🚀 go-pugleaf

In article <1992Aug21.225605.17036@sics.se> boortz@sics.se (Kent Boortz) writes:



>I have noted that when halogen stage lights go of (500-2000W) there is
>a delay before the light is gone. Is the response to voltage changes slow
>for halogen lights? I was thinking of controlling a TRIAC with a
>microcontroller and one idea is to use patterns of AC half periods that is
>on or off. A 50% setting would be one halfperiod (hp) of and one on.
>A 75% setting would be 3 hp's on and one off. Switching the TRIAC on and
>off at the zero crossing point would eliminate the need for filtering away
>unwanted electro-magnetic interference.

>The problem is flickering for low settings. A 10% setting will give 9 hp's
>off and one hp on. But if the halogen lamp is slow in response it will
>eventually be no problem. Anyone know?


>Kent Boortz
>boortz@sics.se
>--
>Kent Boortz
>boortz@sics.se

Halogen lamps have no delay in turning off, it is the temperature of the 
filament which shows such action. If you increase the temperature of a 
normal light bulbe with tungsten filament (increase the current), the 
tungsten starts to vaporize, and it coats a film on the glass shell. This 
action reduces the intensity of the lamp, so defeeding the purpose of 
intensifying the light (any burned lamp has a black spot on the glass or 
somewhere else). By putting halogen gas in the tube, halogen will bring 
the vaporized tungten back to the fillament, so there wouldn't be any 
coating, therefore, you can run the filament in higher temperature, and get 
brighter light.

Pulsing the lamp does not let halogen lamp act as halogem lamp (low filament 
temperature), and also to some extend, the filament integrates the 
pulsation, and no flickering happens.


Peace and Prosperity!
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