Well, "constant" power is generally not the case with regulation, which is usually constant current. That's why it's worth checking the draw after running, say, 30min. The "singing" is likely the "PWM" frequency (switching for power regulation in this case) and it's a constant pitch since I don't think these use frequency modulation.
The reflector and emitters are not the same. I did a direct visual comparison between the TrustFire & SkyRay Rev2 without taking them apart, which I'm not going to do; you can easily see they are different. Sure upon a quick glance they look the same, but looking closer you see they are not the same reflector and emitter setup.
Could you tell us the difference in the beams that they both produce then?
Yes the beam profiles are different, I did compare them side-by-side; but I'll have to go back and do it again, I don't want to post the differences from memory, as I recieved 5 different lights that week. They are different though, that's why I looked hard at the reflectors and such to see why they were different.
When I get back to the house, I'll take another run with them side-by-side and post again what I see as to the differences.
I'm back at the house now but we are having an awful storm outside, however I just did the white wall test with them side by side and the SkyRay has a larger hotspot and spill compared to the TrustFire....I hope that helps.
My 2 cell version arrived today in surprisingly perfect condition considering it came all the way from China in a paper package with a little bubble wrap. Happy to say it fired right up. Can't wait till tonight to compare it with my Fenix TK35
atbglenn.. please.. post tailcap current readings!
2.2 amps with freshly charged xtar 2600mAh 18700's
thanks. so it's more or less what the users on thaicpf reported
Mine is 2.0A, same with the 4 major brands. 4.20V XTAR/Solarforce blue letterings/Panasonic 2900/TF Flames (and actually the BIO IMR 18500/18350 as well). There is going to be a degree of error from the DMM voltage drop, but then my Sky Ray SR3800 got me 2.55A with absolutely fresh 4.21V batts. I guess there is going to be this variance thing from the factory.
Anyway, do try to use some thermal compound, there are 3 places which touches, the front edge at the reflector, the threads, and the part where there is a sort of ledge which the drop in presses down on the host when screwed down. I reported that the contacts are quite good, but better be safe than sorry even though this runs at a lower current.
OF course highly accurate tail readings is one thing, OTF lumens, OTF lux (throw), light drop due to heatsinking, total runtime on various batteries is another matter. It drops 2.2% in light intensity for 3 minutes in high, from 0:05 to 3:00. Full details in another thread which i posted.
This is new : I noticed that it did not low voltage cut, just dropped out of high/regulation and let it run slightly dimmer. This plus the slightly lower 2A drive might be interesting for some. All in all, the TF, SR, DRY and TK70 all cater for various needs. 
I've just did a quick comparison against my Fenix TK35 and I can say I'm quite pleased so far. The hot spot and spill is huge! The TK 35 has a little better throw with a smaller hot spot and spill. Color tint is cooler than the TK35 which I'm liking a lot.
Update: I measured the temperature with a Fluke model 62 Mini IR Thermometer after 17 minutes of operation. Both the Trustfire and Fenix were pretty hot. The Trustfire was slightly hotter at 52.4 degrees celsius measured at the head, and 50.2 measured midpoint at the battery compartment. The Fenix was 50.8 ant the head, and 48.8 midpoint at the battery compartment.
I wonder how safe those temps are for long term reliability and how much negative affect will those temps be on the batteries?
Hi guys, sorry for the semi-offtopic
Talking about multicell configurations
If you have a flashlight with 2 cells, and you measure the current at tailcap and you get 2Amp... what means? that EACH cell is giving 2Amps to the driver or that BOTH cells give 1Amps, so 1A + 1A = 2A?
Thanks
Current is like flow, same flow through everything unless you split it up (like parallel battery config). Voltage is like the height for the pipe that the current is flowing through. Each battery increase that level/height, increasing the pressure for the flow, generally speaking. Both can add up, but the way they do so is slightly nuanced. For example, if you measure 1A through each of two pipes in parallel and they flow into another pipe, you have 2A in the latter. However, not the case in series config.
i have not had a good chance to fully test it yet but just in the back yard the TR-3T6 puts out massive spill, ive tested 2 diffrent brands of batteries 4 of one kind 10 of another and i know the light is regulated but the difference in the cells and there internal resistance I'm getting from 2.6 to 2.9 amp draw over 2 x 18650,s, I'm really impressed with the trustfire flames for bang for buck.
Sorry because English is not my natal language and maybe I have not understood well.
If I have understood, for example, the TrustFire 3t6, with 2 cell in series, when measuring current at tailcap and the result is 2Amps, it means that EACH cell is giving 2Amps? Or viceversa (both cells give 1Amp and the final result is 2Amps)
Sorry...
Hi, just google series and parallel circuits in google/wikipedia. Lots of info + diagrams.
Yes, just as it doesn't matter where in the pipe you place a flowmeter, it will result in the same measurement.
OK, thank you!
my daughter was bugging me for a bush walk and wanted to see some kangaroo,s so we took the TR-3T6 and the Tr-1200 out for a walk just over 30 Min's.
we ran them both on high the whole time, the TR-3T6 is great for bush walking as the spill is decent, the TR-1200 out throws the TR-3T6 and at approx 80 meters the TR-3T6 will light up a talk bushy tree completely and the TR-1200 will light up most of the center of it and I'm talking about a decent size tree.
the TR-3T6 host got warm, a bit warmer then the TR-1200 but not hot and after being on high for a tad over 30 Min's the current draw on the TR-3T6 was 2.89 amps i could not be bothered going down to the shed and getting my temp gun out to see exactly how hot the screw in was as it would of cooled down to much.
after sitting for about 2 Min's i unscrewed it and could hold it in my hand as it was not that hot pritty much cold and had cooled off, I'm confident i could run it longer then that and when I'm not so buggered from work ill take it on some longer bush walks.
there is two models of the TR-3T6 and i got the 3 x 18650 model, there is a 2 x 18650 only, but i got the one you can run 2 or 3 18650,s on.
it seams your talking about the sky ray
any way for a tad over 30 Min's on high the current draw on the TR-3T6 was 2.89 amps on trust fire flames
so its looks like the driver is not the same as the sky ray 3800.
the TR-3T6 3 x 18650 seam,s to have a higher draw then the TR-3T6 2 x 18650,s from what ive seen on the net... and its the only one out of the two with a claimed 3 amp draw.