Lexels driver compilation

It will happen and be done right in any case… and I’ll wait impatiently :zipper_mouth_face:

Lexel, how many amps do you expect the final driver to allow through for the XHP35 and XHP50 then?

Lexel, you had troubles sourcing MP3431. MP3431GL-P is available at mouser. MP3431GL-Z is not. Is -Z needed or did they restock?

They were both out of stock a while back, but yes it just got back in stock. There's no reason to use the more expensive 3431 though unless you are actively using the ILIM pin, as opposed to the cheaper and otherwise identical 3429, which has always been in stock. :)

How about a DD board (boosted to the MAX) for an XHP 70.2 (21mm) FOR A GUN— No UI needed? Possible?

I asked Lexel, waiting to hear back. I built the Sofin 20.8mm C8 kit last week and though about this idea after seeing what Lexel’s TA Bistro board could feed the SST-40 I mounted— (8 amps) :+1: And with Lexel’s tail FET switch (capable of 20 amps), it could manage the on/off.

Could this future driver (that needs about 5 minutes run time on a VERY high drain 18650) be made as you are working on this other boost driver? Could this “magic” driver exist?

Stirring the pot :smiling_imp:

So you'd like a single cell 12A 7.5V boost driver in 21mm form factor with a single mode? :) Your battery will need to supply 30A or so, you'll need more than a just a standard host (contact resistances will be too high), and the thermal dissipation would require a very large (or actively cooled) host as well... which may negate the desire to use a single cell in the first place.

Wait… before I get the kabosh :confounded: — here me out.

This light won’t run MORE than about really, maybe 20 seconds at a time (just long enough to do the Gridwald X-mas light show— Version 1.) :sunglasses:

SO… given the Sofirn can be wired in 16g (with by-passes on rear and direct connect to the top of the front spring), and maybe use a serious MCPCB… CAN this “magic” driver be made???

OK, OK…

Being more realistic… given Lexel’s FET handles 20amps— what would be a DOABLE config for a DD board and (whatever) LED?

Again… NO UI needed and the light would be on a gun that lights up for (usually) enough time to get a shot or two off. So 20 seconds would allow for many shots in a field of pigs and that would be about the time needed for FULL POWER!

Maybe I wait for the final driver here, but thought if there was something in a hot-rodded (20A max) smaller C8 that would work for this specific application (on a gun), that I’d toss the idea out there. I’m SURE there are a few of us hunting types around BLF that would like to have something like this too.

Does it need to be a single cell? It seems to me that if you'd only like 20 seconds to a min at full blast, it'll be easier to use two good quality shorter cells in series to drive the XHP50 or so in direct drive configuration. The resulting driver will be far simpler, easier to make, and you will get a very decent output.

I made a drop-in replacement FET Tailswitch with 1mR ON resistance which requires no battery replacement and works very well for my GXB172 driver builds ^_^. (https://budgetlightforum.com/t/-/50404). The resultant switch is the same size as the regular one so no additional shims or adjustments are needed.

This combined with say two 18350s, a high quality build and an XHP50B should hopefully give the output you want (especially since this time we'll only need to draw about ~12+A from the batteries instead of 20A), or even more for XHP70.

Such a driver should be extremely easy to make too (far more than the switching drivers), and there would be absolutely no reason why you couldn't have all the fun firmware features you want as well ^_^.

I do not need a single cell… and you are on track here. :+1: But to clarify the scope:

Lightweight and C8 (44m) head. Highest output for about 20 seconds possible (but it would be nice if it could survive a longer time interval of service— especially since several short “blasts” of light might occur over a few minutes— thus building up some heat.

I have in the hand:

Sofirn C8S host kit (with 20.8 mm driver area)
XHP-70.2 LED
high drain batteries (20 amp and more).

I do not need any UI, but if I did have it I’d LOVE something like Mode #1 in Bistro (Turbo/off) to be select-able.

But anything can change with my list of gear on hand. I could de-dome (anything) and I’m really thinking that if the driver (at about 21mm can be loaded for OUTPUT— without concern for a UI), that this would be what I am after.

I like your description of a possible config here— can we push it to an XHP70 (with whatever batteries/tail switch then???)

One more post from me before I think we should move this to a new thread, since this is afterall Lexel's thread - apologies for going off topic for a while ><

Typically designing a system with clearly defined constrains is (relatively) easy! The problem comes when people start adding extra requirements and asks and features :).

