Lux III Mag mod questions

I have modified a 4D Mag with an O-sink,2.2 ohm resistor and a TV1L emitter.

1. Do I need to fasten the resistor to something inside the light?
I used a 2.2 ohm, 5w metal film resistor. It is the square white type. I wrapped the connections and then the entire thing in silicone tape. I'm not worried about it shorting out but could the soldered connections loosen from being jostled about? If it should be fastened, how do you do this and where? FWIW the light is pulling 840 mA on 4 new Duracell batteries.

2. Can I use 2 2 watt resistors in parallel?
The electronics store near me doesn't have too many of the low ohm 5 watt resistors and I didn't see any 3 watt. They have a pretty good selection of 2 watt round ones. Can I solder 2 of these in parallel to get over the 3 watts minimum recommended for this setup? I'm pretty sure I'd just use double the wanted resistance to get the value I want but am I correct in assuming this would handle 4 watts?

3. Does Arctic Alumina ( not the epoxy ) hold the O-sink in place once it sets?
When I take the head off this light the O-sink rises up about 2mm. It looks like the reflector is the only thing holding it down. Should I put the AA (non E)on the O-sink and then MacGyver something to hold it in place until it sets?

4. What resistor value should be used in a 3D to allow using NiMH or alkaline batteries with either a TW0K or TV1L?
I think I read that NiMH need a little more resistance. I have on hand .9, 1.0 and 1.2 ohm resistors.

Itwould be a good idea to secure the resistor,hot glue would work well.If the resistor is free to move sooner or later metal fatigue will be a problem.A good source of resistors in all sizes is MCM Electronics,they have a website.Or just PM me with what you need and I'll send you one N/C,since I have a pretty good selection in my shop

Hey PJ...

Answer to Q3
Artica Alumina does not set up, it stays tacky.. I used a small piece of mylar in between the Osink and light barrel to "secure" my mods from slipping out.

Skillet

Answers to your questions..
1.You could use 2 ton devcon epoxy and encapsulate it in that under the o-sink.
2.Yes. If you run these in parallel it will decrease the resistance by half, if you run in series it increases the resistance. I have ran the 4D mag with no resistor, but I am willing to gamble on my emitters. /ubbthreads/images/graemlins/grin.gif
3.The o-sink should not rise up and down. And yes you should use the epoxy Artic Silver(at Fry's or the shoppe)to mount the emitter.

[ QUOTE ]
PJ said:
I have modified a 4D Mag with an O-sink,2.2 ohm resistor and a TV1L emitter.

1. Do I need to fasten the resistor to something inside the light?
I used a 2.2 ohm, 5w metal film resistor. It is the square white type. I wrapped the connections and then the entire thing in silicone tape. I'm not worried about it shorting out but could the soldered connections loosen from being jostled about? If it should be fastened, how do you do this and where? FWIW the light is pulling 840 mA on 4 new Duracell batteries.

[/ QUOTE ]

3rd shift's answer:
Switch to a 1.5 ohm 5 watt resistor.
Set it into the back of the Osink without blocking the wire holes with epoxy.
Slide heatshrink tubes over the leads to keep them from shorting to the osink.

[ QUOTE ]

2. Can I use 2 2 watt resistors in parallel?
The electronics store near me doesn't have too many of the low ohm 5 watt resistors and I didn't see any 3 watt. They have a pretty good selection of 2 watt round ones. Can I solder 2 of these in parallel to get over the 3 watts minimum recommended for this setup? I'm pretty sure I'd just use double the wanted resistance to get the value I want but am I correct in assuming this would handle 4 watts?

[/ QUOTE ]

3rd shift's answer:
You sure can use parallel 2 watt 3-3.3 ohm resistors for 4 watts of power handling on the resistors part.
Again epoxy, or arctic alumina those to the back of the Osink.
[ QUOTE ]

3. Does Arctic Alumina ( not the epoxy ) hold the O-sink in place once it sets?
When I take the head off this light the O-sink rises up about 2mm. It looks like the reflector is the only thing holding it down. Should I put the AA (non E)on the O-sink and then MacGyver something to hold it in place until it sets?

[/ QUOTE ]

3rd shift's answer:
Whenever you get one doing that, just scratch the sides of the osink, apply thermal grease, then twist the osink a quarter turn as you put it down into the barrel.

Good luck. /ubbthreads/images/graemlins/smile.gif

Thanks for the info. I do have the emitter AA epoxied to the O-sink. I didn't want to epoxy it in to the light until I found out about the resistor.
The 4D doesn't seem much worse handling than a 3D mag and I can rest it on my shoulder when using it. Now I wish I grabbed a few more while HD still had them for $ 16.00. That and it solves the odd-battery out problem.

New question.
I just finished a 3D with a TV1K, no resistor, 22 gauge wire. With new batts. it is pulling 1.3A. Will this kill the Lux III or can it handle it until the batts. drop down? I have it Arctic Alumina epoxied to an O-sink. With used batts. it is pulling 950 mA.

It will take it. I have had one built like this for awhile. /ubbthreads/images/graemlins/grin.gif

It will take it for a while. Then the Vf will drop, and it'll draw more current. You run the risk of killing the Lux pretty quickly.

I built a similar light,suggest you try Ni-Mh cells.Mine runs about 860ma with freshly recharged cells,no problems with heating.

Some more questions.

1. 3rd_shift, when you say scratch the sides of the O-sink what do you use? I assume it is to raise the surface of it to give a kind of press fit to keep the O-sink in place.

2. Could I use Loc-tite to keep it in place? I know they make some kinds that aren't permanent.

3. How important is having thermal compound between the O-sink and the body of the light? I ran the 4D with 2.2 ohm resistor for about 15 minutes and it didn't get hot. It was warm but I could touch it with no chance of getting burned.

Sorry about all the questions. I plan on making a few more of these lights as gifts and want to make sure they don't crap out after a few hours use.

/ubbthreads/images/graemlins/bumpit.gif

I totally forgot to do the thermal grease on my 1st mod. No way it's coming back out. (NOT gonna wreck 2 hrs of soldering done with a broken tip)

Oh,
I used a screwdriver to scratch the sides to make it press fittable.
Locktite could work, but may not be needed.
2.2 ohm resistor, hmmm....
reduce it to a 1.8 and use some thermal compound grease and that should just about do it. /ubbthreads/images/graemlins/smile.gif

What resistor value should be used in a 3D to allow using NiMH and alkaline batteries with either a:

1. TW0K

2. TV1L

I think I read that NiMH need a little more resistance. I have available .9, 1.0 and 1.2 ohm resistors.

What current level do you want?
Assuming 1000mA then here are the resistor value you're looking for.

1a. TW0K with 3xD NiMh -> no resistor needed
1b. TW0K with 3xD Alkaline -> 0.69 Ohms
2a. TV1L with 3xD NiMh -> no resistor needed
2b. TV1L with 3xD Alkaline -> 0.02 Ohms (no resistor needed)

To calculate this for yourself use the following equation
<font color="blue">Resistor Required = ( Vf_lux / I_desired ) – R_lux</font>
Vf_lux and R_lux are available in the Direct Drive Data Sheet.

IMHO, you don't need any resistor for the Luxeon specified /ubbthreads/images/graemlins/grin.gif
Happy Modding!

OK, thanks. As soon as we get another color printer in here I'll have to print that chart out. I may put the 1.0 ohm in the K bin just to be safe.

I put a .47 ohm resistor in the 3D TV1K and it is pulling almost exactly 1 amp. This seems like a reasonable setup for an alkaline battery light. Thanks all.