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Thread: Help with 12V to 5V step down converter.

  1. #11
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by Mickz View Post
    ^ What he said!
    Nirwana Project, the Android/Win 7 hybrid system!

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  2. #12
    MySQL Error soundman98's Avatar
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    wow, $17 for a switch mode 10A psu?!?! i almost bought a couple just for the price...

  3. #13
    Raw Wave
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    Ditto.
    It makes a farce of USB & 5V supply issues.

  4. #14
    Who am I? HiJackZX1's Avatar
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    Only thing I wonder is does this thing spit 5V right away? Does it have to get a certain heat before it drops to 5V or am I over thinking things again? I calculated out that everything on max will use 19.80 amps. So you think connecting 2 fans on the 5V side will be ok? They are the medium fans, found in most cases. I want to use two, but on 5V so its a steady breeze since you guys have me convinced it will not get extremely hot.
    Nirwana Project, the Android/Win 7 hybrid system!

    1X Ainol Novo Flame Tab
    4X MK808b
    3x Perixx Touchpads
    3x 7 inch Screens
    1X 7 inch motorized Screen
    1x Win 7 PC

  5. #15
    Raw Wave
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    So at 19.8A you'll use the 30A supply.


    The heat is irrelevant.
    They need a minimum load (typically ~10mA), but this should be inbuilt. Hence why "power on" LEDs are used, though otherwise 470 Ohm resistor. (That dissipates 1/20th of a Watt, hence trivial and cheap and should be built in.)

    FYI - the same minimal loading is found on many PSUs and regulators. I know some (pathetic) ATX supplies do NOT include that load... (That's looking for trouble, or more sales!)
    Even the linear LM317 requires it, but hence the choice of a "standard" 120 Ohm as one of its voltage-divider resistors - 120R across 1.2V is its 10mA minimum regulation current.


    PS - BTW, thanks for the link.
    Last edited by OldSpark; 10-06-2011 at 08:27 PM. Reason: ps

  6. #16
    MySQL Error soundman98's Avatar
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    Quote Originally Posted by HiJackZX1 View Post
    or am I over thinking things again?
    yes

    you know, i saw my first post in your most recent build log the other day-- it's not too late to change the title of your project!

  7. #17
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by soundman98 View Post
    yes

    you know, i saw my first post in your most recent build log the other day-- it's not too late to change the title of your project!
    NOOOOOOOOOOOO, Im almost done. The setup is actually working on my test bench. Havent tested the KVMP switches though with the touchscreens through those yet, since I havent had a chance to power them. Once I get that OPUS working, I can put the rig in the car and test the KVMP.

    As always thanx for the detailed advice. What do you think adding the fans will bring the load up to? Should I maybe figure in 2 amps per fan?
    Nirwana Project, the Android/Win 7 hybrid system!

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    4X MK808b
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    1X 7 inch motorized Screen
    1x Win 7 PC

  8. #18
    MySQL Error soundman98's Avatar
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    maybe half of that-- this fan is meant for industrial applications, and takes about 1A:
    http://www.parts-express.com/pe/show...number=259-122

  9. #19
    Constant Bitrate
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    I looked into one of these but never pulled the trigger. Looks like a good device nonetheless.

  10. #20
    Low Bitrate Zephrant's Avatar
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    Also worth noting: if you bolt it tight to a metal structure the metal adds to the heat-sinking capability of the case (as long as it's cooler than the device, i.e. not the exhaust pipe). I was just going to bolt mine to the trunk's cross-member support and call it good.

    The device is all electronic- it doesn't need to warm up or heat to work, it works hot or cold, from below freezing to +45C, according to your specs.
    Zotac H55-ITX w/ 802.11n WiFi, i3-550/3.20GHz, 8GB DDR3 1333MHz, 120G Intel SSD, P2140,
    7" pseudo-transflective resistive TS, Win7-64, Centrafuse 4.3, Elmscan Compact 6, BU-353, Rear camera, Trailer camera

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