Red KL4?

Any chance Surefire will make a red KL4? I don't even know if the 5 watt Luxeon Star is made in colors. I have the KL1 and KL3 in red. Thinking of getting the L1 in red also. Why doesn't Surefire advertise the fact they make the KL1 and KL3 in red, blue and green?

There is no red 5-watt luxeon (yet). The KL4 appears to be boost-only, so it would direct drive a red 1-watt emitter, even on 1x123. Since red is often used as a night-vision preservation light, do you really need it in a 5-watt level of brightness?

Cool factor maybe?
Otherwise, like Brad-a-like said, a 5W HD with a bright spot will still toast your eyeballs.

For maintaining night-vision, I use my Arc AAA red. I think a 1 watt is just about all you really need...unless you're planning on doing a huge flood lamp with the 5W
/ubbthreads/images/graemlins/drool.gif


-Jason

you could always buy the red beam filter.

Brad-a-like? ROTFLMAO. tylerdurden, I guess you can take that as a compliment. At least you know he's not calling you ugly /ubbthreads/images/graemlins/grin.gif

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tylerdurden said:
'The KL4 appears to be boost-only, so it would direct drive a red 1-watt emitter, even on 1x123.'

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Could you explain that to an old fart with no electrical knowledge? /ubbthreads/images/graemlins/grin.gif Did you mean to type "red 5-watt emitter"? I have a red Inova X5T, and that only uses one battery. Always wondered why? Laymen's terms only, please.
oldgrandpajack

[ QUOTE ]
oldgrandpajack said:
Could you explain that to an old fart with no electrical knowledge? /ubbthreads/images/graemlins/grin.gif Did you mean to type "red 5-watt emitter"? I have a red Inova X5T, and that only uses one battery. Always wondered why? Laymen's terms only, please.
oldgrandpajack

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I'll try. Someone will correct me if I munge this. Luxeons have a "Vf" rating, which is the amount of voltage required to drive them at spec, which is around 350ma for 1-watt and around 700ma for 5-watt IIRC. If you supply more voltage the emitter will draw more current, and if you supply less voltage it will draw less current. A boost or buck circuit works by changing the voltage until the specified number of milliamps is being drawn.

Most white 5-watt Luxeons have a Vf in the 7 volt range, higher than the 6 volts supplied by two 123A cells. The circuit in the KL4 is (I think) "boost only," which means it can raise the voltage coming from the batteries to that required by the emitter, but not lower it. If the input voltage is below the Vf, the boost circuit will raise it to the Vf, but there is a cost, as this circuit is not 100% efficient, so some battery power is wasted before reaching the LED. If the input voltage is higher than the Vf of the LED, the circuit goes into direct drive mode, where it effectively does nothing. The full voltage is passed to the LED, and if it is too much higher than the spec Vf, it will fry the emitter.

White 1-Watt emitters generally have a Vf around 3.5 The circuit in the KL1 is a "boost/buck" circuit, as it is designed to work with the 3V E1 (in boost mode) and the 6V E2 (in buck mode). Buck circuits are generally more efficient than boost circuits, but are still not 100% efficient.

Red 1-watt emitters generally have a Vf below 3v, so a red KL1 is in buck mode even on a E1. If a boost-only circuit were used, it would be in direct drive mode.

Better? /ubbthreads/images/graemlins/smile.gif

Good effort. Why do red emitters require less voltage than white? Does that mean that red LED's have a longer run time? Are they brighter than other colors if everything else is equal?
oldgrandpajack

Ugh... I was typing up a response and my PC bluescreened.

Anyway... LEDs use different elements to create different colors. Whatever chemistry the red emitters use must require less power than the white emitters. I don't know about relative brightness.

Given a red and a white luxeon with identical regulation circuits and power supplies, the red emitter will have a longer runtime. Actually, given any two luxeons with identical power and regulation, the one with the lower Vf will have the longer runtime, assuming both are driven to spec.