I recently purchased a N-Light ST50 XM-L NW version and when clicking the rather stiff forward clickie to change modes, the light would emit a really bright flash when changing modes from HI to LO. I emailed the seller and he says that N-Light confirms that its “normal” due to the design of their driver. The seller is happy for me to return the light for a refund.
Here comes the best part, being a CPF/BLF member, I guess I do not like to be taken for a ride. So here I am posting this question to the owners and experts of LED flashlights: Is it normal for multimode XM-L drivers to exhibit a bright flash when changing modes from HI to LO?
If not, does this sound like a manufacturing/design fault to you? I have googled this issue and found nothing that would explain this bright flashing to be “normal”.
On some drivers the bright flash on low signifies mode changes - leave alone, it stays as is, turn off within a couple of seconds you can change the mode group (strobes ramping etc). I don’t know about the n-lights, but I do have drivers that do this (ld 25 springs to mind).
I have the old version ST50 that has 5 modes: L-M-H-Strobe-SOS (Head twist Turbo), so I'm not going to be much help as you no doubt have the new H-L version. There is no bright flash between any modes on mine, however.
I have a few drivers that do that. The P60 drop-in from IO is one. When changing modes, it briefly comes on in the previous mode. It is not very noticeable when changing H-M, but appears as a bright flash when changing M-L.
I have two of the IOS P60 dropins (3A T6-3C) and neither displays a bright flash when changing modes. Maybe I am getting old and my eyes just don’t catch it but I don’t think the IOS dropins are suppose to flash during mode changes.
Sorry to derail OP’s thread, but my IOS drop-in is the 3 mode 2.5A neutral. It flashes between medium and low. I’m sure you’d notice if yours was affected. It was discussed here
Thanks for the straight forward answer guys! I’m quite indifferent to it really, as long as it doesn’t burn out the driver and/or LED before I turn 80!
I don’t believe it will cause any harm. It appears that it is a function of the mode memory logic. Those drivers turn on at the previous mode before they check the timing to determine if the mode should change.
I have Jakes version and i dont get any preflash……mine is super low, high, and then turbo with the twist of the head. If i may ask what batts are you using.
I have seen this behavior when playing with UI programming. I would say it is a software problem with the driver. If the driver has active polling of the switch (i.e. pin goes high/low) then it would be a benefit to disable the PWM module when it goes low. Only re-enable when Mode change is made, and switch goes high again. That is how I got rid of the annoying bright flash problem.
As you can see from the video, there is a brief flash when changing modes from HI to LO. Take a close look at the reflections against the black flashlight holster just above hotspot to get a better view of the flash just before it comes on LO.
I've not followed this thread, I've just seen the video. Sor of reminds me of the $4Sevens moonlight on some specimens, when you were turning them on moonlight a full burst of light would briefly come on first.
One thing I noticed in your video and another video is that the ST50 has some PWM that that cameras can pick up. I have to say that mine (almost 1 year old now) does not have any visible PWM on any mode what soever, nor any fan or camera can pick it up. So it looks like they use a different driver now.
Yup, as per allan d. explanation and my fix……… driver software should check mode change before re-enable PWM. Simple as that, we are only talking micro seconds here. There is absolutely no reason I can see why the consumer should suffer.