The There Are No Stupid Questions Thread

Thank you for the advice, JasonWW. I asked my question in the XHP50.2 thread.

I have sense resistors in the 2512 and 1206 sizes with 1 or 2W. Maybe the leds would survive if I add a R082 sense resistor to each of them. When I measured the tailcap current with two Liitokala 26650 and four Luxeon V2 it was around 9A on Turbo.

SST20 is a small, throwy LED available at 5000K and below, and in high CRI below 5000K. To my knowledge, the 70CRI versions out-throw XPL-HI despite being domed.
SST40 is a large LED capable of very high output (over 2000 lumens at like 6+ amps). It’s not available below 5000K nor in high CRI. It’s a floody LED due to its size, but gets used in throwers due to sheer output and compromise of lumens vs. throw.

Thank you, Tom E, good idea to use 24AWG wire.

Djozz tested the XHP50.2 up to 12A and it didn’t burn out. But once I read about a build with 7 XHP50.2 and two 26650 cells in direct drive where the XHP50.2 burned out one after another. So I’m concerned because it is said that the 6V XHP50.2 has weak internal connections and individual dies become dark easily.

I think with Cree leds the Vf is lower if they are 90CRI. I just assumed it would vary with the bin as well.

Currently, I want to mod the Haikelite SC04 whose reflector happens to fit a Q8 MCPCB perfectly. I have a TA driver with LDO and four Luxeon V2 wired 2S2P which work nicely. However, I want more power and a bigger hotspot. If it goes well, I might try it also for the Q8 with a 2S2P mod.

Ohhh, interesting bout the SC04, 2 cells config I'm sure. I've done the thin long wires in other lights to reduce amps - works well, and actually some stock FET based drivers simply use long twisty traces on the driver to result in the same thing.

This was an example from a 12X SRK. I bypassed the squiggles and got more amps:

I did not hear of a single successful use of 50.2 with FET driver. They all burned out. Some lights used really weak cells and lasted a couple months, but it eventually burned out as well.

This is why no one builds that combo.

Some leds work well with FETs and some don’t. I would ask around a lot more before committing very much money into the build.

The 3v versions are a different beast. They can handle FET drivers no problem. Of course using a single 26650 will reduce run times, but it might be better to just swap a new cell in than to have the 6v leds burn out.

Hey Jason, in expanding my search for a mid-sized thrower, I was gearing myself up for the Sofirn SP70, but then reconsidered the FT03 with SST-40. Seems that dedoming it produces a reasonable bump up in throw. Not as much spill as the SP70, and not same output level (XHP70.2), but coming in at half the price it looks pretty attractive. Have you dedomed many LED’s? I’m trying to figure out the best way to do it without having to remove the star.

Trying to dedome without removing the MCPCB from the light is asking for trouble. If your cutting angle is slightly off you’ll scrape phosphor from the emitter and end up with a blue LED instead of a throwier version of what you had.

Now is a great time to learn to solder, desoldering and resoldering wires to the star is incredibly easy. Matt Smith has great videos giving soldering/reflow tutorials:

The FT03 and SP70 are very different lights even though their throw distanceis about the same. The SP70 is like 6,000 lumen with a big hot spot and can light up a football field. The FT03 SST-40 is about 1,800 lm and has a much narrower beam. One is light and pocket sized (like jacket pocket) and the other is heavier and way too big for a pocket (I actually slip it in may back pocket with slacks). So it depends on your needs. Light up a football field or spotting smaller stuff at a distance. A bit like a shotgun compared to a rifle. Big wide beam of light or narrow and precise beam of light. Each beam size has their pros and cons.

I’ve only cut a couple domes. One was an old xhp70 just to see the change in hot spot size and throw, but I didn’t like the loss of lumens. One was a xhp50.2, but I didn’t like the tint shift. I dont really bother with slicing anymore.

