Hooking up Cold Cathodes to a desk. No power Supply.

Discussion in 'Buying Tips and Advice' started by AlmightyG5, Nov 25, 2005.

  1. AlmightyG5 macrumors 6502

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    #1
    Hey, is it possible to hook up cold cathodes with out plugging them into a computer power supply? The power supply give 12Volts DC. Can't i just use a DC plug that converts 120 V AC to 12V DC from a wall socket, splice the wires and hook them up to the cold cathode inverter? I want to get two 12" blue cathodes and put them behing my desk so they illuminate the wall. Whats the best way to do this without a computer power supply.
     
  2. AlmightyG5 thread starter macrumors 6502

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    #2
    If i were to do cut the molex connector from the Cold Cathode kit...-

    [​IMG]


    and then take a 12V DC plug and cut that...-

    [​IMG]

    Can i then combine the wires and get the same effect as using the molex connector and plugging it into a power supply in a PC?-

    [​IMG]
     
  3. iMeowbot macrumors G3

    iMeowbot

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    #3
    Sure, just make sure that the power output from the wall wart (the mA rating) is higher than the rating of the lamps, so you don't end up with a lump of molten plastic where the transformer used to be.
     
  4. ITASOR macrumors 601

    ITASOR

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    #4
    Why not just run them off a cheap power supply? Wouldn't that be safer/easier?
     
  5. Will Cheyney macrumors 6502a

    Will Cheyney

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    #5
    Haha! Brilliant! Well done.
     
  6. AlmightyG5 thread starter macrumors 6502

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    Well i'm thinking of getting a AC wall adapter that has 1000mA. The lights run from 200-800mA or something so that should be good right? I have a 12V DC power adapter right now...but it is only 500mA, and i think 1000mA would be safer.

    Here's a link to the AC power adapter-http://www.electronix.com/catalog/product_info.php/cPath/265_336/products_id/1561
    This should work... right?
     
  7. homerjward macrumors 68030

    homerjward

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    #7
    i agree with itasor. you can get an el-cheapo power supply from newegg or similar for 15ish bucks, possibly the same in a local store after rebates. it'd be much easier and you could just hide it behind the desk, especially if you get a micro-atx power supply. it'd probably be best to get as low a rating as you can, because really cheap power supplies like that can be 60% or worse efficiency, and at 60% efficiency a 300 watt power supply (v. low end) sucks down 500 watts :eek:
     
  8. iMeowbot macrumors G3

    iMeowbot

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    #8
    If that's 800mA each and you have two, you'll want a 1.6A or larger supply to carry the load. Yeah, I'm being kind of a ninny about this but a beefy enough supply is a heck of a lot cheaper than a fire -- and those little wall transformers do melt down if they're overloaded.

    If you don't want the bulk of a PC power supply, you might look into transformers intended for laptops.
     
  9. AlmightyG5 thread starter macrumors 6502

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    #9
    I think i'm wrong about that...

    I found this article: "Even with both tubes plugged in, the SunBeam kit starts out drawing only about 170mA at 12 volts, versus 270mA or more for newer kits. The SunBeam tubes did this with other inverters, and the SunBeam inverter did this with other tubes, so I thought all of the SunBeam components were weak.

    As it turned out, though, the SunBeam kit just started dimmer, and took longer to warm up, than the newer kits. After a few minutes of run time, it made it up to the same brightness as the other kits, and a 550mA current draw."

    found here:http://www.dansdata.com/glowthings.htm
     
  10. AlmightyG5 thread starter macrumors 6502

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    #10
    And i also found this: http://www.tech-forums.net/showthread.php?s=&threadid=5651

    This guy has the same idea as me...And he used a 1000mA power supply with dual cathodes. So i'm thinking 1000mA will be fine.

    "Bought 12V 1.0 mA adapter, spliced the yellow and black leads from a female molex to the +/- wires on the adapter, plugged it to the male molex on the cath tubes inverter, and PRESTO!!! - there was light!"
     
  11. iMeowbot macrumors G3

    iMeowbot

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    #11
    If it works, it works, but I'll make one more stab at playing mother hen here. Would you consider getting a little inline fuse holder from Radio Shack or something and wiring in a 1A fuse? If everything works you're only out two bucks, and if it blows you know it's time to consider a beefier supply.
     
  12. AlmightyG5 thread starter macrumors 6502

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    #12
    Are you talking about something like this?-
    http://www.radioshack.com/product/index.jsp?productId=2103770&cp=&kw=1a+fuse&parentPage=search

    and this-
    http://www.radioshack.com/product/index.jsp?productId=2062229&cp=&pg=1&kw=fuse+holder&kwCatId=2032058&parentPage=search

    So if the 1000mA power adapter fails...the fuse will break instead of damaging the power supply and/or lights?
     
