Re: Light

[Wright Huntley <jwwiii at pacbell_net>]

Metal Halide are gas discharge devices,where UV from a vapor discharge 
excites phosphors, much like fluorescents. The efficiency and spectrum 
depend on the phosphors used. Need a ballast to get high voltage and 
control the current flow. Mostly used at 100W and more. Most have an 
outer safety glass to block UV and protect against inner-glass 
explosion. That is, they are a globe inside a globe.

Halogen lamps are incandescent lamps (filament) that use a special gas 
mix and a tiny high-temp. ("quartz") envelope to allow higher filament 
current without burning out so fast. They are still inefficient, and 
produce more heat than light. The small bulb allows for a bit better 
reflector design. Emit too much UV for safety without a protective cover 
glass. The cover glass also prevents contact with the screamingly-hot 
bulb. Most are from 20W-300W. Many are low voltage and need a 
transformer to get 12V.

Wright


Morris, George wrote:
> Good morning ever5yone.  Not long ago someone said that there is a big
> difference between halogen and metal halide lamps.  At the time I didn't pay
> much attention, but now I wish whoever it wa had elaborated a little on
> that.  How about it, what is the difference?
> GM
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-- 
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  we are jailing people because the government may disagree with
  their beliefs,"

Naive Comment of the Year by the attorney for a "material witness,"
being held by the US "Justice" Dept. in violation of the constitution.

              <www.self-gov.org>


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