My new Fenix LD12 gen2 has PWM

[Mr Floppy]

What does PWM stand for!? Jesus christ!

I believe that fenix lighting is a US distributor that associates closely with Fenix, plus you probably got a customer service drone who would not be so technically adept. You probably needed to say the light flickers very fast or something at that level.

 

[MojaveMoon07]

My only experience with PWM is with a Fenix L0D Rebel 100. While shining it on something within a few feet of my eyes (e.g., turning the page of a book), I would feel a sudden twinge of nausea.

While no one is yet reporting seeing PWM in the LD12 xpg2 during normal use, maybe a model of flashlight like this is usually used for tasks that are more than a few feet away. Has anyone used this model often enough at a distance of six feet or less that has yet to experience any PWM-related nausea ?

 

[sackless]

I believe that fenix lighting is a US distributor that associates closely with Fenix, plus you probably got a customer service drone who would not be so technically adept. You probably needed to say the light flickers very fast or something at that level.

It's a bit like phoning up your car insurance and getting through to someone who doesn't know where the exhaust pipe is...

 

[raptechnician]

so glad I never ended up buying any Fenix lights...

 

[sackless]

so glad I never ended up buying any Fenix lights...

In all fairness though, Fenix used to be great. Their lights were great value, high performance and well designed but now they're a bit... crap.

EDIT:
I just checked my email to find that Fenixlight have sent me a 'proper' reply. Unfortunately, Fenix deny that the LD12 uses PWM. In their words:

"I have consulted our electric engineer. He explained that as below:
​

​

Test the light by phone or camera isn't reliable, because the test equipment has its own frequency also. We use Oscilloscope and integrating sphere to test the beam of the flashlight. That can avoid the extra interference.​

​

The LD12 is constant current circuit, not PWM."

<sarcasm>Well that's totally restored my faith in them</sarcasm>
​

 

[derfyled]

My only experience with PWM is with a Fenix L0D Rebel 100. While shining it on something within a few feet of my eyes (e.g., turning the page of a book), I would feel a sudden twinge of nausea.

While no one is yet reporting seeing PWM in the LD12 xpg2 during normal use, maybe a model of flashlight like this is usually used for tasks that are more than a few feet away. Has anyone used this model often enough at a distance of six feet or less that has yet to experience any PWM-related nausea ?

In my case, distance don't change anything. I see PWM everywhere. Cheap cellphone screen, cheap laptop screen, car lights, alarm clock, electronic road signs, etc. The nausea you are describing happens as soon as I shine something, even far, and i turn my head. So the LD12 will never be in my collection.

Even 4/7's Mini that are supposed to have undetectable PWM is very perceptible for me.

 

[regulation]

In all fairness though, Fenix used to be great. Their lights were great value, high performance and well designed but now they're a bit... crap.

EDIT:
I just checked my email to find that Fenixlight have sent me a 'proper' reply. Unfortunately, Fenix deny that the LD12 uses PWM. In their words:

"I have consulted our electric engineer. He explained that as below:
​

​

Test the light by phone or camera isn't reliable, because the test equipment has its own frequency also. We use Oscilloscope and integrating sphere to test the beam of the flashlight. That can avoid the extra interference.​

The LD12 is constant current circuit, not PWM."

<sarcasm>Well that's totally restored my faith in them</sarcasm>
​

Anyway, glad to know that the puzzle was clear now.

 

[Mr Floppy]

I just checked my email to find that Fenixlight have sent me a 'proper' reply. Unfortunately, Fenix deny that the LD12 uses PWM. In their words:

In all fairness, it isn't supposed to have PWM, and it's good to have that clarified by the engineer. So what you are seeing is a bug then, given that it goes away when you switch the light off and on. Hopefully they can see that now and review the circuit in that light.

 

[pzmobile]

There is also a post about LD12 PWM on a Chinese flashlight forum. And the customer service from Fenix replied as follows.
I don't know if I can translate it well.

--------------------------------start-----------------------------------
The circuit design of LD12 is to keep current stable (output stable) under a certain voltage range. Here are the fig.s of voltage on LD12 LED. (input: 1.5V . Oscilloscope settings: DC 10X and AC 10X)



low output ,DC ripple

low output, AC ripple

turbo mode, DC ripple

turbo mode, AC ripple

DC ripple of low output is flat. There is about 100mv ripple when turn on turbo mode.
AC ripple of low output is also flat. There is a peak-to-peak value of 34.9mV on turbo mode. Its frequency is 384KHz.

In summary, we believe that this circuit is a constant current circuit, instead of the PWM circuit.

----------------------END-----------------------------------------------------------



Again, I'm not professional on electronic nor English translation.:shrug:

and I don't know why AC is used here.

 

[Mr Floppy]

Compare it to the ripple from here:
http://www.candlepowerforums.com/vb...chart-(PWM-)&p=4290688&viewfull=1#post4290688
It looks like the ripple is much higher, although I don't understand the scales involved.

 

[hiuintahs]

......... and I don't know why AC is used here.

Those were the same plots that were sent to me by the way.

What is meant by "AC" here is that you can put your oscilloscope in DC mode or AC mode. By putting it in AC mode and then cranking up the volts/div, it shows more detail of the AC ripple because the waveform will now be in the center of the O-scope screen instead of referenced from ground (ie: 0v level).

The highest modes always have the most ripple because the current load is the hardest on the regulator circuit. I see it when I do a run time test. But to have extreme ripple (higher than turbo mode) on the lower modes tells me something is wrong. For the two LD12's that I tested, the 2nd mode from the top had more ripple than turbo and it was a big difference too.

These graphs that Fenix is sending out are the ideal designed intent. And so this makes me wonder if they have a manufacturing issue with a wrong part or value being installed that they are not aware of.

Though the affect is PWM, I would say that what we are dealing with here is a noisy regulated circuit.

 

[selfbuilt]

FYI, I've just posted a mini-review of the LD12 - with a thorough oscilloscope examination and discussion of the "flicker" issue.

Fenix LD12 (1xAA, XP-G2 R5) Mini-Review: RUNTIMES, OUTPUT MEASURES, VIDEO

:wave: