On 27/02/2013 09:15, Brian Gaff wrote:
Well the issue of course is that they have no thermal persistence as most of
the filament bulbs do and presumably go out completely when zero is
crossed. I'd have thought in this day and age they would have been able to
sort this out electronically, though of course if they did use a switch mode
solution the crud put out in the RF area might be rather bad.

Brian


They are usually switch mode. The ones I've seen run at a few tens of
kHz, but there is still the 100Hz pulsing of the rectified mains supply
to contend with. If it isn't smoothed before driving the switcher, then
the switcher will die and restart every half-cycle. It only takes a
capacitor to bridge the gaps, but it seems Ikea saved some money...

Cheers,

Colin.