You do have to remove the star. It’s a delicate process with a razor blade. I think the SST-40 needs to be sliced (some led models are chemically softened and lifted off).

The star must absolutely be removed.

To do it properly, you should really reflow it onto a fresh star that has never had solder on its +/- wire connections. This will allow you to use washers of varying thickness as a guide.

If you search BLF, there are LED slice or slice and dice guides.

Post #1000!

(at the moment)

I have done some limited soldering & desoldering. Actually replaced NiMH batteries in a rechargeable shaver, and reconnected a loose wire on a speaker circuit board. But I’m not adept at doing this (need more practice). I do realize the need for a totally parallel cutting angle. My expectation is that if the cavity is shallow enough, it would be possible to do with the star still in place. I’m lazy! But if it’s challenging to get a proper cutting angle, removal definitely makes sense.

Yes, I do recognize the different form factors (FT03 closer to EDC, while SP70 is not) and the SP70 having tons more spill. I was thinking more about the effectiveness of the hotspots. Anyway, considering that I have an EA4 and a EC4GT for throwers, the FT03 is probably a bit of a duplicate (just 800 lumens more powerful). For a bit I was hung up on wanting Anduril (or NarsilM), but for a dedicated thrower, not as important. The SP70 UI actually seems decent.

Just taking the MCPCB wires on/off doesnt take much finesse at all and is some of the easiest soldering I’ve ever done honestly.

i have an LD01 that works Intermittently. the outer ring on the driver where the body makes contact when twisted seems to look scratched up. is it possible that this can wear down and prevent it working? how would one restore it? thanks.

A Fenix LD01? That driver does not have a retaining ring, right? The battery tube just screws against it?

It’s possible it can wear down the metal pcb traces (copper I think). More likely it’s just a bad contact somewhere else in the circuit.

Power goes through the threads, battery tube, tail cap, springs, etc. I would clean all those first. They can get an oxide coating that hurts the electrical flow adding resistance. If the problem really seems to be wear related on the driver traces you’d need to add a thin layer of solder on top. Some people will add a small blob of solder on 3 points and then file/sand them down so they are the same height and the battery tube presses down evenly.

Yes you’re correct, there is no retaining ring. its going to be a pain getting that driver out. i’ll try cleaning what i can first. thanks Jason.

Edit for Info: Its and older Twisty light

I’ve not yet done it. I see photos & videos where it’s very small wires in tightly confined space. Desoldering? Sure. But soldering the wires back on? I’m assuming you need tweezers & clamps carefully applied to help keep the wires in place as solder is applied. Maybe I’m just paranoid & should dive into it. Try out on cheap lights first. Anyway, I thought it was worth exploring alternatives.

You need a decently powerful iron because a lot of the mcpcbs are really good at soaking up heat plus that heat can transfer to the head. You need narrow long tweezers or some small tool that fits in there. I use a dental scraper. As you heat the soldered connections the wire might pop up or you might have move it to the side. Same for resoldering. You’ll need to hold the wire in place while you attach a blob of solder to the iron and reach in to attach it.

Once I remove the star I clean the old solder off, apply flux and put new leaded solder in it’s place. The stock solder can be unknown and might be poor quality. I put the good stuff on it. Once back in the light I use alcohol on a q tip to clean the excess flux and make it look nice.

Maybe someone can explain this to me, as I seem to be too dense to comprehend it.

Why is it that if I were to go to Amazon and buy X (coffee-grinder, bluetoof earmuffs, sock-hangers, anything), within a week I’d get inundated with emails from them that I “might be interested” in another X (coffee-grinder, bluetoof earmuffs, sock-hangers, etc.), as if one just ain’t enough?

Im new to flashlights and own a few.

What are the differences in drivers used in todays hi powered lights. I see FET, buck, boost, I don’t know what any of them mean, and why sometimes one is used over another. Help?

You must not have clicked the “don’t send me email promotions” box. I never get emails like that, yet I buy from them.