adam7027. What you are wanting is a buck or boost driver like we have been talking about. These are fairly easy for low currents but get exponentially harder as power goes up.
Also, while the linear drivers are less efficient at low modes then a buck/boost driver, it is usually not enough that you would notice it besides a bit less battery life. It is not enough to make the light noticeably hotter to the hand anyways from just an emitter swap.
As the improved efficiency of the emitter makes up for the worse efficiency of the driver, so the final output is basically the same. You just don’t gain efficiency that you could from the lower Vf LED.
In my testing of linear / PWM drivers, even at 50% duty they were still close to 90% efficient, which is about what you can expect for a buck/boost driver. Only in modes lower then that will there be a noticeable different in efficiency.
Although the linear driver gets more efficient as the voltage drops. So in the long run the final outcome is not nearly as bad as it sounds on paper except for some special use cases (very long term use at very low modes for example, where you battery life is measured in days).
Good to know about the higher resistance, I didn't consider that. Still, if you know premium single cell buck or buck-boost drivers for d = 17mm, I would happily take a look at them. There is a chance, that in some less frequent cases, I would like to use emitters comparable to E21A quad, regarding the Vf (e.g some monochrome reds are of much lower Vf starting around less than 2.5V).
I also noticed the small room for regulated output with the stock Skilhunt H03. It 'lost' its highest setting around 3.8V, while with the E21A quad, it could go down to 3.3V with a plain old Pana NCR18650B for the same effect. Something approximately as good as that driver could be good for me.
Otherwise, if I'd use a linear driver, maybe then it would be better to use some mid-current, capacity optimized cells to make the difference a bit less, and their discharge slope also gets less steeper at the second half of the discharge.
For what current level would you consider a buck (or buck-boost) driver to be fairly easily made?
I found somewhere a driver, which could fit most of my use cases /no blinkies, more modes relatively close to each other in the midrange - I planned to use it with 4-5 pcs of 7135 regulator/, but I found a review, which had discouraging results for me. Based on the fact, that it was made with a Cree XP-G2 emitter, I only expect worse result with e.g. Nichia 219C or 319A - that was the main reason for me to ask for help.
Are there 'good' and 'bad' (i.e. with significant difference) linear drivers, according to your tests?
Thank you, I already looked at that specific driver, just hoped for other solutions as well.
But the fact, that it 'renders' all modes without PWM, could be good.
Buck/boost drivers are reasonably simple to make with up to ~2-3A max on either the input or output, whichever is higher. Once you go much above that it gets exponentially harder to keep everything in check.
The 7135 drivers are fine for what they are, basic and cheap but they do the job.
How about a buck driver that fits an L6, with narsil, and 12v 2.5a output. I’d love to build one with an xhp35hi. I would be happy to use 4 x 26350 in it. Slightly more reflector over the l2 version and ramping fw. I would hope for a bit better throw over the l2 for that reason.
I was thinking zener modding a fet setup, to get the input side sorted, but i have no idea how i’d regulate it to keep the led at 2.5a. Buck seems like a better plan, but i don’t see them done on that platform.
You will need to see Lexel about that. I just recently heard he got some help to get NarsilM working on his high powered boost drivers. No word on when they will be available, though. I hope soon.
Iirc, Richard doesn’t use NarsilM. He may adapt RampingIOS (the D4 UI) to work later on, though.
So, do we need to take up a collection for you guys? I’d be happy to throw in a couple bucks to push the boost driver forward. I figure there are others who would do the same.
1. 1S Buck-Boost Driver for 2.8-4V LEDs which does up to 5A, but it configurable down to 3A. Controlled by eswitch with many low modes (like Zebralight), overtemp and overdischarge protection. Maybe also a version for clicky switches. [/Quote]
I just found out here that Zebralight used the TI TPS63020 buck-boost IC in the SC62. It does up to 3A from a single Li-Ion.
I would love to have a similar driver as an aftermarket part, especially with an even higher led current.
This TI chip can go down to a Vin of 1.8V, so it can also be used to drive UV LEDs (at less than 3A).
The TPS63027 looks like a good candidate because it can deliver a high output voltage of up to 5.5V.
The MAX77816 might be another good option. It can deliver 3A in boost mode.
I would be looking for a 1 cell boost driver. But I just started building and flashing my own drivers, therefore I am not a useful contributor or not to the extent like the pros on here.
Not sure which emitter should be used either, maybe a 6V one and some good amperage behind it (around 2A-3A maybe?).
