🚀 go-pugleaf

johnh@macadam.mpce.mq.edu.au (John Haddy) writes:

>In article <27806@castle.ed.ac.uk>, cam@castle.ed.ac.uk (Chris Malcolm) writes:
>|> I have read that running halogen lamps on reduced voltage will shorten
>|> their life, the argument being that their life depends on a cycle of
>|> tungsten sublimation and redeposition which requires a certain
>|> temperature to work. However, it seems to me that at lower
>|> temperatures where it doesn't work (so well) it is not needed, i.e.,
>|> tungsten/halogens should have the same kind of life/voltage graph as
>|> ordinary vacuum tungstens.
>|> Can someone who knows confirm or deny this?

>I have a catalogue which states that a halogen lamp's life is DOUBLED if run at
>5% under voltage; and HALVED if run at 5% over.
>The down side is that light output drops by 17% for a 5% undervoltage lamp.
>These figures are for 12V tungsten halogen lamps - the ones with the inbuilt
>dichroic reflector.

>A thought:
>	There's been a lot of hoo-ha recently about the high UV content of the
>light output of these globes, due to the high operating temperatures. Does
>anybody know how much the spectrum will differ if the globe is run 5%
>undervoltage? I can't be bothered doing my own black-body radiation calculations
>(its a bit difficult when you don't have all the data :-)

On the subject of halogen and such headlamps, I can remember reading
in a publication directed at Automobiles, an article about the new
headlight's that Volvo(?) were putting out with their new range of
cars....  From memory it was a DI (Sorry, I might be an EE, but this
lost me) lamp in place of the standard QI type lamp...  the idea being
increase of intensity in some part of the UV region, supposedly
allowing an increase in the light penetrating the fog/mist, giving a
higher visibility....

Anyway, I have no idea of the point to what I just typed, but if
anyone knows any info on the 'DI" lamps, I would be interested to hear
the principles behind them...

Damien/IronEagle

>JohnH

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