Flashlight for Flashlight Geeks

I have gotten off of my flashlight kick for the most part, but I still check in every now and then at Budget Light Forum to see what is going on and see if there are any major developments. That forum has really thrived. One of the things they have done is work with flashlight makers in China to come up with customized flashlights more like what flashlight geeks like. That includes things like very low firefly modes that barely put off any light at all. Or neutral and warm tinted lights instead of the bluish cool white tints that are usually used. The results have been kind of mixed, but some reasonably good lights have been produced, sometimes not very different from production models.

Meanwhile other BLF members developed customized software that controls the user interface of the light, not just the number of modes and levels of each mode, but hiding less desirable modes like strobe (but still available in case you need them). Or having the light remember the mode it was in the last time you used it (this works well walking the dogs because medium usually works best but I only turn it on sometimes so it isn’t good if it starts in low every time). A lot of the budget lights seem to have 5 modes which are typically low, medium, high, strobe, and SOS. Using morse code to spell out S-O-S, they don’t even always get that right. I have lights that were O-S-O or S-O-S-O. Honestly, who has ever been saved by a flashlight with an SOS mode? So these guys started reprogramming the computer on their lights to get only the modes they wanted and the levels they wanted. Everyone has slightly different preferences on modes, so this was a way to really customize a light.

The way a flashlight switch works is it usually just disconnects the battery. There is a little computer chip in the flashlight that can do things like remember the current mode, but the problem is the computer only runs while the light is on and the battery is hooked up. When you turn the light off, you also cut power to the computer. So the computer can easily count the seconds that a light is on, but cannot possibly count how many seconds the light is off since the computer isn’t running when the light is off. That’s a problem when it comes to switching modes because the usual way to switch modes (really the only way to interact with the light at all) is by turning it off very briefly and then back on again. So budget lights usually measure how much time the light is on. The light can count how long it is on and store that number in flash memory (not erased when the power goes off), then when it comes back on and sees a short number was stored, it knows to go to the next mode. But if it knew how long it was off, it would work a little better because if a light has been on for a while and you blink the power off, instead of going to the next mode, it will read a big number and stay in the same mode, as if it was off for a long time. A flashlight can remember how long it is turned off by including a capacitor in the flashlight that will keep the power running to the computer for just a second or two after the battery is disconnected (another way is with an electronic switch that keeps power going to the computer even when the light is off).

There are also some hotrodders who like to drive LEDs really hard to increase the light output, which you can do as long as you don’t overheat the LED. One way of cooling the LED is to mount it to a copper disk instead of the usual aluminum since copper conducts heat about twice as well as aluminum. And the hotrodders are figuring how to get as much current as possible to the LED using a low resistance computer-controlled switch called a MOSFET instead of running the power through the computer chip. The battery of choice is the 18650 which is used in laptop batteries and tools. If a laptop has a 4-cell battery, it has 4 18650 batteries in there. In fact, some people will tear apart old laptop battery packs to get the batteries out and use them in flashlights (and lately in electronic cigarettes). A lithium ion battery supplies just the right voltage for an LED. There are a lot of different types of lithium ion battery and if you putting a lot of demand on it, you don’t want to use one that has a tendency to catch on fire. So this light was designed with high drain, but still very safe, Lithium Manganese batteries in mind.

And they finally found a flashlight company to play along with them and use their favorite really bright but neutral tinted LED’s, mounted to copper boards, using the driver they developed with the capacitor and MOSFET on board, and running the latest software, all the technology developed by the members as open source. The result was the BLF A6 flashlight built by a company called Manker. It still had some hiccups. The springs for the battery should be really thick to carry a lot of current with very little resistance, but a spring made with thin wire was used at first. And some people wanted a nice clip, but weren’t crazy about the clip that was being used. They got things worked out around the time I was checking in again, so I definitely bought one of these lights. For the uber geeks they even came up with a special edition made of bare aluminum that I thought I might get if everything worked well on the standard edition light.


The software is pretty neat. When you first get the light it is set to 7 brightness modes (no SOS or strobe!) and always comes on in the lowest mode. But 7 modes is a lot of modes to cycle through. So to make it easier, the software times how long the light is off using the capacitor. If it is off for a half second, it comes on in the next mode. But if was off for a little longer, a half second to one second, then it goes backwards one mode. So if you want the highest mode, you do a long press, the mode goes back one and you are at the maximum again. If you do a bunch of half presses in a row you can get it into a program mode where you can set the number of modes to 4 instead of 7 (I picked 4) and whether you want mode memory (I do!). If you cycle backwards enough times, you eventually get into the hidden modes which include a strobe, a special bicycle strobe, and a battery indicator that blinks from 0 to 4 times depending on the battery strength. So the computer can monitor battery strength somehow. That’s good because the light dims itself as the battery starts to get weak, letting you know you need to leave the vampire’s castle NOW! and giving you enough time to do so.

About a thousand of these were sold. Then the company stopped making the BLF version and made exactly the same light but called it the Astrolux S1. It’s a pretty neat light with a complicated, but flexible and useful user interface, a hard driven LED for amazing brightness, and a really nice tint for snobs like me who worry about that kind of thing (actually they made 3 versions of the light with 3 different tints: warm, neutral, and cool).

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