for the 1 Watt shows no sign of change. FWIW, the one I ran up to 500 mA tracked just fine. Heat is, of course, another matter.

Check the specs...... Like I said, while I wouldn't go there, it looks to me like that's what happens.

Doug Owen
 
Top