I was also disappointed in the stock driver - the high mode was barely brighter than medium in my sample. I couldn’t find any good multi-mode boost drivers small enough so I settled for a FET driver with a 14500 cell.
Put it in this morning and it works great. No moonlight but the low is a good level. It gets burning hot on turbo since there’s so little pill mass; I would ask Richard to put the timer down to 15-20 seconds if he can.
In case anyone stumbles across this, I was looking for a driver for the AA brass beauty and figured I'd try pd68's 14mm driver layout so I built one and it does indeed work fine. In fact it even fits with a tiny85v in place of the tiny13a, on the same pads - you just have to bend the pins under the body of the chip. Furthermore, a SOIC-8 programming clip still fits, too.
It's a single-sided 1x7135+FET driver with 0603 components but not too bad to assemble. Works great, though if you don't reduce the duty cycle for turbo mode it'll draw close to 5A from the 14500 cell I have, which is way too much for something with this little thermal mass. Though it's holy-crap bright for a AA light! I'll probably leave it in though there's some appeal to keeping the stock driver and being able to use regular non-lithium AAs. Fortunately it's really easy to swap back and forth.
