Question on Quark Tactical and PWM

[rookiedaddy]

According to 4Sevens design philosophy:
"4. Buck/Boost Driver
Efficiency is paramount in our circuits. 6 out of 8 models will have buck/boost circuits, and the remaining two have buck. Full regulation, no PWM. And true low lows."

I recently notice that both my Quark 123² Tactical Neutral and both my Quark 123² Turbo has noticeable PWM on low and medium mode...

- is this normal?
- does the above design philosophy NOT apply to tactical model?
- are my tactical Quark model the exception?

I've check my other Quark AA² regular and there are no noticeable PWM on all modes.

Greatly appreciate if anyone can confirm this? or direct to an existing discussion... (didn't find any discussion on this after search :shrug TIA.

 

[Ragiska]

there is no PWM. just look at the occiliscope traces in the MP.

 

[Rod911]

I found this video that was posted by Patriot in this thread which provides a great way to visualise the PWM.

Using said method, I tried it on a Preon Ti I, Catapult and Quark AA² Tactical. The latter two produced a straight 'line' with no breaks in between in all modes from its lowest to its highest. Whereas the Preon had distinctive breaks in its line in low and medium modes. Having said that, I could not detect the PWM with the naked eye.

 

[cave dave]

A number of people have reported visible PWM for the 6v head models.

My Ti 2xCr123 tactical model has visible PWM on Low and Med, using 2xCR123s or 1x18650. I can not see PWM on moon, high or max.

My eyes are pretty sensitive to PWM, I can easily see even the very fast PWM on the Preons and the MiNi series as well.

 

[JaguarDave-in-Oz]

I recently notice that both my Quark 123² Tactical Neutral and both my Quark 123² Turbo has noticeable PWM on low and medium mode...

- is this normal?

I have no technical knowledge of why but I have four Quarks and wiht two ot three of them if I shine them on my hand on the lowest setting I can see the light "vibrating". It's very obvious up close and very repeatable.

 

[Beamhead]

As Cave dave mentioned it must be the 6-9v heads only, I verified that my 2x123 model has PWM via Patriot's camera trick, my 1xaa nor my 2 1x123 models have it.

 

[Ragiska]

there is absolutely NO PWM.

http://www.cpfmarketplace.com/mp/showpost.php?p=2320812&postcount=12

In moon mode, it is actually driving the LED at 1ma which is very very low.
The MCU has to control this kind of current to the emitter very finely.
There are small ripples from the regulation which actually exist in all constant current drivers.
Perhaps, due to the low driver current, this fluctuation becomes more observable. 0.1ma variations in a 1ma drive current shows up more than
a 0.1ma variation at 700ma.

 

[Beamhead]

there is absolutely NO PWM.

http://www.cpfmarketplace.com/mp/showpost.php?p=2320812&postcount=12

From your link......."That is wrong information. Moon and low are NOT controlled by PWM. I know the circuit. These are wrong assumptions."......

I checked on medium the first time and just now checked moon and low, moon and low had no PWM via the camera, but medium did again.
Is the camera trick a reliable way to verify? :thinking:

 

[AnAppleSnail]

There "should be" no PWM. But if you see it (or some other flickery mess), try contacting 4sevens about it? I'm sorry that there's problems with the light.

Edited: Even if it's not really PWM control, it could be flickery.

 

[Ragiska]

did anyone even read the explanation? it's NOT pwm, but a regulation dither, which is NOT the same thing.

 

[Beamhead]

did anyone even read the explanation? it's NOT pwm, but a regulation dither, which is NOT the same thing.

Yes, I read it and he was addressing the preflash on low and I quoted that he said that moon and low are not PWM, did he state that for medium?

 

[4sevens]

did anyone even read the explanation? it's NOT pwm, but a regulation dither, which is NOT the same thing.

The Quarks (excluding the mini's) do not use PWM to regulate the light. However due to the super low levels of output, some unit may exhibit "pulses" or "regulation dither" but it is not pulse width modulation.

All regulation, whether buck, boost, or buck and boost uses a cycle of charging and discharging an inductor and capacitor to step up or down and when you are driving LED at low levels as we are, sometimes you will get slightly visible pulsing. Even if you can't see it, an o-scope hooked up to the LED will see it. This is normal and nothing to be worried about.

