what current is your modded Arc?

[louie]

Robo, the size and value of resistor here is somewhat rare. Panasonic sells that size as a type 0805 SMD resistor, I think. The Shoppe has the 0603 SMD resistors which are functionally the same (same wattage) but are even smaller physically. If it's not convenient to bulk up an order from the Shoppe or Digikey, I ordered several sizes from DigiKey and I'd be glad to mail you a 0.15 ohm 0805 SMD if you PM me with your postal address. Then you add that to the empty pad next to the existing 0.15 ohm and you double the drive current. I haven't done it yet myself, but I was doing some KL1s and just bought resistors for both projects.

 

[Robocop]

Thanks for the offer Louie...I hate to have you go to the trouble for a simple resistor and I will try a few local places here.We have an electronics guy at our radio shop at work and I think he may be able to help me out.
If I cant locate anything I will surely let you know and thanks again.
Just out of curiosity what would happen if I removed the single resistor that is on the board now.If I remove it and solder across the connection would it be direct drive?...would it even work this way with no resistor?

 

[cgpeanut]

DaveT ,

The silver arc is polished bare aluminmum, I used a dremel polishing tip and coda aluminum paste to polish it up. Coda is used in aluminum bike frames and works perfectly IMHO here's more pics for you to drool /ubbthreads/images/graemlins/grin.gif

Robocop,

It would be diffucult to salvage smd resistors from old circuit boards, even if you have the right size you may not have the right value. You might end up frying the lt1618 chip and/or other components then it would be more difficult and expensive to fix. Just bite the bullet and order some from the sammich shoppe. or take the offer LitFuse and others are giving you. Believe me once you get into modding lights there is no turning back /ubbthreads/images/graemlins/smile.gif you would need these parts to mod other ligths.

The sammich shoppe also sells mineral glass lens I have not tried this but the 17mm should fit the arc-ls ask Wayne.

 

[Hallis]

Thats a lot of valuable lights right there

 

[louie]

Robo, I don't know the circuit, but I would not recommend removing the sense resistors or using wire myself!

 

[Hallis]

It's smaller stuff than id want to screw with for sure.

 

[CalgaryGuy]

Robo, if you want to short circuit the .15 ohm, you can just solder a wire on the spare pad beside the .15 ohm. But be aware that you might fry something else if you do that!

While you have your LS opened up, make a reflector from tin foil paper (the stuff you use in the kitchen). It'll give you an extra lumen.

 

[stefx]

[ QUOTE ]
jtice said:
To make a stock Arc LS board do 667mA, you ADD ONE 0.15 Ohm resistor.


[/ QUOTE ]

right.

[ QUOTE ]
jtice said:
To make it 500, you ADD ONE 0.1 Ohm Resistor.


[/ QUOTE ]

Shouldn't that read 'you ADD ONE 0.33 Ohm resistor'?

Stef(an).

 

[Robocop]

This has been a great thread as I have learned much from it.I am not going to short or remove the resistor however I was just curious what it would do if this board had no resistor.Would it then be classified as a wide open board?
I have one option left with finding these resistors locally and if nothing else I will order some along with some reflectors and other emitters I am wanting.I am even thinking of trying out some colored luxeons as I have never had any colored lights other than 5 mm LEDs.
The Q3J actually does pretty well with the factory setting on this board.I am happy with it as is however the curiousity has got the better of me just to see if I can solder another resistor and actually make it work...man this thing is small.
Great thread and I really appreciate all the help.And also to cgpeanut that is an incredible collection of lights you have there...very good taste I must say.Now that I can remove the internals at will I may also try my hand at polishing once I get this other tech stuff handled.

 

[LitFuse]

[ QUOTE ]
Robocop said:
I am happy with it as is however the curiousity has got the better of me just to see if I can solder another resistor and actually make it work...man this thing is small.


[/ QUOTE ]

Wait till you see the size of the resistor from the Shoppe, it's about 50% smaller than the stock one. Don't drop it whatever you do, it will never be seen again. /ubbthreads/images/graemlins/help.gif

The colored LEDs are fun to play with, but not very practical. I did a bunch of them, but I sold them all. Royal Blue was my favorite, and I never could find a nice cyan, all I got were "greenies".

Peter

 

[Robocop]

I am out of options now and will simply have to order a few of these with my next on line order.If they are indeed smaller than the standard SMD I see on this board then I am surely out of my league here.I cant solder that small...at least not with the 15 dollar soldering kit I have..hehe
I am still curious about the question I asked earlier.Not that I am going to do it but what would happen if I removed the resistor on this board???.....what current would it then be pushing or would it even work at all?

 

[CalgaryGuy]

If you remove resistor on both pad, it'll have a very big resistance which mean the light won't work at all. If you short it with a wire, the light will be very bright but will probably run for 5 minutes and something will fry.

Robo, you should be able to solder it with out any problem. I have tried with my Arc LS with a 10 ohm surface mount resistor without any problem. My solder is a $15 one as well.

Anyone care to split a bag of 0.15 ohm 0805 SMD or sell me some?

 

[Robocop]

Ok thanks for the information however I am still curious...What determines the mA of this board if there were no resistor?...would it be the actual capacity of the battery or the VF of the Luxeon or the limits of the board....I am trying to work this out in my head here.I know there are 2 pads for a resistor with only one used at this time.What would my mA be if I shorted the spare pad and left the factory .15 resistor as is?..also any guess on what the mA would be if I removed the single SMD resistor and soldered that location.
Why do you say it would be bright for about 5 minutes then stop working?...Would it simply overstress the other components of this board if the resistor was removed?....I am not trying to keep asking however no one has actually answered directly and said what will this board do with no resistor?..I remember removing the resistor on other boards(Dorcy AAA and AA)with no ill effects however that is a different board I know....I am not going to remove this SMD and I actually plan on leaving it alone for now however I am just dying to know what will the specs be on this board with no resistor and a single cell.

 

[CalgaryGuy]

I don’t have the schematic of the circuitry but from what I’ve learned when I took electronic engineering, this surface mount resistor plays a very big role in controlling the current on the Arc LS. For the 5 minutes, it’s just an estimate. It could be a low as 2 sec or as long as 10 minutes. For 2 sec, it would be when current goes though it so quickly that some other component can’t handle that much current and will break down. For 10 minutes, it has to do with heat being a factor. LS are not design to dissipate heat fast enough and it will build up to a point that it’s too hot for some component and that component will give up. There are scenarios in between as well so my guest is 5 minutes of run time if shorted.

Yes, some other circuitry doesn’t care too much if one of its resistor is removed depending what the resistor do. For example, if a resistor is part of the circuitry that controls the regulation, removing that resistor will make the light run unregulated, but to the eye, we can barely see a difference.

If you remove the .15 ohm resistor, my guest is that the light won’t turn on at all. This resistor seems to play a very big role. For me to be certain, I’ll need to take a look at the schematic.

 

[ZuluWhiskeyFox]

I soldered a .22 ohm onto the spare pads. Supposedly this will give me 560ma to the led. Got them from the Shoppe. At this setting it is brighter than my 4+ on #1. As for my soldering iron. Well it's a cheapy. I simply ground the tip to a long, slender, pointy tip. Work quite well.