ARC LS circuit capable to drive 5W LED

ARC LSL's are really cheap in the moment and changing optics+ LED is also easy.
I would like to change the LED to a 5W (current unchanged at 333mA) and the optics to MCFlood. This should give a nice flood with high efficiency.
I know, that the LT1618 chip is suitable for the 7V, but I don't know, if the capacitors are rated for this voltage. Does anybody know, if I have to change the output capacitor?

best regards,

Peter

PeterB,

i think that at 333mA the 5W will be dimmer than the 1W. /ubbthreads/images/graemlins/frown.gif

I think the 5W will be brighter. LED's are more efficient when they're underdriven contrary to conventional wisdom. My guess is that the output cap on the Arc is a 10V part. The next step down in voltage I think is around 6V. But again, this is my guess.

CM

I have a grey kit running a 5w, it is brighter. From the threads I've read, Wayne(the designer of the Arc Grey circuit) says it will even run higher than the 330ma I left it at no problem, just have to watch out for heat issues. I think i will boost mine to 667ma later.

Yeah, I've done a couple of boosts (just adding another .15 ohm resistor in parallel with the existing one) with no problems so far (several sets of batteries). It doubles the output current...

Have someone just shorted the R15 ?
I've read here on CPF that it can be done without great problems.

Shorting the resistor is not a good idea. The circuit will behave as if it's running open circuit (no voltage across the sense resistor) and probably toast the switch in the controller. Although a short across it is probably not zero ohms, it may be a few milliohms but still low enough to do permanent damage to the switch. I have boosted mine to an amp but it just runs wide open on a single 123 and you get very little return for all that power you're drawing from the cell. Needless to say, I took it back down to a more modest 667mA but it's still too much from a single cell. A Li-Ion will probably run it real nice.

CM

Would efficiency of the booster circuit suffer since it has to boost to twice the original voltage now?

I got a Arc 2x123 on mine when Arc sold off the bodies.

You put that 2x123 on a un-modified circuit and 5W?

[ QUOTE ]
admedeus said:
You put that 2x123 on a un-modified circuit and 5W?

[/ QUOTE ]

Yep... Works fine. never bothered to do a full run test, but it does get a little warm... /ubbthreads/images/graemlins/smile.gif

Actually, I did add an input capacitor...

I gotta try that. I've got one of those bodies and was trying to figure out what to do. Besides, a little hand warmer would be nice this time of year.

What kind of cap? Did you replace the one on the circuit or add it somewhere?

If your going to use the 2x123, make sure you have the 5w on there. I've never tried to do it with a 1w... you might release the magic smoke...

I added the cap on the input side, there was none on the original design.

Oh yeah, figured that, I've got all the magic smoke I need. I gues that shows how close I've looked at that circuit. I was curious what size cap and if you used smd or not. Have you tried with a Fraen or some other optics?

I've tried the NX05, McFlood, FraenLP, and might try the NX01 later. Because of the 5W larger die size, I see 4 spurs of blue like a star and a dim donut void in the middle with the NX05 and Fraen(less dim void). The McFlood has a nice flood beam. I'll have to look on my bench later to get you the specs of the cap(smd), It was a suggested mod from W. I might have a spare if you need it. If I remember, it was to cut the flikering when you turned it on.

If you've got an extra, I'd be glad to pay you for it.

It's ok, just make a donation to CPF. PM me when you have a chance.