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#37099 - 04/21/04 12:54 PM AC vs. DC
jerrytyler Offline
Junior Member

Registered: 04/21/04
Posts: 2
Loc: 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 04:21 AM Re: AC vs. DC
C-H Offline

Member

Registered: 09/17/02
Posts: 1508
Loc: 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.

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#37101 - 04/22/04 06:25 AM Re: AC vs. DC
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: 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!

on the 'Ass-U-Me" word usage!!!

Scott35
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

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#37102 - 04/23/04 07:42 PM Re: AC vs. DC
cpalm1 Offline
Member

Registered: 01/06/04
Posts: 62
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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