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- Newsgroups: sci.electronics
- Path: sparky!uunet!usc!sol.ctr.columbia.edu!ucselx!newshub.sdsu.edu!chemteca.sdsu.edu!massoud
- From: massoud@chemteca.sdsu.edu (Massoud Ajami)
- Subject: Re: How slow are halogen lamps?
- Message-ID: <massoud.46@chemteca.sdsu.edu>
- Sender: news@newshub.sdsu.edu
- Nntp-Posting-Host: 130.191.227.22
- Organization: San Diego State University
- References: <1992Aug21.225605.17036@sics.se>
- Distribution: sci
- Date: Sat, 22 Aug 1992 16:38:48 GMT
- Lines: 42
-
- 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!
- ---==< 110 >==---
-