Do you like PWM (pulse width modulation) controlled lights?

[Bright+]

Multiple output is a nice feature, but I'd prefer it the regulation was done before LED and I hate PWM.

PWM is ok for incans and motors since they have an inertia to ride through, but when it's used on LEDs, the resulting light flickers worse than old school fluorescent lights (which operates at 100 or 120Hz, because line cycle consists of a negative and a positive cycle and the lamps light up on both waves). Sinewaves don't spend much time at zero unlike PWM pulses that spend all of non-on time at zero.

As perceived by my eyes, flickering is even more noticeable at lower on-duration (duty cycle) even with a frequency around 150-400Hz, which seems to be a common range for many flashlights.

The phosphor in fluorescent lamps have a longer persistence than LEDs, so the effect isn't too bad. Flickering is noticeably worse on LED powered Christmas lights and such. HIDs are not nearly as bad as LEDs either as the capsule burns orange hot from heat which provides some light even during zero crossing to cushion visible flickering

 

[Serial Chiller]

My ITP C8 shifts between 6 and 190 Lumen and I can't notice any flickering. However, with most car rear lights it's much worse and really annoying. So my answer would be: "Like it, if it's done right".

 

[McAllan]

Yes it really depends.

I have a DX light (MTE C3-1 in stainless steel) which uses a very high frequency PWM. It's great. Haven't got any possibility to measure the frequency but it's quite high like a couple of kHz or something like that.

Then there's the opposite side with lights such as the "new" mini Mag Lite. It's without discussion too low in frequency. Some of my other DX lights are quite low too but hey I don't expect as much from them as I do from a big company like MagLite. Even for a Joe Average that PWM must the on the edge of unbearable - only reason not to complain/mention if would be if he didn't knew it could be done much better. No major technical change - just up the PWM frequency and it'd be very nice.

And then there's the AA Fenixes which don't use PWM. It's great too but they change color quite a bit on the lower modes.
So having a hard time to decide. Don't know if I love PWM or CC but I'm quite fine with either as long is it's properly implemented and not like some monkey brain made it.

 

[ky70]

Ive never seen PMW with my naked eye. I have a couple of lights that reportedly have this (ITP a3, qmini 123) but I have yet to visually notice PMW. The only time I've seen it was in a YouTube review (by Patriot) where the camera catches the PMW.

So at this point, ignorance is still bliss for me.

 

[the.Mtn.Man]

I don't mind it really. For me it's noticeable on the Mini Maglite Multimode but not enough to bother me. However, faster is definitely better when it comes to PWM.

 

[Flying Turtle]

It doesn't really bother me much, either. Of all my more recent lights I seem to notice it most in the Maratac AAA. Must be a particularly low frequency.

Geoff

 

[JaguarDave-in-Oz]

I have a couple of torches where I can see it on the lower mode but it doesn't really bother me and I think it's quite an ingenious way of managing the power levels.

 

[mn_doggie]

Isn't PWM the most efficient?

What other choices are there?

 

[UpChUcK]

Isn't PWM the most efficient?

What other choices are there?

Current controlled. And CC is more efficient.

I like PWM as long as the frequency is high enough to not notice the flicker in use. PWM does give a nice low low, which I love.

 

[Moonshadow]

I guess some people can see it more easily than others.

My ITP A3 is a really nice light but the PWM on medium and low is really annoying - a sort of 'school disco' strobe effect. Strangely, it seems much worse than the L0D even though the frequency is not any lower . . perhpas there are sharper edges on the square wave or something, but comparing the two side by side it is clearly worse.

The really really annoying thing about all this is that it's so easily avoided just by using a higher frequency like on the Preon. As SC says, it's OK if done right.

 

[Henk_Lu]

While I know what PWM is and that many people complain about some lights, I can't discern any flickering in normal use on the same lights.

So, up to this point I don't care about it as for flickering. I have loights however, which tend to a greenish tint on low modes and this is supposed as well to come from PWM, while I'm not sure about that theory of course. I surely don't like that and IIRC, current-modulation tends to a blueish tint, which would be nicer.

Complicated all that stuff!

 

[mn_doggie]

Current controlled. And CC is more efficient.

I like PWM as long as the frequency is high enough to not notice the flicker in use. PWM does give a nice low low, which I love.

Does current controll use linear type regulator? Is there some type of series current controlling device (like a bypass transistor in the old days of voltage/current regulators)?

I guess I'm not familiar with the types of current controlling devices used in flashlights. I've worked with PWM a bit over the years.

Just did a search. I see how the current control is done.

 

[Ragiska]

Current controlled. And CC is more efficient.

I like PWM as long as the frequency is high enough to not notice the flicker in use. PWM does give a nice low low, which I love.

only half true. above 20-30mA drive current CC is more efficient FOR THE LED, but PWM is (typically) more efficient FOR THE CIRCUIT.

 

[John_Galt]

I only dislike it when it is very noticeable.

Noticeable PWM is probably why I don't use myQuark AA, or Princeton tec Fuel. PWM on the lower modews of both give me a headache...

 

[KarstGhost]

On some lights that reportedly use it I don't notice it, but on the ones I do notice it bothers me a lot. It can be nausea inducing (literally) if you're using it up close for a lengthy amount of time. I'll continue to live with it if it provides low lows.

 

[SoCalMan]

I never noticed it on my Quark MiNi.

 

[mn_doggie]

only half true. above 20-30mA drive current CC is more efficient FOR THE LED, but PWM is (typically) more efficient FOR THE CIRCUIT.

By "FOR THE CIRCUIT" do you mean it is more efficient on the energy source or on component count?

 

[Zendude]

I like it as long as the freq. is high enough.

One advantage is it minimizes tint shift from high to low. The trade off being less runtime(from what I've read).

 

[SFfanman]

Has there been any tests or studies on the effects PWM has on the eyes and brain for both short and longterm? Also, is there any correlation between eye twitches, hypetertension, or other scientific based syndromes or diseases and noticeable or non-noticeable PWM? Or even more simply, has anyone ever had physical side effects from viewing a subject being lit with a light with PWM? :thinking:

 

[Zendude]

I only dislike it when it is very noticeable.

Noticeable PWM is probably why I don't use myQuark AA, or Princeton tec Fuel. PWM on the lower modews of both give me a headache...

Did you mean the Quark mini AA? Regular Quarks are current controlled. You must really be sensitive to PWM as the frequency of the mini is very high.