Hmm, so what makes leds have an issue with higher frequencies then, I'd have
thought this was of no concequence , but maybe its to do with the individual
colours of led in the package having different levels on higher
frequencies.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Arfa Daily" wrote in message
...


"Colin Stamp" wrote in message
o.uk...
Hi all,

I tried out some Ikea LED candle bulbs today, wondering if 90 lumens
would be enough:-

http://www.ikea.com/gb/en/catalog/products/30217927/

I thought I was impressed. 90 lumens turned out to be a little bit on
the dim side, but they look quite reasonable in the fittings, which were
intended for halogen candles. The light comes out in about the right
places IYSWIM, The colour is fine and they're cheap.

Then came the realization. The sodding things strobe really badly. Now
I've noticed it, I can't get away from it. Anything that moves in the
room turns into bloody set of freeze-frames, as does the whole room
every time you move your eyes!

Is this a common thing with cheap LED bulbs? I'm all worried about the
impending Ebay purchase of Chinese replacements now. The only other LED
bulbs I've got are two brands of GU10 and they're fine, so maybe it's
just Ikea ones that are crap...

Cheers,

Colin.


The way to get the maximum brightness and longest life from LEDs, is to
pulse drive them. They're actually not very good at handling high
frequencies, so they tend to get driven at fairly low pulse rates, and
that's why you see the strobing. It's been driving me mad for years with
LED car tail lights where the situation is even worse because they use the
fact that they are pulse driving them, to open up the mark-space ratio to
something like 50% when they are a tail light. This gives the impression
of half brightness. When the car owner treads on the brakes, the pulse
drive tightens right up to give high brightness, but the strobe effect
becomes less noticeable. Those lights that they stick on the top of
traffic cones are also LED based, and also strobe for the same reason.
Possibly, the better quality LED lamps like your GU10s, use better quality
LEDs that can be driven at a higher pulse rate, or maybe, they are DC
driving them ?

Arfa