My work here is done.
While you’re spending money, these can make you cry a little. BRM is known for flex-hones but they make all kinds of stuff. These mini tube brushes are hands down the best you can get and there’s just no comparison to all the cheapies out there (if you can find them in these small sizes that aren’t the wimpy soft nylon type for paint guns or carburetor jets). Looks like amazon is out of all of them but they make them in SAE or metric, stainless or nylon. I grabbed a set of each in stainless when they were at bargain prices of I think $38…yay covid stimulus. But gosh darn am I glad I got them. Haven’t needed them for lights of course but just general shop tool stuff. The pin vise that comes with them is the meh type with two double-ended collets but fine for this use.
!https://m.media-amazon.com/images/I/91IDFp-5rCL.*SL1500*.jpg !
Add some Nyogel for threads and ya got a pretty good little kit there
Thanks for the tip, but fortunately for my wallet they don’t seem to be available anywhere that I can find. 
Thanks CollectEverythjing for looking but yes, I found the same unavailable listing.
Nice set. If I had other uses for these, I’d likely pick up this set. I might have to hit Harbor Freight and see if they’ve got a smaller subset for less.
Yes! I actually have a tube of Nyogel. I also have a gel lubricant designed for o-rings of pool pumps, which also works. But the Nyogel is slightly more fluid and spreads nicely. It also seems to last longer.
I just so piggybacked some 7135s onto an MTN 8x to make 12x. Worked for some seconds then dropped to very dim.
Did I overdo the MCU’s driver capability? I had also changed the cap from 38µF to 22µF as I was double-clicking for mode advance.
➜ 
The cap went open circuit so I returned it to the original value – same outcome.
What is the attraction of having a fully regulated light which keeps the brightness constant as cell drops the voltage? Isn’t the “missing” brightness just burned as heat by the 7135 regulator as “virtual resistance”? I am talking about single lithium cell based lights which are the vast majority at least when we discuss them here.
Regulated means more consistent. Unless you got a buck or buck-boost driver for more efficiency, the regulator approach just means more consistent light, vs brighter at first and then dimming as the SOC decreases. It’s still a resistance either way, constant with the cheapies, variable (to maintain constant brightness) with linear regulators.
Plus, you don’t have to worry about lower brightness with a high Vf LED, or cooking it to death with a low Vf LED, or the state of the springs, and high- vs low-drain cells, etc.
Is there a ramping driver for the L7 SBT90.2?
This may sound like a stupid question for some folks here, but it’s something that has been bugging me…
A battery has an anode (-) and a cathode (+) end. In order for power to flow, a wired connection of the anode AND cathode into a circuit is required. In a metal body flashlight, the rear spring connects the anode and the driver contact pad or spring connects the cathode. A switch is in the path, which can open and close this circuit.
So, when you do a physical lockout of the flashlight, you unscrew the end cap or head a bit, which ends the compression of the battery against the 2 contacts. Now there is a gap. And so, one would presume that you’ve got a physical lockout.
But I realize that this isn’t totally correct. If the metal tube threads are not anodized, the connection isn’t broken. There’s still a circuit. This is what puzzles me… as there is no longer two contacts touching the battery. There should be no power to the circuit.
HOW is the circuit being made?
EDIT: Due to tension requirements, most flashlights will make electrical contacts to the battery at the very start of end cap screw-on installation. With screw threads not anodized, as soon as threading begins electrical contact is made.
You unscrew the tail if it is anodized then there is a break in the tube rim to switch. It is not the relaxing of the spring / compression to the battery. A quarter turn doesn’t disengage the spring pathway.
If the tail end isn’t anodized, there is no physical lockout (less you completely unscrew the tail).
It doesn’t. In some light the springs touch the cell’s terminals even before the tailcap touches the tube.
Yes you can’t have mechanical lock out with non anodized threads, or brass/titane/copper lights.
Yes, I get that with some flashlights there’s contact at the very start of thread screw engagement. Eyeballing it with two of my lights, I thought there was enough of a gap. In principle then, is it very common practice for the contact engagement to start very early?
Yes…depends on the light, though (overall length, spring length, etc).
So…the energy “exits” the negative end of the battery and goes into the spring/switch. It passes the switch and enters into the metal of the flashlight body, traveling through the body up to the ground connection on the driver.
Anodizing serves as an isolator so that current (at normal levels) can’t pass through it. Just like it was paper or plastic or some other thing that doesn’t conduct electricity…but in this case it’s the magic of chemistry that deposits a layer of non-conductive stuff on (and actually in…) the metal.
So the battery is isolated from the inside of the tube by its plastic wrapper…and the insides of tubes are usually anodized as well. The current can only escape through the battery’s + and - terminals.
So…why doesn’t the current pass up through the host metal to the driver when the tailcap is unscrewed a little? That anodizing again. Look carefully at the ends of both the tube and the tailcap. You should see bare exposed metal on the flat surfaces where the two meet and touch when the cap is tightened. The threads on one or both are anodized. So the only place the electricity has to flow is “through” the tailcap metal and into the tube metal through that small flat bare-metal contact point.
If the threads on both cap and tube were not anodized, then the electricity could flow any time, wherever the path of least resistance may be. So unscrewing the cap in that case does break that flat contact area but since the threads are bare, juice still flows. Anodizing prevents that bare metal-to-metal contact on the threads, so the only place left is that flat contact area. And when you unscrew to make a gap….juice can’t go anywhere.
Not all lights are like this of course (beyond just the presence of anodizing), but this is the norm. Some ultra cheap lights don’t work like this and then some complicated lights like the “signal tube” design of the FW3A and Noctigon/Emisar lights don’t work that way either. And some lights can be locked out via the head threads, but some can’t (basically the same reason usually).
I don’t know if this link will be of any help since I think you get the basics already, but scroll to the third graphic…a light that says “battery” and shows the flow of juice. Doesn’t show all the stuff you just asked about but just in case: Deconstructing a flashlight | Deepak Kandepet
The exception is: Emisar has the tail spring on a PCB so the batt-neg is not electrically connected to the cap material, the battery tube screws against the PCB to connect with the batt-neg. In this set-up mechanical lock-out by unscrewing the tail cap works for all body materials and anodisation state.
Ah indeed I didn’t notice there was no contact between batt- and the tailcap, that’s a good solution.
I have no working knowledge of electrical components but have flashed an Emisar D4 once. That being said, why can’t we just flash all drivers to our liking? I know that a MCU has limited capacity but surely there are some firmware(?) out there that will fit. I don’t know how standardized MCUs are though with regards to pinouts if that’s the issue.
How do you know if the MCU is flash-able anyway?
For the most part we only work with the ATTiny MCUs. They aren’t that common anymore, except with manufacturers that use them specifically to support our firmwares.
In addition to being able to identify and work with other MCUs, we’d have to know how the circuits are controlled by those MCUs - though that can likely be “probed” out by someone with enough expertise