john stone wrote:

Have a 10Watt, 12Volt Hologen lamp for a christmas decoration. But the
mains tranformer I have is only 6 Volts.

Apart from being a bit dimmer, would there be any other consequences running
at the lower voltage? Thanks.

A halogen lamp on the correct voltage runs the filament hotter than a
standard incandescent tungsten lamp. Without the halogen gas filling,
this would soon cause the tungsten to migrate from the filament to the
inside of the bulb, where it would blacken the glass. The filament
would rapidly become thin and then would break.

At a certain temperature, the halogen will combine with the tungsten on
the inside of the glass. It then floats around until it meets the hot
filament, where it deposits the tungsten back where it came from
(approximately). This depends on having the glass hot enough to allow
the halogen and tungsten to combine, which occurs at near dull-red heat
(which is why quartz glass is necessary).

If you under-run the lamp, the filament will not blacken the glass as
quickly, but the glass will not reach recycling temperature, so any
blackening will remain. The relative temperatures of the filament and
glass will determine whether the life if the lamp is extended or
shortened. The light output will be very muchreduced and lacking the
blue end of the spectrum.

--
~ Adrian Tuddenham ~
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