Dummy reference guide to SF A2 modding with MJ led (or 35k 5mm) leds

[Arkayne]

I was wondering, do you think the SF RED LEd ring has different resistor values than the white?

 

[AuroraLite]

Arkayne,

I do have one A2 in Red as well(stock red led), but it is not with me. I should be able to check it in a day or two, and I will post my findings here soon.

Meanwhile, if anyone owns a Red A2, please jump in to contribute.

 

[leukos]

If memory serves me, my red LED ring has the same resistor values as the others, 33ohm.

 

[Arkayne]

hmmmmmm I'm reading 100.4 ohms on my red ring. Can someone clarify this?

 

[AuroraLite]

Arkayne,

Finally get to my A2 porcupine with Red leds, and I can now confirm that SF indeed do use 100 ohm resistors for the red led rings (I had taken a picture with a magnifying glass as well as measuring it).

With two pretty full 123 batteries(5.95+ v), the voltage dropped across one single resistor is 3.85v. That in turns give us 38.5 ma. So I believe each red led is driven at ~38.5ma.

Another observation is that, unlike my black A2, which all the screws(negatives) are interconnected with an outter ring of copper; each of the red led is connected to the negative via each screw individually and seperately.

That really doesn't matter much to the operation of the red leds, except when you do try to measure the voltages, then you have to make sure you connect all the negatives via each different screw holes seperately to get a correct reading.

In short, if you do intend to swap the leds into another color(for ex, MJ leds), then you might have to switch the resistor to a different values to get the full benefit/brightness of the new leds.


####################

Another confirmation with my uncut MJ leds mod (on the black A2 which has 33.3 ohm resistors), the voltage dropped across the resistors are 2.613v. And the current driven to each of the MJ leds should then be ~78.5ma(which is overdriven, but should be quite safely overdriven with no ill effects).

Hope this helps!

 

[Arkayne]

Ahh man, replacing those dinky resistors may turn out to be more work than I bargained for. I'll just keep an eye out for a spare LED ring so I can make an MJ White ring.

thanks for the help!

 

[IsaacHayes]

Arkayne: Try www.lsdiodes.com for the THC3 Red Leds. They are 100ma Reds supposed to be really bright.

 

[AuroraLite]

Arkayne,

Issac's suggestion look quite promising, so it is definitely worth looking into. Also, IIRC, wquiles had also done the same mod here, and he might have switched his resistor value(for using with rechargables?)--might want to pm him for his opinion.


Issac,

I remembered seeing those THC3 leds somewhere, and they look awfully similar to the ISP 5mm 100ma (MJ uncut). Did ever you try to compare them side by side? And what are their differences?

 

[IsaacHayes]

heh, just getting back to this thread. I believe they are the same. I have not compared them I don't have them both. But I would imagine they are the same... MJLED I belive was selected bins with low Vf so DD 3volts they would be brightest.

 

[wquiles]

Arkayne,

Issac's suggestion look quite promising, so it is definitely worth looking into. Also, IIRC, wquiles had also done the same mod here, and he might have switched his resistor value(for using with rechargables?)--might want to pm him for his opinion.

Indeed, I did replace the resistors with higher values when I swaped the OEM white LED's for 35K's from KevinL - details are shown in this post. I went from the 33ohms to 110ohms, which give me excellent results with the rechargable cells that I always use (MP700's from AW).

After months of use and at least 40 cycles through the MP700's, I still recommend using larger resistors if using rechargables in the A2

Will

 

[AuroraLite]

Thank you guys for the replies, I can't talk for long now(in a rush to go), but I do have some SMJ enrouted to me as of now...and I look forward to putting them in my A2...

The fun just never ends, and I will report back with the new results. :devil:

 

[flashlight]

Would the SMJ LEDS be better than the 40K ones?

 

[wquiles]

Would the SMJ LEDS be better than the 40K ones?

Better in what way?

Will

 

[AuroraLite]

Flashlight,

:wave:

Hmmm, good question, and I honestly can't say I know.

From what I read, the SMJ uncut is simply a 4 die 5mm led that has a 35 degree viewing angle and rated at 15 lumens(!) at 80ma.

I figured that even if it might not be driven at full 80ma(more or less), and the lumens rating might suffer--but with three of them put side by side with a reflective surface, it will still be a truck load of lumens coming out from the business end for 5mms. :rock:

 

[wquiles]

In terms of brightness, I recently swaped 35K's for the older SMJLED and the brightness went up significantly. In terms of heat (being able to run at higher current for longer times), I expect that the SMJLED will do better than the 35K (or 40K, although I don't yet have any 40K's yet).

Will

 

[AuroraLite]

Wquiles,

That was the path that I took as well--swapping out the 35k for the MJ leds, and I was happy with the result ever since. One of the major consideration/reservation I had with the 35k, IIRC, is the output after overdriving at an exteneded period of time.

The MJ I was told to be ok to be overdriven at 100ma, and my meter told me it is at around 78ma each in the A2. So the MJs are probably a more long-term viable option than the 35k.

Now only if I could put in the SMJs... :devil: And I will report back for the result.

 

[wquiles]

That was the path that I took as well--swapping out the 35k for the MJ leds

My apologies. I did swap 35K's for MJLED's, but not in my A2, but in my POP-driven G2 LED Module . My A2 still has the 35K's and the larger (110ohm) resistors so even with the rechargable batteries I am doing fairly good (40mA max) so far - later on if one of them ever dies, I will put MJLED's to replace them

EDIT: On this post I talked about my bench measurement where I found the nedd to increase resistance value when using rechargable CR123 LiIon cells. After using my A2 for a while, even at 40mA to each one of the 35K LED's, I am beguining to think that part of the reason the LED's on the A2 last so long is that the LED's are pressed into the solid metal head/reflector assembly and that this does provide for an excellent path for heat disipation. Anyone else agrees?

Will

 

[flashlight]

Thanks for all the replies guys. Now all I need to do is to get an A2 & someone to change out the LEDs for me.

 

[lasercrazy]

I just replaced the angry blue leds in my A2 last night with some SMJ leds. It has a very bright and even flood of light now.

 

[AuroraLite]

Will,
I tend to agree--I remembered using the original leds for extended period of time and having it becoming warm in hand...

Flashlight,
Good luck to your future mod, and I assure you won't regret it... :naughty:

lazercrazy,
Ahhh...man, you beat me to it! Any comparison beamshots?