home *** CD-ROM | disk | FTP | other *** search
- Newsgroups: rec.photo
- Path: sparky!uunet!munnari.oz.au!uniwa!cujo!cc.curtin.edu.au!zrepachol
- From: zrepachol@cc.curtin.edu.au
- Subject: Re: Lamp intensity vs. lifetime
- Message-ID: <1992Nov24.042853.1@cc.curtin.edu.au>
- Lines: 23
- Sender: news@cujo.curtin.edu.au (News Manager)
- Organization: Curtin University of Technology
- References: <Bx8CA2.GF2@ns1.nodak.edu> <Bx93z4.n2B@cs.dal.ca> <1992Nov16.164101.20150@bnr.ca> <BxvICz.rs@javelin.sim.es.com> <1992Nov18.172117.21297@Happy-Man.com>
- Date: Mon, 23 Nov 1992 19:28:53 GMT
-
- In article <1992Nov18.172117.21297@Happy-Man.com>, josh@Happy-Man.com (Joshua_Putnam) writes:
- > In <BxvICz.rs@javelin.sim.es.com> rspeirs@javelin.sim.es.com (Ron Speirs) writes:
- >
- ...
- Lamp life is ~= to the 3rd to 4th power of the applied voltage. The 2 killers
- of lamps are 1 ( for big spots etc ) thermal stress at power on. Stage lighting
- techs will pre-heat the lamps for upo to 20 min before use, and only dim down
- to a low output. IE, if you look at the lamp, it is quite a bright red, but
- provides nearly no illumination on the stage/set. 2 switch on surge. A cold
- filament has a resistance of only a few ohms... hence LARGE currents and
- large magnetic fields pulling the filament apart. This is why 90% of the
- 'pop... damm's happen when you turn on the light. A 'soft-start' dimmer will
- increase lamp life by ~4 fold in many cases.
-
- A good thyristor dimmer should not cause too much buzzing. The buzz realy gets
- going at the very low end of the range, and you probably shouldn't operate the
- lamp like that any way.
-
- BTW, some quartz-halogen globes will fail very quickly if run at a reduced
- voltage. Check the data sheets.
-
- ~Paul
-
-
