The design of the driver is not considered for continuous 5V power supply. In fact, your requirements are beyond the scope of flashlights. I personally think that there are not too many buyers who have the same needs as you, which makes me a little hesitant.
@Discharger Just a thought, if you buy the emitter, you can whip up something that uses a standard 12V PSU and add simple PWM control (lots of cheap boards out there). Probably more efficient too.
I’ve ordered a few Convoys recently, and will do a mini-review of all 3 in one article when they all arrive - M3-C XHP70.2 5000k, S21D 519A 4500k, and T4 SST-20 6500k.
Simon, I agree with you that my requirement is in fact beyond the scope of a mere flashlight.
It would have been a great bonus, however to be able to use your flashlights in this way, especially since with the 1800K-2000K GT-FC40 they would constitute a portable source (for continuous use) of light of a desirable quality for night use (low CCT, high CRI), possibly eventually resulting in more sales for this use case.
Personally I am not desperate to use an M21F for this purpose, my needs are already served quite nicely by Soraa Vivid 2700K with four 3/4 CTO Snap filters yielding light with a CCT of 1850K and CRI of 98.8
But I digress…
It would have been nice if your new GT-FC40 driver was able of continuous 5V power supply. If it can boost to 12V a power supply of 4.2V (or less) it really should be able of boosting to 12V a power supply of 5V without fundamental design changes…
That is good news! Ordered 1 the moment I read this. This allows me to do some comparing without spending too much money (more left over to spend on M21D or E or F ;)). Last night I discovered I have an S2+ with 3/5 driver that appears to have no coating at all, so all 3 types are covered then. Just need to prepare 3 emitters from the same reel to make it a fair comparison (or take the pill out a few times to swap the lens).
My guess is that the low power without a battery is because of the way the voltage is being read with the boost driver running and no battery. The charging circuit probably thinks it’s almost fully charged so it lowers the current. You could probably use a cheap protected 18650 and run it at full charging power without having to worry about the battery over discharging.
Actually it would be somewhat of a fundamental design change. Heat and duty cycle are your important considerations here, and that applies to the actual power source as well. Sure it could be done but at higher cost and possibly with difficulty considering the space constraints of most boards/space in the host. Even at a low current they just aren’t made for 100% duty cycle. Considering wall warts, some may handle it ok, some will die, some may die with aplomb. From a manufacturing standpoint, unless you were to include a dedicated power source and insist that it be used over other product options out there, it’s a risk. Better to just use products that have a suitable topology.
Yeah, I’m curious why it “must” be a flashlight and/or flashlight driver, vs a dedicated area-lamp or something.
Anyone who ever designed a switcher knows there’re a bunch of constraining parameters on max/min input voltage, max/min switching frequency, inductor selection (L/R/Q), etc., that all involve tradeoffs. Otherwise, there’d be one all-great reference circuit that everyone and his grandmother would use.
Enough talk, let’s experiment already. Ultra crappy moodlight test
Disclaimer: there are no safety precautions whatsoever! Turning it up too much will burn down your house….
On a more serious note. With proper heatsinking/limiting, this might actually be a nice FC40 1800-2000K project. Or modify a real lamp to use instead of a regular bulb.
I might be tempted for M21F with GT FC40, but does anyone know what CRI are the M21F XHP70.2 versions are (70CRI?).
Are there any plans for M21F on XHP 70.3 HD or HI, with 90CRI available, are they really that hard to source?
Any plans for T4 on 12/13 mode driver?
Thanks for such an illustrated answer. Guess that means no 11 mm hole reflector for the L21B.
