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Power options for Ultimarc marquee light
epetti:
I got the ultimarc marquee light for my marquee. I know it uses 12V rather than 110V. I'm wondering, other than wiring to the PC power supply, is there any reason I couldn't get a cheap 12V power adapter from Radio Shack, snip off the top, and wire to that and plug it straight into the power strip? Any other options? Anyone know what the amp requirements for it are?
Thanks.
BobA:
Which Ultimarc marquee light?
epetti:
The one at the bottom of this page:
http://www.ultimarc.com/controls.html#cabparts
BobA:
Cold cathode lights take very little power so your current draw will be low. Don't know the exact figure for that light but others of similar size take 5 ma. at approx 700v.
Here is an analysis of the power draw with a 12V supply found on Toms Hardware.
"These guys work, as you probably have figured out, by taking your 12V supply and jacking it up to a high voltage (and lower current) to run the lamp.
Any 12V DC supply should work, and probably a few volts above or below. An important thing is how much power you need. I would assume the 5mA is the inverter output, not the input. I know these lamps take around 2-5W, depending on size, so that sounds right: 680V x .005A = 3.4W
Then you figure how much current that ends up on the 12V side: 3.4W / 12V = .283A or 283mA. Add in some extra current to account for efficency, (the inverter will be anywhere from 60-90% depending on the design) and you're looking at around 500mA for the 12V supply.
Lots of wall warts are available in that range. I'd give that size a shot, and measure the voltage when you fire it up. If it dosen't drop more than a few volts, you should be fine. Inverters aren't very critical on input voltage."
Hope that helps
epetti:
Very helpful. Thank you.
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