 

[Ragiska]

Yes, I read it and he was addressing the preflash on low and I quoted that he said that moon and low are not PWM, did he state that for medium?

read the post in context. people at the time were claiming the quark line's low drive currents on moon and low, since they were below the magic ~20mA peak efficiency point for high flux led's, HAD to use PWM. 47's was correcting them that ALL modes on the quarks (at the time, mini's were not out) were constant current with NO pwm, but the circuitry did have a small regulation dither artifact.

 

[rookiedaddy]

I found this video that was posted by Patriot in this thread which provides a great way to visualise the PWM.

thanks for the link, I've tried it on mine and I can see the dotted line in my camera.

A number of people have reported visible PWM for the 6v head models.
My Ti 2xCr123 tactical model has visible PWM on Low and Med, using 2xCR123s or 1x18650. I can not see PWM on moon, high or max.

thanks for confirmation, good to know I'm not alone.

As Cave dave mentioned it must be the 6-9v heads only, I verified that my 2x123 model has PWM via Patriot's camera trick, my 1xaa nor my 2 1x123 models have it.

yaa... that could be it, more visible on the 123² heads.

there is absolutely NO PWM.
http://www.cpfmarketplace.com/mp/showpost.php?p=2320812&postcount=12

thanks for the link and correction.

The Quarks (excluding the mini's) do not use PWM to regulate the light. However due to the super low levels of output, some unit may exhibit "pulses" or "regulation dither" but it is not pulse width modulation.

All regulation, whether buck, boost, or buck and boost uses a cycle of charging and discharging an inductor and capacitor to step up or down and when you are driving LED at low levels as we are, sometimes you will get slightly visible pulsing. Even if you can't see it, an o-scope hooked up to the LED will see it. This is normal and nothing to be worried about.

ahhh... thanks 4sevens. :thumbsup: need to read-up more.

 

[Beamhead]

Thanks for clearing this up 47, so the camera method for PWM is not 100% because it also pics up regulation dither.

 

[cave dave]

So it may not technically be "PWM" but it is just as annoying as PWM if you are annoyed by such things as I am. I think not calling it PWM is just a technicality.

I would guess the strobe effect on my 2xCr123 tactical is at about the 200hz frequency. Its pretty darn noticeable on the 4 lm and 22lm setting, and un-noticible on the other settings. I find it a bit headache inducing so I find these two setting virtually unusable.

 

[cave dave]

It may not technically be "PWM" but a duty cycle that pulses the output from 100% to 30% power approx 200 times a second is visible to a lot of users (although not everybody). I am so sensitive that I can now actually estimate the frequency of the PWM with my bare eyes. I guessed the strobe effect on my 2xCr123 tactical at about the 200hz frequency in the above post, before I even saw the graph that was linked above and I quoted below.

Originally Posted by HKJ (View Post)
It is not pwm, but artifacts from the regulation, on a scope it look like this:

low:

I think maybe real PWM has a duty cycle from 100% power to 0% power, and looks more like a square wave.

... This is normal and nothing to be worried about.

It is when you are the 1 in 10 users that are annoyed by PWM.

On the topic of PWM. So far I am the only person that I know of that has reported they can clearly see the PWM (~2300 hz?) on the Preon and the Mini. I find it somewhat noticeable but the very fast PWM isn't really annoying. I do find the ~ 900 hz PWM on the IlluminaTi annoying though.

EDIT: Note: Only my 2xCR123 Tactical has the visible "PWM like phenomenon", the two 0.9v-4.2v heads I have (tactical and regular) do not exhibit this "PWM like" phenomenon with any combo of batteries I've tried. (1AA, 2AA, or single LiIon)

 

[4sevens]

cave dave - also PWM jumps between 0% and 100%.

If you're that bothered, I'd be interested to see if yours is "warbling" within normal range. I don't mind checking it out and letting you know - if it is out of bounds I'll be glad to swap it for you. (I suggest this at my own peril - watch my PM box get jammed with messages!)

 

[csshih]

this is from a preon II on low

and this is from a tactical quark 123^2 on medium

see the jumps from the PWM as opposed to the CC?

 

[4sevens]

^ thanks craig. but note 1) different time division 2) preon II is 3v while q123-2 is 6v