mag 3d luxeon mod ?'s

Hi, I'm new to modding and have an old Mag 3d I plan to use for experimentation. This is a bit rambling, but I'd appreciate any input. I'm trying to keep things really simple for my first mod, just doing a direct drive and a ucl lens.

Initial plan:
mag 3d body modified per Light Refineries directions
hotlips+tv1j combo
ucl lens

After looking at Modamag's direct drive post, it looks like I'd be seriously overdriving w/ alkalines and slightly overdriving w/ nimh's. Can I get away w/ direct drive using either alkalines or nimh's? Slightly shortened led life is fine, but 1/10 life would probably be unacceptable.

If I can't go with direct drive, what are my options? Doesn't a resistor essentially tie me to one ideal input voltage (either nimh or alkaline, but not both)? Would using something like the wiz2 allow me to vary battery types and still produce a consistent output?

Thanks,
baker

Baker, Welcome aboard!
"Why don't you stay a while"

You basically answered all your questions already

With 3x D Alkaline | NiMh you're gonna overdrive it for the first ~45 min or so.
Resistor will not allow you to tune in for both Alkaline and NiMH.
If you want regulation, you can use dat2zip's Wiz2 or georges80's bbFlex.

Use a resistor for the NiMH batteries.

The increased current of the Alklines (until the battery voltage sag) will cause an increased voltage drop thus limiting the current to SOME extent.

Also the higher internal resistance of the alklines will help some.

wwglen.

For me, the complexity/cost of a converter isn't appealing for a first mod...

So, could I size the resistor for 1A using nimh's and get away w/ a slight overdrive when using alkalines?

Given estimated values of:
vf_lux = 3.4
I = 1A
R_lux = 2.92
it looks like I'd need ~ .48 Ohm resistor. Does this look right? What wattage? .5W?

Thanks,
baker

Hi there, I have done may magmods like the one you want to do. :wave:
Find a good 2 watt .47 - .50 ohm resistor.
Use a good 2 part epoxy well mixed to stick it right in the back of the hotlips assembly.
Find some good 24, or 26 guage wire in 2 colors ( black and red for example.)
Then wire it up from there with a decent 15-30 watt soldering iron with pointy tip and electronics grade solder.
Wire the resistor on the (-) side so that if there is ever a short accross it for any dumb reason, nothing real bad will happen.

3rd_shift said:

Find a good 2 watt .47 - .50 ohm resistor.

Click to expand...

I got the resistor. I'll go w/ this plan...

3rd_shift said:

Use a good 2 part epoxy well mixed to stick it right in the back of the hotlips assembly.

Click to expand...

Is this for heat management purposes? I didn't see anything about this step on the Light Refineries page.

Thanks,
baker

Partly to keep the resistor from getting too hot and to make sure it stays put.

bbaker22, you'll enjoy this mod! GOod luck

Not to ask a stupid question, but why couldn't you just use a TV1L instead? I've built three TV1Ls and used each for at least three to five battery changes before selling them. Maybe the experts can chime in, but I feel comfortable running a TV1L direct on alkalines.

That TV1L won't stay an "L" Vf bin for long, especially running at high current. Expect the Vf of an L bin to drop to a mid to low K bin after a few battery changes.

I've tested L bin L3s, and both dropped by 0.3-0.4V at 1A.

So direct driving your L Vf Lux III might work now and give you 1-1.2A, in a little while, it'll be slamming the LED with something like 2A of current, severely shortening its life - it's very possible it could "instaflash" on you someday when you put fresh batteries in.

I suggest at least 0.5 ohms of resistance. Or use a regulator of some kind. Personally, I use low-dropout linear regulators that I build myself. They regulate the current until the input voltage= LED Vf, then basically go into direct drive at that point - so you get flat output for a while like is expected from a regulator, but then you get long diminishing output after it drops out of regulation (unlike the preception that most people have of regulators: that they drop off rapidly without giving you warning of low batteries)

I believe Artica Alumina better known as "AA" is the epoxy that needs to be used to attach the resistor inside the heatsink.. This epoxy gives thermal transfer by design...

This is also the epoxy used to attach the Emitter to the Hotlips...

You are gonna love it!!!


skillet

cratz2 said:

Not to ask a stupid question, but why couldn't you just use a TV1L instead? I've built three TV1Ls and used each for at least three to five battery changes before selling them. Maybe the experts can chime in, but I feel comfortable running a TV1L direct on alkalines.

Click to expand...

