BLF22DD v 1.0 zener mod questions

Just wanted to make sure I get this right. For this mod I change out D1 for the “2000” (200 ohm, correct?) resistor. Then solder the zener diode across C1 on the spring side. Is there polarity to worry about with the zener diode? Pretty rusty on how they work.

Thanks in advance!

If it's the BLF22DD v1.0 PCB then you'll have to modify the traces on the driver to make it work. That is not a good PCB for zener mod.

The zener diode's line faces positive (we only want it to conduct, which in our case is a controlled short circuit, with once the zener's 4.2v avalanche voltage is reached).

I got a complete rundown of how to get my version 1.0 driver up and running with the zener mod thanks to some PM’s with Richard. It’s now happily cranking out light with an XHP 70 in the maglite I just finished. I’ll post pictures and a writeup in a day or two, for now just a couple shots of the modified driver in case anyone else needs to do the same thing.


And I suppose a couple teasers for the mag build are in order as well.

Looks great! I'm glad you got it working.