Otherwise, suppose we have a set of requirements as follows:

  • Use 2S configuration
  • Driver be ~21mm in diameter
  • Designed specifically for driving 6V-type LEDs like XHP50/70/144 in DD FET Mode
  • Work together with low-resistance construction and FET Tailswitch
  • Extra modes and features are nice to have

Then it seems to me like a slightly modified existing DD driver like this (http://www.mtnelectronics.com/index.php?route=product/product&path=67_117&product_id=714) would work just fine and solve your problem. As long as it's configured for 2S operation, it's pretty easy to e.g. optimize the FET for best performance, and fine-tune the thermal regulation to produce a desired operating behavior, and we have the driver you want :).

Finally I do have to point out that I'm really not a huge fan of DD FET drivers since LEDs are not supposed to be driven this way from an EE perspective :p. It's pretty easy to get an LED blown, if for example one day someone comes up with a better battery with maybe slightly different chemistry and higher cell voltage, and very very low internal resistance, and this is coupled together with someone who makes a very low-resistance build. In the case of some LEDs, not too difficult to blow the bond wire. It just so happens that IRL with today's LEDs and builds, it all works out decently. :) LED4Power seems to make some proper high-power current regulated drivers, so that's more like the kind of driver which makes me feel more at ease and how 'FET drivers' should be done.

IF… two batteries can be used on a gun with high recoil (tapped together or whatever is needed) in this config— then I’m interested in this driver! THANKS for that GREAT advice— I will seriously consider it and further research this option- it’s a solution and I THANK YOU for it!!! :+1:

But, the boost drivers here are for the beloved 18650 (one, as far as I understand) and so I’d still LIKE to ALSO continue to look into that route— if we are getting close. Because when out in the field, switching two batteries is more difficult and I’ve read where with guns— it’s just a lot easier to go with one battery. And because I want to stay in the lighter weight (and smaller head) C8— I’m still keen on a driver solution for it that would fulfill my “hunting” needs- all things already discussed… considered.

And yes… sorry for the segway Lexel. But as we were discussing this on PM… here is more info from this “wildcat” head of mine. :beer:

With my Tail FET board you dont need a driver for DD, just a contact board

The MP3429 is rated 30W constant output while the 3431 50W, not sure what exactly is the difference but I would not gamble

Datasheets of both say exactly the same: “Supports 30W Average Power Load and 40W Peak Power Load from 3.3V”.
Though 3431 has an circuit with 50W consumption among examples. Just from 6V, not 3.3V.

Ok the difference is for the MP3431 to have programmable input current limit, which is good to set for flashlight use

Uh wait… hold on?? ?:

Are you (Lexel) saying I can drive the XHP70.2 (with just one 18650) directly?

I thought I needed a boost driver (or board) to get the power up from one battery (or even “turn on” the XHP70.2).

He means that if you just want to drive the LED directly (either 3V LEDs with 1S or 6V LEDs with 2S) with no modes in a Direct Drive way, you can just turn on the LED directly with the tail switch, FET or not.

Sorry, need more coffee…

- so for a single 18650 I can NOT drive an XHP.XX without boosting up to 6V— correct? Isn’t this why the “boost drive” is in the works?

Sorry guys, I am good at ideas and I do not mean to sound nuts. As I don’t (really) understand the chip problem Lexel is having (getting them), I thought IF there were something (he or loneoceans had) already in the hand (no UI needed- but to JUST boost- with chips IN the hand put on a 21mm board)— I could use it for my C8 gun light project (with my XHP70.2 and one high drain 18650) sooner than waiting for the final boost drive (and also act as a beta- I’d be willing to pop a few LEDs for the cause) :smiley:

received very nice Lexel driver, highly recommended

Those look like my NarsilD’s Lexel sold me for use in my C8Fs. I had to grind my retaining ring at about a 35 degree angle on the side contacting the driver to keep it from catching on those chips on the spring side. Dremel is your friend :wink:

Also, that negative LED connect point does NOT ground to the round outer trace (I found out the hard way)- So I ended up running a touch of flux on it to keep my solder from “running” over to the outer ground trace (outer ring). FYI

You can drive 6V LED with 2 18350 1200mAh cells without driver

Or wait for my boost driver which will be not cheap