The There Are No Stupid Questions Thread

So both are CRI90 but one have more red reproduction? Is that it?

The 2nd one, R9050, has less red representation. Without the rest of the analytics, I would infer a greener tint. But the overall balance is in the 90% colour rendering. It could have also more yellow or another artifact. Generally, Nichia’s are known for their good emitters. It’s white wall hunting and side by side comparisons that demark the small differences. With time, your eye can see these individually.

Yes, both 90 CRI

@story, the answer is yes, as the battery packs will still be pushing about the same amount of power, which means current pushed to each LEd will go up a bit.

Ah ok! I get it now. Thanks!!

Thanks.

I have TrustFire TR-3T6, can I reflow 3 SFT-40 to replace the CREE XM-L2?

Would add that although 9050 and 9080 are both rated 90CRI, the 9080 is closer to 95+ CRI in practice. Some higher CCT 519A's (rated 9080) measure above 97; even seen one measure 100.0 on an Opple meter.

That should be possible. The XM-L2 is a current sensitive led just like the SFT40 so most likely the current of the flashlight will be somehow limited. You should use copper DTP MCPCBs, though.

Can anyone give me some basic information about the driver this light uses?
https://www.aliexpress.com/item/1005001973586200.html?spm=a2g0o.order_list.0.0.21ef1802cLfTQV
Convoy C8+ with KW CSLNM1.TG and 12 group driver.
(I own this light)

Is this whats called a biscotti driver?
What is guppydrv?

Need someone to point me in the right direction here.
Thanks

https://www.aliexpress.com/item/1005002639038647.html?spm=a2g0o.store_pc_groupList.8148356.47.6f605518E5de3v

Is this a “boost” driver?

His 12-group driver is not Biscotti but it’s highly derived from it. Back in the day, ToyKeeper made the Bistro firmware, and then later trimmed it down a little to make Biscotti just for Simon. I don’t know if he’s still using Biscotti on anything but maybe…2-3 years ago he had some issues and then developed his new 12-group, very similar to Biscotti in features.

Dr. Jones, TomE, and ToyKeeper (and others) designed several of the popular firmware programs years ago, many of which are still used today. Probably a lot to wade through, but a forum search for each will tell you as much as you want to know. Richard at Mountain Electronics still offers lots of them and has good quick rundowns of each. Take a look at his drivers and scroll down to where he describes the firmwares offered…several have a separate page that you can click the links to read more about (features and operation, sometimes more). Here’s one that has most of them listed: 26mm FET+7135 Driver - MTN-26DDm - 1S Input Voltage

As for the driver in your light, he says down the page that is has a max of 4.8 amps (4800mA), and he also says the light gives about 1100 lumens with that emitter. Measurements tell the truth but Simon is usually pretty accurate and he lists out-the-front actual lumens rather than paper lumens (those being a theoretical max based on component specs, not accounting for efficiency or losses from resistance, reflectors/optics, lenses, etc).

If you were to browse the data sheet for that emitter, you might expect the driver to only be delivering around 3.5 amps for the stated lumens and with the bin he has chosen to use, but again, all that extra mumbo jumbo reduces actual light output from theoretical. I assume the bare emitter he’s selling separately is the same as what he’s using in the lights (that’s usually the case), and if so then he’s picked one from the available bins that has a bit lower lumen output, but it also has a lower required voltage and a better spot in the tint chart which reduces the green a bit. This is what he usually does, picking one with a good balance of performance and light color, rather than playing the numbers game for max-advertising-lumens.

If you want to browse the data sheet for that emitter, here’s a link. Even if it’s all greek to you, it’s fun to take a look and I know when I first started doing so it actually helped me understand a couple things, and then I started to explore all the other things I had no clue about, and understood more after that. If it produces more unstupid questions, post ’em up. lol

And Simon’s link to the emitter, where in the title description you can see the binning information (model)….which is 6N for “brightness group”, 15 for voltage group, and ebxD46 for chromacity/tint group (pages 4 and 5 on the data sheet): https://www.aliexpress.com/item/4001238336707.html

@Correllux
Thank you very much!
This is a lot of good information for me to work with.
All very helpful to me right now.

Is it a boost driver though?
Im wondering what makes it different than the “regular” convoy drivers.
Its “designed specifically for the 12v GTFC40 LED.”

So is it “boosting” the Cells power to meet the LEDs requirements?

Im mostly just wondering if its a “better” driver?
Boost is supposed to be more efficient right?

Its not critical informaion I need. Just curious and trying to learn.

Yes. A magic one.

He gives the numbers that help you know….Input and Output.

