- The code I posted is to test the behavior of the FET with a partially charged gate. Quick & dirty way to see low output. Don’t leave it running too bright too long.
- Plan B: It can be integrated into other firmware for low modes, with some difficulty.
- Plan A: The hardware can be changed a little to get similar low modes with slightly modified existing attiny13a firmware. The resistor value can be approximately worked out from behavior of the code I posted.
Plan C: Use lower PWM frequency. Also complex but definitely possible and with no hardware changes. Has risk of visible PWM eventually. Might eat up valuable firmware space.
The major unknown is how much the results of A & B will depend on part variations. I’ve not done enough testing to have any clue. It could be that each driver must be flashed with different settings to get the same output. I think that would be annoying but still better than no low modes at all.
Yeah, some clarity about output expectations for 1xAA or 2xAA would be nice. Also, I don’t know anything at all about driver development. Does this need a custom firmware written for it, or do (any/all) the already available Tiny13 firmwares work? I’ve been trying to follow along, but I’m way over my head.
That is a very interesting approach, fixed it, thanks for posting! Most spend their time trying to bypass triode, not linger in it. Like you said, it'd be interesting to test what kind of dissipation occurs if you drive it that way and whether the trade-off in efficiency is worth it.
This isn’t about high power. Output remains the same and is limited by the power handling ability of the boost ic to ~1A Max or lower by choice of sense resistor. What’s new is the addition of the Attiny 13A. This opens all the AA and 2xAA cheapo and not so cheapo lights up to mods without annoying strobe modes or with modes of choice. Non muggle modes for muggle lights.
It’s time for some field testing.
I just built a HQB15 v2 and installed it in a Sipik SK68 clone.
First memorable result: A swap of the FT driver will need additional capacitance (higher C2 or additional C3).
I did at first a straight transfer of only the FT parts and got only initial flickering. Like: strobe for half a second. Same after every mode change. I changed between different driver frequencies, still just flickering.
The FT driver had 10µF as C2 (10.7µF according to DMM, I tested it after harvesting the part). Added a 10µF 0603 (tested 7.8µF) as C3 and - voila - the light stays bright in every mode.
R1 is 0.120 Ohm (R120), no ‘overclocking’ for now.
Flashed is the already mentioned adapted MiniDrv with 3 modes (PWM 1,8,255), with on-time memory (no OTC).
I started with 4.7kHz (9.6MHz, fuse 6a (divider:8), fastPWM) and now flashed to 38kHz (9.6MHz, fuse 7a (divider:1), fastPWM). Both work, 4.7 is whining considerably and has higher low, 38kHz is silent and slightly better at PWM1.
Let’s see how it handles some heavy use. Pics later.
Edit:
Of course I swapped for a BAT60A before installing into the SK68, as the original diode was only attached by wire.
I successfully built one HQB15 v3 and one HQB17B v1, which both are running fine in lights. Still with simple firmware, I tweaked the MiniDrv firmware with several mode groups which took me a lot of time.
To be honest I at least postponed the idea for LVP. None of my AA light has it and I can live with a dead or degraded eneloop once in a while. I just won’t find the time to dig deeper here. I will finish the planned 17mm LVP boards (C/D) so if anyone else wants to progress LVP he has something to go on. Just ask if you need a certain layout.
I started working on HQB15M and this one looks really promising in Eagle so far. Made me chuckle more than once. I redesigned my Attiny MMU breakout board and that took me a while, but now it all might get into shape.
Using the Attiny13a-MMU would even allow for sub-15mm variants. Just sayin’
I’m hoping at some point these boards will be sold ready to go, Mtn Electronics is the obvious seller, but a source in Europe or Asia is easier for us overseas.
Hmm, I really hope that Richard get his boost driver succesfully running and for sale…
Today I hoped to mod a BLF X5 (the OL-engraved one) with a boost driver to get it working on Eneloops (I’m sure that Old Lumens will approve that, he used to be not keen at all on using li-ion cells), so I tried an LD30 that I had. Unfortunately, the three modes on the XP-L Hi led are as badly spaced as can be: 1lm, 120lm, 135lm, can’t live with that
On the bright side: to my surprise the X5 with the XP-L Hi at the very modest 135 lumen is a very nice and useful flashlight, it is not as impressive as the 1300lm of the stock X5, but its good throw makes it still a powerful flashlight.