  13. ITASOR macrumors 601

    ITASOR

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    #13
    Yes, and/or burning your house down.
     
  14. iMeowbot macrumors G3

    iMeowbot

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    #14
    The fuse will go if the lights put too heavy a load on the circuit, since 1A is 1000mA. It can save the power supply and you if the lights overload, and it would protect the lamps if a weird surge-like thing makes its way out of the power adapter, but it won't help if something inside the power adapter itself goes wrong (but the house fuse may help you out on that end).
     
  15. AlmightyG5 thread starter macrumors 6502

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  16. AlmightyG5 thread starter macrumors 6502

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  17. Eidorian macrumors Penryn

    Eidorian

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  18. aquajet macrumors 68020

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    #18
    But that's half the fun!!! :D
     
  19. iMeowbot macrumors G3

    iMeowbot

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    #19
    Yes it will, and with modern PC power supplies you typically also need to hook up your own power switch and will have a bunch of extra cables hanging out. Ugly.

    A Tripp-Lite PR-3 should be just about right for what you want to do, it's a nice simple 13.8V supply (13.8 is the nominal 12V you would get from a car) that will nicely handle a sustained 2A without issues. It sells for around $20-25. There are two insulated screw terminals on the front for simple hookup.
     
  20. AlmightyG5 thread starter macrumors 6502

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    #20
    Im not worried about the wire clutter because it will be under the one part of my desk that you can't see. You said that i will probaably have to hook up my own power switch.

    I found a power supply that in the description says:"features a 4-pin P4 and a 6-pin AUX power connector." Is this the power switch your talking about? Or just the connectors to connect to the power switch.

    Here is the link to it:http://www.xoxide.com/orion-xp400-420w-psu.html
    Does this power supply come with a power switch?
     
  21. doucy2 macrumors 65816

    doucy2

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    #21
    i think im gonna go with the old PS when i do this, alot easier and safer (i dont wanna melt the other one) its worth using up that extra space
     
  22. AlmightyG5 thread starter macrumors 6502

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    #22
    So will I need a power switch for This Power Suppy?

    If so will this work?:http://www.xoxide.com/acrylicpanel.html

    The thing is...I have a the power switch set from an old computer...but I lost the power switch... I just have the two LED lights, and a Reset button left...no power button. But i do have the little rectangle connectors (same connectors as the power switch above and pictured below) on the end of the wires of this set. So can i just take a switch i have lying around and put that rectangle plug on it, to plug into the power supply? would that be the same thing as a regular PC power switch.

    these are the rectangle plugs I'm talking about. I have these on my old power switch unit that just has two LED's and a reset button. Can i splice them and connect them to a toggle switch or something to make a power switch for the power supply?
    [​IMG]
     
  23. Eidorian macrumors Penryn

    Eidorian

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    #23
    That is a good point. All of the PC's that I've built have their power switch cables attached to the motherboard and the power supply is attached to the motherboard via a 20/24-pin connection as well. How will you turn the supply on without a motherboard?
     
  24. cubist macrumors 68020

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    #24
    Two points.

    First, wall transformers are not regulated, so they may put out too much voltage and damage the lamp. There is no danger of burning down your house. Get a big enough one, connect up the light, but check the voltage on the leads when it's running. (You could get the type that are sold for cars, they should be designed for more voltage fluctuation, but may need more power and cost more.)

    Second, PC power supplies check the load and won't work if there's not sufficient current draw. I used to use an old dead hard drive to test power supplies. I don't know how much power the cold-cathode light draws; you might need to connect up several of them. Edit: Get a used AT-type supply, not an ATX one - the kind with the Big Red Switch on the side.

    What I'd suggest is watch for a hamfest in your area, then go there and get a used open-frame 12V regulated supply. You should be able to get it for about a quarter. Hook that up and run all the lights you want.

    BTW, why do you want to put cold-cathode lights on your desk?
     
  25. AlmightyG5 thread starter macrumors 6502

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    #25
    The cold cathodes use only like 25 watts so power isn't an issue. Why can't i use ATX? Do I really need a power switch to turn it on...or can i just use the switch that is built on to the power supply? What is a hamfest and a used open frame 12V regulated supply? You are confusing....

    And I am not putting the lights on my desk...I'm putting them under with a sound reactive box so they blink to my music.
     

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