Input is 3 to 4.2 volts, which is what’s normal for a single lithium-ion cell.

Output is boosted alllll the way up to 12 volts! Woohoo! And at that voltage has a current of 2.5 amps.

I’ve always thought boosting was a little magical. It’s easy to grasp the idea of a buck driver, where “extra” voltage is just diverted and wasted as heat…like flattening a heaping scoop of coffee grounds (which is sinful). But making more out of less is pretty special…especially when bumping it up to 12 volts instead of the much more common 6 volt boost needs. This is chosen by the particular emitter, of course.

If you look at the photo of the top side of the driver, that big grey square is an inductor, and that along with some other components is making it all happen. Some inductors look like little black cylinders, maybe with a black shrink wrap around them or maybe without, allowing bare copper wire winding to be visible…and some look like little glittery charcoal briquettes…lots of different types of inductors and they can be used for both buck and boost purposes (either/or, or both at the same time, depending on the circuit design).

Now on the flip side, take a look at this one from him…it’s a buck driver but it looks very much alike: 6.44€ |17mm fahrer, eingang: 3 8,4 V, ausgang: 3 4V 1200mA (single mode)|Taschenlampen| - AliExpress

That one tells you that the input is from 3 volts up to 8.4 volts, which would be the voltage of one single cell or two cells in series. Since normal 3v and 6v emitters will likely go poof if you press 8 volts into them from two batteries, this driver bucks off that extra higher voltage to regulate it into something that protects the emitter at a normal 3-4 volt range (the voltage an emitter uses is variable while in use and depending on current and binning, within a small range). Big fat square inductor but it’s being used for a different purpose here (it’s no doubt not the exact same spec inductor as on the other driver, but just as an example of the dual-purpose).

Here’s a pic of a different old-school kind of inductor, still popular in many designs and devices: 11.3€ 5% OFF|Super Output SSC P7 Led treiber Bord (Low/High/Mitte, 5,5 V ~ 15V)|board|board boardboard led - AliExpress

And an even older-schooler inductor with a fat iron donut wrapped with wire: https://www.aliexpress.com/item/32760098085.html

All this inducting business is the magic of magnetism, by the way…same as in A/C motors and many other electrical things. The energy in naturally produced magnetic forces is built up or torn down to different levels and used for world domination.

Tidbit: Dr. Jones designation of Guppydrv & Moppydrv from the names of his cats. The ‘drv’ being shorthand for ‘driver’.

Awesome!

Thanks again for all the information Magneto

Aha, thanks

Just saw your post…typing that long reply. lol. Different driver than what is in your C8 with the Osram…very different. Your Osram is a normal 3v emitter, so no special buck or boost needs there. However, in some more expensive/complex drivers (and lights) a buck/boost driver is used even for the 3v emitters just because they are more efficient and usually also because they can better regulate output for more consistent light in at least some modes. It’s all a balance…if you want consistent light then you have to work the magic because the power from the battery is not constant like from a/c power or if using a really giant battery with huge capacity. So if a fully charged cell is at 4.2 volts but your emitter only needs, say, 2.7 or 3.2 volts at a given mode, then the buck part of the magic can run it more efficiently and with less heat, giving you better run time from the battery……then on the flip side when the battery is depleted enough to not be able to give the voltage needed, the boost part of the magic can do its thing and keep the light running for awhile. It’s a great design but they are kinda rare these days (easier to find them in expensive lights than it is to just find the drivers for sale separately).

So in picking a driver, you first need to know the power source voltage delivered, and then the driven component voltage requirements…and go from there. One cell (or cells in parallel), two or more cells in series….and if the emitter(s) you want to use are 3, 6, or 12 volts (individually/parallel or in series)….then whatever else you need. Without buck or boost magic, you just work with the battery voltage as it falls, and small simple components like the 7135 regulator chips will do what they can until they can’t anymore. Buck/boost opens up many more options (which is great if power source is limited, like one single cell, and of course the other advantages no matter how many cells are being used).

lol, I thought you had a pretty lengthy response in such a short time.

All good though. I got a bit confused there for a second. I have an M21B in the mail with the GTFC40.
When I quoted you ” As for the driver in your light, he says down the page that is has a max of 4.8 amps (4800mA)”
I was thinking that was referring to my M21B.

So it all made sense to me anyway. No confusion.

8th grade typing class was either the best or worst thing I ever did. lol

I didn’t know that about the driver cats….that’s cool. I’ve wondered whatever became of Dr. Jones.

He spends his time doing cat-scans.

What kind of shield or filter is enought good to block the blue light emitted by LEDs? If I’m not mistaken I had read that the milky plastic that covers the bulbs has good shielding, really?