Good question! On the advice of at least two of the gurus here, that's what I put in my 3D mod. Alkalines, DD, and the TV1L on a Hotlips is bright, great color, and THROW! Ohhhh, yes! I have yet to exhaust my first set of batteries with it. BTW, PhotonFanatic is a good guy to buy emitters or other components from. (shameless endorsement) Whatever is chosen, enjoy building and using your throwbeast.

cratz2 said:

Not to ask a stupid question, but why couldn't you just use a TV1L instead? I've built three TV1Ls and used each for at least three to five battery changes before selling them. Maybe the experts can chime in, but I feel comfortable running a TV1L direct on alkalines.

Click to expand...

In hindsight, that would have been a better choice, but I have already purchased the hotlips+tv1j combo from the sandwich shoppe.

baker

In hindsight, that would have been a better choice, but I have already purchased the hotlips+tv1j combo from the sandwich shoppe.

Click to expand...

Ahhh... that answers that question.

Well, I personally wouldn't feel comfortable running a J direct drive at all on large C or D cells... maybe on 3AAAs, but not D cells.

I have one light that has a UX1L that runs on a Wiz2 at 937 ma and I tell you, it is plenty bright. Of course, it's a higher bin, but it's absolutely brighter than a direct drive TV1L. The regulation is nice, but there's no moon mode. It just starts flashing so you better have a backup.

I've never built a light with a simple resistor though.

Cratz is right. Using a board is very simple yet stunningly effective. I have a TWOH running on a MadMax WO that is a lot brighter than direct drive. And like people before me said, the Vf of the LED really drops. I have a 3D I built a while back that uses a TV1L emitter and afer 1 set of battery it's on the way out, very sad. It was bright while it lasted by 3 Alkalines are just too much for it now.

ick

evan9162 said:

I use low-dropout linear regulators that I build myself. They regulate the current until the input voltage= LED Vf, then basically go into direct drive at that point - so you get flat output for a while like is expected from a regulator, but then you get long diminishing output after it drops out of regulation (unlike the preception that most people have of regulators: that they drop off rapidly without giving you warning of low batteries)

Click to expand...

Hey Evan9162,

What LDO do you use??

It's based on the LM334 - Here's the thread that describes it:

http://candlepowerforums.com/vb/showthread.php?t=75204

270winchester said:

Cratz is right. Using a board is very simple yet stunningly effective. I have a TWOH running on a MadMax WO that is a lot brighter than direct drive. And like people before me said, the Vf of the LED really drops. I have a 3D I built a while back that uses a TV1L emitter and afer 1 set of battery it's on the way out, very sad. It was bright while it lasted by 3 Alkalines are just too much for it now.

ick

Click to expand...

Nick, some of us have had ***K and even ***J bin emitters last better than that.
Something went wrong with your light's assembly.
One really has to watch and make sure the emitter is in fact all the way into the heatsink before thermal glueing it in there.
What adhesive did you use?

Guys, while I don't dispute the findings of voltage shift over time, I have built many dozens of Osink magmods with ***L bin emitters and have never had any fail.
Not on alkalines, or dozens of recharges on nimhs.
Remember, I work as a security guard and took these lights with me to work
I put a LOT of use on my Osink magmods with nimh batteries at 800-1100 ma.

Like 3rd shift, I've never had problems. I made three mag 3Ds run direct drive with the shortest fattest wires I could fit through the holes in the heatsink. I used Tv1Ks and the two part AA epoxy. I've used alkalines exclusively, and given two away as gifts (I hope those don't fail). I really like those lights. I was conservative and underdrove leds when I first started playing with them. I've never used a regulator, but it sounds cool too (but more money).

The first 3D TV1K light I made, I was also scared about two much current---so I took a piece of plastic from a milk jug, cut a circle to the diameter of the D size battery. This served as an insulator between the battery's negative end and the spring below it. Then I poked a hole in it and had one lead from a 1 ohm resistor sticking up to touch the battery's negative end. The other lead was wrapped around the spring in the tailcap of the mag. This let me see how bright different levels of resistance let the light run at, but I could still take it out in less than a minute if I wanted to. I would keep the resistor in for the first couple hours while the batteries were new, and then let it run direct drive when the batteries discharged a little.

This is very unprofessional-looking when you open it up (like all my mods), but it worked. For the price of a few different resistors and a few minutes cutting up a milk jug, you could try it. Whatever you chose, its going to be a cool light. There is a reason so many people here have done it, and some people like 3rd shift have done it dozens of time. Let us know how it goes.

Thanks for the advice everyone. I have either acquired or ordered everything for my first attempt. Once I complete the mod and have some hours put on the light, I'll report back.

mag 3d w/ alkalines
.47ohm / 2w resistor
ucl lens
hotlips+tv1j

This thread, as well as others, has given me ideas for my main goal, which is a multi led bike like (ala Elektrolumens quadstar). Actually, the more I look at efficiencies, brightness, difficulty of build, etc, the more I think I should stick w/ my Trail Tech HID for my bike light. But, that's another thread...

baker