Lux III TWAK at 1.6A in KL3 with PM6 reflector

OK, I've been getting the itch to do an overdrive of the Lux III's thanks to Mr Bulk. Does 1.6A sound like an overdrive? Vf is 4.1V so power is 6.56W! I'm not that impressed with the output since it puts out less lumens than an L4 which is driven at less than 5W. KL3 gets hot pretty quickly but still manageable due to the large mass and surface area. I think the point of diminishing returns on drive level is somewhere between 700mA and 1A. Do these numbers sound familiar?

I'm gonna wait till tonight and play with it in the dark. I think this is the first *regulated* overdrive at 1.6A on the Lux III's. The KL3 circuit is just humming along at these current levels. International Rectifier makes some great FETKEY's, and Linear makes nice controllers. I don't expect to keep this bias level since going back to 1A does not decrease the light output appreciably and I want reasonable runtime. I expect the 1W parts (R2K's) to perform similarly but I'm burning out on modding and need to take a break.

CM

/ubbthreads/images/graemlins/thumbsup.gif

Woo hoo! Way ta go, Chris!

Oops, now you'll have to go get a light meter (heh heh). It'll seem like you got a new lease on your mod-life, because now you get to measure everything in a new way!

Actually I think the thing about the eye's perception of brightness is relative, meaning that if a 300 lux light suddenly increases 600 lux, you'll see it with your eyes immediately because of the doubling of output. That same 300 lux increase in a light already making 900 lux will not be nearly as noticeable without an objective measuring tool. I have found that's when a light meter comes in handy. See? Everything's relative!

Glad you went with that 1.6A though. I take back everything I said via e-mail... /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif

Hmmm, light meter. It's on my long list of "must gets". Yeah, I take back everything I said too /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif /ubbthreads/images/graemlins/grin.gif.

Come on night time. I want to see if there's a difference in use.

Perhaps Mr Bulks nickname ought to be Mr. Overdrive /ubbthreads/images/graemlins/blush.gif

--Jerry

Are you kidding GrayFox? Over drive is commonly referred to as "Charlie mode"! /ubbthreads/images/graemlins/grin.gif

Actually I like "MR O.D." better - no, waitaminute...

These guys are local to me. I picked mine up for $84 +tx.

http://www.tequipment.net/WavetekLM631.html

Beretta,

Don't be posting prices like that /ubbthreads/images/graemlins/tongue.gif I'm that much closer to getting one now. I thought they were over $100. Hmmm, I need to do a few more mods to help pay for one.

CM

Yeah, I got mine on sale for $85 plus shipping, Circuit Specialists I believe it was...this CPF "Gold Standard" of light meters (or given the affordable price, make that the, uh, Tin Standard).

Here is where I bought my LM631 lux meter [same place as Charlie mentioned]:

http://www.circuitspecialists.com/prod.itml/icOid/3401

$83.95 AND they will send you a nice DMM [worth $29] as a bonus, just be sure to enter the special offer code to get the free DMM

Hey! I never got no DMM! Oh well, timing is everything I guess...

The DMM is part of a promotion they are running right now. I would have gotten mine there, but I wanted it right away and I just swung by and picked mine up.

[ QUOTE ]
CM said:
I'm not that impressed with the output since it puts out less lumens than an L4 which is driven at less than 5W.

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That's not surprising, since the L4 is effectively powering four single dies at relatively low, underdriven levels, whereas you're wildly overdriving a single die. I wouldn't be surprised if the 5-watter isn't twice as efficent on a power-to-lumens ratio. I'd bet your mod throws a LOT further, though. /ubbthreads/images/graemlins/smile.gif

tyler,

You're right. The 5W are driven at a level where you get more photons/electrons so to speak. The mod does throw impressively. It's got a very narrow beam, maybe too narrow for closeup work. I consider it a turbo head LED for the C3. I dialed it down again to 1A and prefer it at that drive levell since I don't give up much light. About two hours on two 18500 Li-Ion cells at this drive level. The TWAK's are still a great value for $12. It's equal to an R 1W in output, with much better tint. I'm gonna have to get some more.

CM

The LM631 maxes out at 20000 lux. Some LED lights are approaching this limit (measured at 1 meter), and will hopefully exceed it during 2004. Many incandescent light will exceed 20000 lux.

You can always use the footcandles scale (also maxes at 20000) and multiply by 10.76, but you might want to consider a light meter with higher maximum lux reading. I've got the LM631 and am happy with it, but would just as soon not convert.

Or you could move your light to 2 meters away from the meter, and multiply the result by 4.

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evan9162 said:
Or you could move your light to 2 meters away from the meter, and multiply the result by 4.


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Really? Is that a bonafide formula? Oops nevermind, I don't have that much space in my pitch-black laundry room.

Yes, light intensity falls off by the inverse square of the distance. You can test it out to verify it yourself. Measure at 1M, then at 2M, and compare your lux readings