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[Marks DTM Calib]

If I shook my head it was very obvious. was basically a couple of columns and appeared like this.

:: :: ::
:: :: ::
:: :: ::

Not viewing angle, but driving frequency.

They should be driven so that there are some lit all of the time.

Thats likely to be more down to some sort of defraction grating in the lense setup.

Certainly jack all to do with the switching frequence.....if thats above 30Hz you wont notice it.....at 100Hz plus its certainly not the issue.

No it was the swith frequency imagine that each dot was a diode and normally two columns, move your head and you got the extra columns as they pulsed on and off

Again, sounds more like a grating.....if it was switching frequency then it would have nothing to do with the position of your head  

[Martin_1962]

If I shook my head it was very obvious. was basically a couple of columns and appeared like this.

:: :: ::
:: :: ::
:: :: ::

Not viewing angle, but driving frequency.

They should be driven so that there are some lit all of the time.

Thats likely to be more down to some sort of defraction grating in the lense setup.

Certainly jack all to do with the switching frequence.....if thats above 30Hz you wont notice it.....at 100Hz plus its certainly not the issue.

No it was the swith frequency imagine that each dot was a diode and normally two columns, move your head and you got the extra columns as they pulsed on and off

Again, sounds more like a grating.....if it was switching frequency then it would have nothing to do with the position of your head  

Moving eyes rapidly - good way of finding flickering lights

[Marks DTM Calib]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

[Martin_1962]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

Fluorescent only when nearly worn out (one near me right now) and never with a filament bulb.

But does the fluorescent coating have latency so it never goes dark?

[Marks DTM Calib]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

Fluorescent only when nearly worn out (one near me right now) and never with a filament bulb.

But does the fluorescent coating have latency so it never goes dark?

It has a level of latency but, the graph is a log setup so the high brightness decays very fast leaving a background lvel of light over the period of a minute......and hence why Plasma and CRT Tv's can not display true black.

Bottom line is, the effect still sound more like that of some sort of grating (which is often used in such lenses to difract the light) resulting in many bright and dark spots.

I cant beleave they use a switching frequency as low os 30 Hz.....1Khz minimum I would of thought these days.

[Kevin Wood]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

They have quite short "off" times in comparison, though. An incandescent bulb has a filament that filters out the mains frequency by virtue of the fact that it has heat capacity and both types will conduct on both halves of the 50Hz cycle.

As it happens I have a 'kin bright LED cluster on the bench at the moment that is destined for the rollbar of my Westfield so I might have a little experiment and see if I can reproduce the issue, because these lights get to me too. I'm sure it's some sort of multiplexing / PWM issue, although I can't understand why they'd be switched so slow.

Kevin

[SheWhoMustNotBeOUTBID]

[smiley=undecided.gif] I started reading this thread thinking that you had one on your Omega & it was that one that was causing you a headache!  

I would have thought it would be the HID headlamps from Jags, BMWs & Mercedes that would have caused a headache.

How long was spent behind this uber bright rear Led brake light?

Never look into the light.....  [smiley=laugh.gif]

No.., contrary to advice offered at the beginning of the thread.., don't close your eyes as u may find yourself GOING 'into the light' very shortly afterwards

[Marks DTM Calib]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

They have quite short "off" times in comparison, though. An incandescent bulb has a filament that filters out the mains frequency by virtue of the fact that it has heat capacity and both types will conduct on both halves of the 50Hz cycle.

As it happens I have a 'kin bright LED cluster on the bench at the moment that is destined for the rollbar of my Westfield so I might have a little experiment and see if I can reproduce the issue, because these lights get to me too. I'm sure it's some sort of multiplexing / PWM issue, although I can't understand why they'd be switched so slow.

Kevin

Again, you would be surprised how much the temp of the filament changes as the cycle moves and hence the light does indeed flicker.

[Marks DTM Calib]

Put it this way......do you notice flourescent lights flickering and incandescent lamps flickering?

They have quite short "off" times in comparison, though. An incandescent bulb has a filament that filters out the mains frequency by virtue of the fact that it has heat capacity and both types will conduct on both halves of the 50Hz cycle.

As it happens I have a 'kin bright LED cluster on the bench at the moment that is destined for the rollbar of my Westfield so I might have a little experiment and see if I can reproduce the issue, because these lights get to me too. I'm sure it's some sort of multiplexing / PWM issue, although I can't understand why they'd be switched so slow.

Kevin

Again, you would be surprised how much the temp of the filament changes as the cycle moves and hence the light does indeed flicker.

As a way to observe this, put a diode in series and chop out half the cycle.....this makes it very obvious.

The only reason I can think they are using any sort of switching on an LED light is to maintain a constant brightness at varying supply voltages....and every LED driver IC I have seen in past years has had swicthing frequences of 20Khz upto 2M

[Martin_1962]

I think it may have been faulty - don't often notice issues like this.

Definately visible flickering

[Kevin Wood]

As a way to observe this, put a diode in series and chop out half the cycle.....this makes it very obvious.

The only reason I can think they are using any sort of switching on an LED light is to maintain a constant brightness at varying supply voltages....and every LED driver IC I have seen in past years has had swicthing frequences of 20Khz upto 2M

Agreed. LEDs would need some control especially if they're driven hard.

There's no sensible reason for the flickering, but I have observed the same issue. I guess it could be a fault condition where the current (for example) exceeds some protection threshold and the device shuts down only to restart a few tens of milliseconds later. :-/

Maybe a single LED failure in a larger array would cause something like this?

Kevin

[Jimbob]

I have used LED sidelights which flicker like hell just before failure

[LJay]

I suffer from migraine and have been known to pull over to avoid having to look at flickering lights.
Didn't think much of it though, just assumed they were faulty.