On Mon, 23 Jan 2017 13:11:46 +0000, Martin Brown
wrote:

On 21/01/2017 18:16, Scott wrote:
On Sat, 21 Jan 2017 18:03:03 +0000, Lee
wrote:

On 21/01/2017 17:56, Lee wrote:
On 20/01/2017 14:41, Brian Gaff wrote:
Have you also checked to see what interference they can chuck out.
some are
terrible, one assumes the dreaded switch mode psu.
Brian

Most of the more recent ones seem to be capacitive dropper...

^^^^ "some" not "most"

As a matter of interest, why to the 12 Volt ones seem to be more
problematic than the mains ones?

The 12v ones tend to be powered by a toroidal transformer expecting to
drive a lot more current into the original quartz halogen lamp fittings.

That is the position with mine. I was told (rightly or wrongly) that
there is no minimum load for a toroidal transformer. You seem to be
suggesting that the voltage can increase, but I thought these lamps
could cope with up to 24 volts anyway.

Halogen lamps require a substantial current and run mad hot so the
fittings are designed to insulate the ceiling from the very hot lamp.

In my case the lamps are on a track so I don't think they are
particularly thermally insulated. There is plenty of air surrounding.

This is almost a perfect storm for an LED bulb PSU. No way to convect
away hot air and a PSU that is over voltage due to an out of spec load.
They should be able to cope with the higher voltage within reason but
they cannot cope with having a running temperature much above 95C
without significantly shortening their lifetime.

Does this cause RF interference or simply a problem with lifespan?

Think I'll go back to halogen lamps and make energy savings in some
other way (or maybe plant a tree as carbon offset). .