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#37099 - 04/21/04 03:54 PM AC vs. DC  
jerrytyler  Offline
Junior Member
Joined: Apr 2004
Posts: 2
Atlanta,GA, USA
Hi y'all. I've really enjoyed reading the stuff on this site, and now I have a question.
I am a lighting distributor, and we sell quite a bit of low voltage lighting. Most of the transformers that come with the fixtures are AC, but certain systems come with DC transformers, and I can't seem to get a straight answer about why, or what the difference would be. The only clue I have is that the DC transformers come with these cable lighting systems you might have seen, so I think this may be a voltage drop issue?

Thanks for any help!

Jerry


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#37100 - 04/22/04 07:21 AM Re: AC vs. DC  
C-H  Offline
Member
Joined: Sep 2002
Posts: 1,497
Stockholm, Sweden
Modern electronic transformers (switching mode power supply) output high frequency AC. This means that long cables will cause radio/TV/etc. interference.

Adding a rectifier circuit means greater cost to the manufacturer, lower efficiency and less power.


#37101 - 04/22/04 09:25 AM Re: AC vs. DC  
Scott35  Offline

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Joined: Oct 2000
Posts: 2,707
Anaheim, CA. USA
The Low Voltage Incandescent Lamps "May" run a little better using DC instead of AC (well filtered DC as opposed to AC), but the most apparent reason would be to drive LED type Lamp arrays.

Wish I had a definite answer for you, but not knowing the specifics per installation / usage / equipment types, I can only "Ass-U-Me" these two things!

[Linked Image] on the 'Ass-U-Me" word usage!!!

Scott35


Scott " 35 " Thompson
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#37102 - 04/23/04 10:42 PM Re: AC vs. DC  
cpalm1  Offline
Member
Joined: Jan 2004
Posts: 66
some high quality low voltage light fixtures use DC to improve bulb life. incandescent bulbs last longer on filtered DC than AC. this is because filtered DC is a smooth current while AC has a 60 Hz frequency which causes the filiment of the bulb to vibrate. the vibration shortens the bulb's life



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