Several are probably familiar with the FL-2 and its siblings. HKJ review of a 3A small torrid version here. Links to several shops selling them. RMM might be getting some with low voltage cut off for 3 cells too.
Tom E and many others have used these in BTU shockers and similar lights. These drivers become direct drive on high when you have the same amount of cells in series as emitters in series.
Heat, possible issue.
When direct drive they don't product much heat since they just "bypass the amps." When regulated and working as a buck driver they can fairly easy overheat if they don't have adequate cooling. The higher the output, the more cooling needed. I did some torture testing on one of mine out in the open with zero cooling. Killed it 5 times. Parts and wires fell off due to heat. it normally takes around 3 minutes to kill it. I just put it back togheter when it died, and it kept going. :D One time it smelled really bad when it died, I was sure that was it, but it kept going and strangely it still lives. With my little testing I killed it at 3A, 5A, and a bit higher, with small torroid and with large. You can resistor mod it for more than 5A, but they don't like it and easily drop output and act a bit funny as far as I have seen. (Sufficient cooling might fix with that?)
Recipe: How to make kick ass lights with a single FL-2 style driver?
BTU - 3s emitters, 3 series cells
Most get the recipe. It can be done in with several lights, and in similar ways in a bunch of multi-emitter lights. At least in theory. I have not seen many people do these... But there is no doubt there is many people who want stupid bright lights out there..
2 emitters, 2 cells
4 emitters (2s2p), 2 cells.
6 emitters (3s2p) , 3 cells
9 emitters (3s3p), 3 cells
12 emitters (3s4p), 3 cells
There are many more setups, but you get the idea. Sick direct drive setups are easily available in a bunch of multiemitter lights with configurations like this. Unless anyone beats me, ill probably do a 9 emitter light at later time. Setups like these makes multi-emitter MT-G2 lights way easier too if done correctly.
What if you want great output in a light where the emitter number does not divide nicely on the battery number?
Here is where it gets tricky. But first lets try some stuff.
Lets take a 2 series light , 3 emitter light as example. There are not many good driver options for this if you want extreme output.
You might be able to fit 3 x LD29. Im not 100% sure if it works perfectly inside a light, but it did seem to work halfway out of a light.. :p
(don't mind some extra wires used for current readings)
At less than 3A per emitter it will not be super kick ass though, and some lights can not fit that many drivers. it will also become a bit expensive...
The LD-29 can be resistor modded, but personally im not a huge fan of modding that driver. This setup would not be very convenient in a light with a bunch of emitters though. So back to the FL-2 style driver. A setup with two of those drivers could possibly work in a bunch of multi-emitters lights where a single driver circuit can not do the job.
2s emitter, 2s cells
4A (to each emitter) with green Protected NCR18650B (I did not think they would deliver that much)
Lets try a similar driver (modded to 3,9A) powering a single emitter.
Lets try and combine the two setups above. One driver in series with 2 emitters. One driver working as a buck driver regulated to 3,9A. (powered from 2 cells)
Boom, light... 3,93A regulated to the single emitter. 2,9A to each of the other two direct drive emitters (cells are slightly drained now) and at high load (5A+) its obvious that the direct drive output is not as impressive anymore. Still, this setup could deliver 10 amp totalt to the 3 emitters with fresh green Protected NCR18650B. Pretty awesome for a 2 cell light with some nice features.. And with the correct cells, it could deliver more. J)
Im not sure how large the difference in output would be in the beam with 1A+ difference in current, especially not when voltage sinks more and two of the emitters sinks more.
But if you had a 7 XM-L light, then the middle emitter could be regulated to say 3A, and the emitters around it could be direct drive.. J)
The issue is, this does not work. :_( Due to some sort of PWM interference??? When running the dual driver setup, the driver circuit powering the 2 emitters have some flickering issues on low and medium. On top of that, the modes got messed up, despite having the same modes in the beginning. One driver was suddenly on high, while the other where on low after several quick on/off startups..
The big question?
Is it possible to do some sort of master/slave setup and have this type of setup work??
Anyone have some genius thoughts regarding setups like these?
Close up pictures of the driver in the review thread.
