Driver Hunting... Yezl Y3 + XHP50.2 + E-Swtich

I’m looking for a 7135 linear driver with a zener mod to run a 6 volt XHP50.2 in a Yezl Y3 with 2x 26650’s that has an E-Switch and just haven’t been able to find one.

Does such a thing exist?

There is a 22mm opening for the driver, and the e-switch sits on the board.
Pictures here: Yezl Y3 - a picture breakdown

I am happy to use a 17mm driver and stack things like Tom E did or try to make a 22mm driver work, but I can’t go bigger than 22mm.

Is it possible to make either of these E-switch capable?
QLite 6V+ Zener Mod
BLF 22mm 16x 7135 6A

Thanks for any insight.

Yes its possible( but quite useless, my opinion)- MNT has it, youll need something like TK ramping firmware OR Dr. Jones one, or else
Its ways better to use a zener fet driver though

Stacking 7135s is quite not recommended: they do temp throttle you know

Thank you for the quick feedback.

I’m seeing in most of the notes that it is not recommended to run the zener mod and the e-switch together. Can you clarify this point please?
I’m not sure it applies considering I would plan to use the tail switch to cut power and the side switch to cycle H-M-L like my currect driver hopefully.
I’m referring to something like this? FET Driver - 17mm
Would this be better? FET Driver - 2S+ Momentary - 17mm / 20mm

I wasn’t sure if it was such a great idea to direct drive an XHP50.2

Is there another driver you’d recommend for this light?

Zener mod leads to a lot of parasitic drain (40mA or so?). If you aware of that and lock it out with the tail switch it’s not a problem.

The xhp50.2, with its low Vf, has made driver choice a bit awkward. 7135-based drivers will produce a lot of heat, possibly too much. FET drivers will result in a lot of current with fresh batteries. Prob not enough to kill the emitter but enough to be inefficient and get really hot. I would prob recommend a FET driver, but be aware of the above fact and maybe use turbo mode sparingly at least until the cell voltage goes down a bit.

You can read more about this in some recent threads on the XHP50.2.

FET it is, sounds good.

So in an ideal world I’d use the rear clicky for on-off and have an e-switch that cycles through 50% - 20% - 5% with no OFF in the cycle. Then I would like a double tap to get into 100% mode. I’m doubting something like this exists in a 17mm 2s format. Anyone know of anything?

You really want an LDO driver. With a zener using an e-switch, you'd have to consciously turn off the power switch when you stop using it. DEL has a great custom designed driver just for the Y3 here:, which I've used, but unfortunately no LDO capability.

I need the same thing myself for a Yezl Y3 - exactly what I want to do - XHP50.2, 2 26650's.

We could try talk'n DEL into making us one

K, just asked bout it in his driver thread - see what he says. Probably more likely if he's interested in the same thing, not sure he has an extender tube though.

should be no problem to modify the TA 22mm LDO driver with an eswitch glued to its side

Possible. I'm using the TA 30 mm LDO in a Convoy L6 - awesome!!

Tom E thanks for the insight. I’ll go the LDO route if I can’t find exactly what I want. I actually think this driver would work well with the moppydrv firmware in mode 6.
2S FET Momentary

My thought process was that if the E-switch didn’t have an off in the cycle, then the zener parasitic resistance wouldn’t be an issue as you’d be forced to use the clicky just like the stock light. Likewise it would ideally power on when the rear is clicked prior to any e-switch activity.

My idea of the double clicked turbo would essentially be to have the stock interface and light outputs until you double click the e-switch, and boom.

So instead of the stock 900, 400, 80 lumens or whatever it is you’d get 900, 400, 80 [4000] or something.


Narsil is the most advanced firmware you can get, you can set so many things
plus if I make your driver I can set the mode spacing programming in the code as you wish if you dont want to use ramping

Some guys like the tail as ON/OFF but I much prefer having full functionality on the side, but that's my preference. Certainly these drivers can be programmed the way you want, just dunno if you can buy it that way - maybe Richard would do it for you.

Edit/Update: DEL is on the case. Has a nice LDO version for the Y3 driver already. We are working out providing the indicator LED an easier setup for mounting.

Once he finalizes this, I'm definitely ordering them.

Oh nice, thanks for the follow up.

Well you helped me out by bringing this up in the first place