# Any effects of AC mains flicker?



## eyeballpaul (Jun 17, 2011)

Hi all, today CFL's are criticized a lot for their 100/120hz flickering effect, caused by nature of alternating current. But looking at standard incandescent lamps through short exposure viewfinder, turns out that they strobe even more, and LED bulbs without proper pulse-flitering have almost 100% flicker cycle. So can i ask, is the 100/120hz strobing of any lamp can cause any long or short effects on human? I searched all over the internet, but found almost nothing, only some "dangers of cfl".

Thanks for any input.


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## 2xTrinity (Jun 18, 2011)

As far as I know, no modern CFLs drive the lamp at 60Hz. Those were mostly older linear tubes with the heavy iron transformer ballasts. Modern electronic ballasts on most linear tubes and CFLs rectify the 120VAC, then chop it up into a ~10kHz square wave. Because the tubes are driven with a square wave, rather than a sine, intensity is nearly 100% at all times anyway. An exception to this is T8 tubes that have PWM dimming ballasts turn on the lamp for only part of each cycle -- even then, 10kHz+ is too fast to see. 

I've looked at light intensity from the tubes with a fast photodetector, there is hardly any fluctuation at all, let alone visible flickering.


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## Ken_McE (Jun 19, 2011)

eyeballpaul said:


> LED bulbs without proper pulse-flitering have almost 100% flicker cycle.



This is one of the differences between well made bulbs and cheap Chinese junk.


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## SemiMan (Jun 28, 2011)

Chinese junk does not flicker either as they are all electronic ballast as well. This is just people living in the past making the same complaints they made 10-20 years ago when florescents used magnetic ballasts. That is the exception now, not the norm and for CFL unheard of. For LEDs, yes some cheap chinese junk, think 100's of 5mm LEDS will flicker, but I do not think anyone on this forum actually considers that a light.

Semiman


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## mr.gukong (Aug 25, 2011)

No effects...






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## xul (Aug 28, 2011)

If a diligent search turned up no results, any health effects are probably "subclinical" but cell damage on a molecular level may take 20 years to show up.


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## SemiMan (Sep 14, 2011)

As a guess ... and only a guess, there will be infinitely greater health effects from either UV content and/or reduction in melatonin from blue.

Semiman


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