John Rumm wrote in message .. .
Zymurgy wrote:

Hmm, that's all well and good but how does the light look in real
terms. I have LV and 240 halogens installed, the LV is clear white,
the 240V have a yellow tinge and don't appear to throw out much light.

I think you are right - you get more light for a given wattage from the
LV. Also you may find that with modern LV transformers (i.e. ones which
are not transformers at all, but actually small switched mode power
supplies) they will be less affected by local voltage sags and brownouts
that can give the 240V cousins a yellow tinge.

What is this dichroic of which you speak. are these whiter ?

You can get dichroic bulbs in LV and 240V although they are more common
in LV. It just describes the way in which the reflector is designed. A
standard bulb will normally have a metal (aluminium) coated reflector
that reflects like a mirror - most of the frequencies of light (and
hence infra red/heat) produced by the hot filament get projected
forward. As a result you are stuck with the natural output spectrum of a
discharge lamp - which is not very daylight like - giving the yellower
light plus lots of heat.

The dichroic (literally "having two colours" or "two frequencies")
reflectors allow some "colours" to pass through the reflector while
reflecting others. This lets you "tune" or equalise the colour of the
projected light and at the same time loose some of the projected heat
(it is still generated but more is absorbed by the light fitting).
Hence you get a different quality of light from them - making them seem
more natural and whiter. They also tend to make for slightly more
"specular" illumination. Hence shiny things seem more reflective and
sparkly, which is why they are good for shop displays and spot
highlighting in buildings.

Excellent, thanks. Exactly what I wanted to know.

This ...

you are stuck with the natural output spectrum of a discharge lamp - which is not very daylight like - giving the yellower light plus lots of heat.

Is exactly what I have.

I'll try new bulbs, otherwise the fitting is coming down. Even with
200W kicking out in the kitchen it's still dull in there.

Cheers,

Paul.