LED lights and flicker, what causes it, why does it stop?

27 Jan 2008
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Llanfair Caereinion, Nr Welshpool
United Kingdom
I fitted a 5 lamp G9 lamp in wife's bedroom, she insisted she wanted G9 and salesman said you can use LED, also wanted to switch from bed side so used an Energenie Mihome wifi light switch and remote control.

First problem was it would not switch off, so just managed to get a load capacitor to fit inside the ceiling rose of the fitting, however then she noted a flicker which was annoying, one LED failed so as a temporary measure I fitted one quartz tungsten bulb, all seemed to work great, so thought buy a box of quartz bulbs and continue using one tungsten bulb.

As expected the second hand tungsten did not last long, however the odd thing is now it had blown still no flicker.

I would assume flicker causes because the switch needs to use some power to work, but you can hear the relay click when turned on/off and with flicker relay was not heard, so switch is not switching on/off, and not a dimmer it is simple on/off.

So may be cause for flicker connected to bulb not the switch? but they were flicking before quartz bulb fitted, and did not flicker when quartz bulb fitted even after it had blown, so what causes the flicker?
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G9 LEDs are mostly a complete fail, as they are physically too small to fit components for power supply smoothing and similar inside, and their small size also increases the heat density, so they are far more likely to fail compared to other LED lamps.
Yes the G9 are dimmer-able, but not actually dimming them, it is just an on/off electronic switch without a neutral, and yes all the other switches with E14, BA22d, and GU10 have no problem, it is only the G9, as soon as I started this post saying it had stopped, it started again, I use one quartz G9 and then all seem to work OK. I now have a stock of G9 quartz as if they stop doing them it means changing the chandelier, which is not some thing I want to do as less than 1 year old.
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The light from the work lamp on my bench recently started to shimmer, at about 10 Hz. Perceived as shimmering shadows as if the filament was moving. Brightness appears to be constant

Using a lens to project an image of the filament onto a sheet of paper revealed that part of the filament was vibrating.

Quartz capsule, "U" shaped filament with the mid point ( bottom of the "U" ) held by a moulded glass support.

Both legs are very floppy

Only one side of the "U" was vibrating,

Filament is coiled wire, I wonder if the effect is magnetic interaction. Or convection motion of the gas in the capsule

This lamp is direct on mains but I wonder if in other lamps the vibrating filament and associated magnetic effects could affect the current flow enough to disturb the operation of dimmers and/or electronic switches,
It seems flicker is common as this list of bulbs with No flicker apparent on any tested bulb is published, so clearly there would not be a list of compatibility if it was not a common problem, it lists one G9 bulb, Philips master 2.3W however I can find Philips master as GU10 but not at G9, the other Philips bulbs are around £4 each so £20 for a set, and others do complain about flicker, and light is aimed up from bulb where all bulbs I use now aimed sidewards, having had problems with expensive Philips bulbs in the past with a very short life, not inclined to try Philips again.

Bottom of chart is says
light-compatibility-chart-web said:
Recommendations: We advise our customers to use Dimmable LED bulbs ONLY and a minimum of 5 Watts per bulb recommended. We recommend using the Lumilife bulbs (minimum of 3 with a dummy load).
Well I have a dummy load but the bulbs are not 5 watt, no other fitting uses a dummy load, and in dinning and living room the E14 bulbs were not dimmable, I understand 5 watt total, but why 5 watt per bulbs not a clue. I can get a pack of 5W bulbs for £9 however last lot not arrived yet, and 25W of LED lighting in a small bedroom is going a bit OTT.

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