RE: [CAD_CAM_EDM_DRO] Re: AC to DC question, old worklight OT
Posted by
Andy Wander
on 2004-10-01 06:01:15 UTC
Just to add a few tidbits of info to this:
1) In all incandescent lamps(bulbs!) the filament is continually losing
tungsten to evaporation. In a standard light bulb(non-halogen) this
evaporated tungsten migrates to the inside of the "bulb" and condenses there
on the glass, which is cool enough to be below the evaporation temperature
of tungsten. That's why old light bulbs get that blackened look, and
eventually(if it doesn't get shocked into breaking first) a portion of the
filanment will be evaporated away completely,and the lamp(bulb...) blows.
2) That's why halogen lamps(ok, bulbs) are so small-the "envelope" or
"glass" has to be close enough to the filament to stay hot enough so that
the evaporated tungsten from the filament can't condense on it. The halogen
gas inside the lamp(bulb!! This is really difficult for me:)) helps in the
process of carrying the tungsten back to the filament and redepositing it.
That's why halogen lamps last longer.
3) The need to keep the "bulb" hot enough for #2 is why they usual special
glass, originally(maybe still) quartz glass, which can resist the heat
without melting. That's why they used to be called "quartz-halogen" or
"quartz" bulbs(there, I said bulb without putting a comment that it's really
lamp-or did I?:))
Andy Wander
Vice President, Engineering
Verrex Corporation
(908) 232-7000
(908) 232-9065
(610) 847-5947 Home Office (Wednesdays)
(610) 389-4819 Cell
-----Original Message-----
From: Jeff Sauer [mailto:jsauer@...]
Sent: Friday, October 01, 2004 12:40 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: AC to DC question, old worklight
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "volitan712003"
<volitan@o...> wrote:
Not to beat a dead horse, but I have designed several
high power, high reliability halogen bulb regulator
circuits for precision lighting applications in the
semiconductor test equipment industry. Here are a few
technical tidbits...
Halogen bulbs actually run better on AC. The quartz
bulb envelope will prematurely blacken with evaporated
tungsten at one end if DC power is used.
Bulb life depends on applied voltage... 10% overvoltage
cuts bulb life in half! 10% under doubles bulb life. But
20% under is very bad for life because the quartz envelope
gets too cold for proper "Halogen" operation. When this
happens, tungsten starts condensing on the inside of the
bulb and the filament evaporates away. When the bulb is
really hot (normal rated voltage applied) the tungsten can't
condense on the glass and actually re-forms back on the
filament... hence the increased lifetime even at very
white hot filament temperatures.
A good halogen bulb manufactuer (like Usheo) has this
kind of bulb data on line so you can check it out youself
to be sure that you are running the bulb under optimal
conditions.
Regards... Jeff
Addresses:
FAQ: http://www.ktmarketing.com/faq.html
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OFF Topic POSTS: General Machining
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bill
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1) In all incandescent lamps(bulbs!) the filament is continually losing
tungsten to evaporation. In a standard light bulb(non-halogen) this
evaporated tungsten migrates to the inside of the "bulb" and condenses there
on the glass, which is cool enough to be below the evaporation temperature
of tungsten. That's why old light bulbs get that blackened look, and
eventually(if it doesn't get shocked into breaking first) a portion of the
filanment will be evaporated away completely,and the lamp(bulb...) blows.
2) That's why halogen lamps(ok, bulbs) are so small-the "envelope" or
"glass" has to be close enough to the filament to stay hot enough so that
the evaporated tungsten from the filament can't condense on it. The halogen
gas inside the lamp(bulb!! This is really difficult for me:)) helps in the
process of carrying the tungsten back to the filament and redepositing it.
That's why halogen lamps last longer.
3) The need to keep the "bulb" hot enough for #2 is why they usual special
glass, originally(maybe still) quartz glass, which can resist the heat
without melting. That's why they used to be called "quartz-halogen" or
"quartz" bulbs(there, I said bulb without putting a comment that it's really
lamp-or did I?:))
Andy Wander
Vice President, Engineering
Verrex Corporation
(908) 232-7000
(908) 232-9065
(610) 847-5947 Home Office (Wednesdays)
(610) 389-4819 Cell
-----Original Message-----
From: Jeff Sauer [mailto:jsauer@...]
Sent: Friday, October 01, 2004 12:40 AM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: [CAD_CAM_EDM_DRO] Re: AC to DC question, old worklight
--- In CAD_CAM_EDM_DRO@yahoogroups.com, "volitan712003"
<volitan@o...> wrote:
> There's a sign near the light that says to use aHi David:
> 24v, H3 Halogen bulb.
>
> David
Not to beat a dead horse, but I have designed several
high power, high reliability halogen bulb regulator
circuits for precision lighting applications in the
semiconductor test equipment industry. Here are a few
technical tidbits...
Halogen bulbs actually run better on AC. The quartz
bulb envelope will prematurely blacken with evaporated
tungsten at one end if DC power is used.
Bulb life depends on applied voltage... 10% overvoltage
cuts bulb life in half! 10% under doubles bulb life. But
20% under is very bad for life because the quartz envelope
gets too cold for proper "Halogen" operation. When this
happens, tungsten starts condensing on the inside of the
bulb and the filament evaporates away. When the bulb is
really hot (normal rated voltage applied) the tungsten can't
condense on the glass and actually re-forms back on the
filament... hence the increased lifetime even at very
white hot filament temperatures.
A good halogen bulb manufactuer (like Usheo) has this
kind of bulb data on line so you can check it out youself
to be sure that you are running the bulb under optimal
conditions.
Regards... Jeff
Addresses:
FAQ: http://www.ktmarketing.com/faq.html
FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
timg@...
Moderator: pentam@... indigo_red@... davemucha@...
[Moderators]
URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
OFF Topic POSTS: General Machining
If you wish to post on unlimited OT subjects goto:
aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it if
you have trouble.
http://www.metalworking.com/news_servers.html
http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
sister site to the CCED group, as many of the same members are there, for OT
subjects, that are not allowed on the CCED list.
NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
bill
List Mom
List Owner
Yahoo! Groups Links