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Thread: totally lost on power supply

  1. #11
    Constant Bitrate firstorbit84's Avatar
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    first of all, if you're trying to use an asus eeepc 701, it only needs a 9.5v DC source. I powered mine with a $5 car charger adapter from dealextreme.com: http://www.dealextreme.com/details.dx/sku.19383

    basically i just used that 12v-9.5v adapter hardwired to a fuse and a 12v source that only turns on with the ignition in the on position. Then I just soldered a couple wires from the power switch of the EeePC to a push-button switch and relocated it to the dash to turn it on. So, in my setup the battery will charge whenever the car is on and it won't charge when the car is not on, but it can still run off the battery for a while... for example when it's shutting down. check out my build thread for more info.

  2. #12
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    ^^^
    Right now I've got it hard wired in with a car adaptor spliced into a 12V source, unfortunately if the car is not running there is not enough power from the adaptor to run the external usb hard drive. And the PC will constantly switch from AC to battery modes, with the pop up constantly flashing on the screen. Pretty annoying. One of the most frequent thing I use the PC for is to flash different tunes to the cars ECU, or to check the ECU learned history for fueling and timing. This requires the ignition to be on, but the engine off. So while I do this I constantly have it switching from battery to AC.

  3. #13
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    Quote Originally Posted by soundman98 View Post
    being that there really aren't any pic's of the wires, and i don't own this particular power supply, i am going off the manual for connections... so just keep in mind that some of this might be a shot in the dark..


    the connector on the left:

    the white wire(pin 3) connects to a switched power source to tell the power supply to tell the computer to turn on. the manual is very vague about this, so i assume that it is a standard remote input signal which should be a +12v signal..


    the red wire (pin 4) connects to the battery-- just make sure to fuse the wire within 12" of the battery.

    then the black wire-- which i assume connects to pins 1+2 gets connected to ground-- typically the car chassis-- usually bolted down(i usually use existing bolts/screws for this)


    above the main power input, is the PSW connector-- these wires connect to the motherboard power switch to tell the pc to turn on and off. i do not see any indication of wire color, or polarity listed in the manual for this set of wires.


    about in the middle of the board is VAUX-- this is unregulated power, and the manual states that this can be used for external devices that need to turn on with the power supply(like a monitor, or speaker amp)


    on the far right of the board, is the output voltage-- pins 1+2 are ground(negative),and i assume use a black wire, and pins 3+4 are positive-- i assume they use a yellow wire..



    OK, I think I'm getting this:

    here is a picture for reference:


    OK so the wires on the left (these are the Red,White and Black ones). I take the white one and wire it to a 12V source that turns on off with the cars ignition, say the radio or the cigarette lighter. The red one I wire straight to the battery (with a fuse), and the black I ground to the chassis. I plug small black and red wires into the mother board.
    Then the wires on the right (the yellow and black ones), there are two yellow wires and two black wires. Is this two positives and two negative to power the computer and one oter device, say an external hardrive? I just need to cut off the plug off the end of my power adaptor and wire it to one black and one yellow and wire, then plug into the computer like normal right?

  4. #14
    Raw Wave
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    Like I said, a 3A linear converter...

    But having recently been made aware of these cheap (eg) DC Power Modules, why bother with linear?


    PS - ooops - delayed response.
    You'd normally want a low voltage sensing or off option etc - I thought off with ignition etc was ok in your case....

  5. #15
    MySQL Error soundman98's Avatar
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    correct.

    i believe they offer 2-yellow and 2-black wires for devices that take more power then one wire will supply, so you should be able to tie both yellow, and both black together, and then connect them to the device.


    Quote Originally Posted by OldSpark View Post
    Like I said, a 3A linear converter...

    But having recently been made aware of these cheap (eg) DC Power Modules, why bother with linear?

    i was really happy you posted these for a separate project i was working on until i read the last part:
    "Note: output is always higher than the input by 1.0V
    Example: Input 6V, output is 7V~35V adjustable "

    though it appears they have another model that is opposite..(though no better then the sharp low loss v-reg's i was planning on using anyways)

  6. #16
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    Quote Originally Posted by OldSpark View Post
    Like I said, a 3A linear converter...

    But having recently been made aware of these cheap (eg) DC Power Modules, why bother with linear?


    PS - ooops - delayed response.
    You'd normally want a low voltage sensing or off option etc - I thought off with ignition etc was ok in your case....
    I'm sorry. I don't understand what I do with that or why I might need it. Doesn't it do the same thing as the part I have?

    So in my last post am I correct about how to hook it up?

  7. #17
    MySQL Error soundman98's Avatar
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    Quote Originally Posted by OUScooby View Post
    I'm sorry. I don't understand what I do with that or why I might need it. Doesn't it do the same thing as the part I have?
    yup-- it is a different solution to the same problem..

    Quote Originally Posted by OUScooby View Post
    So in my last post am I correct about how to hook it up?
    yup, your correct.

  8. #18
    Raw Wave
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    I think soundman98 indicated the wiring is correct. (I don't know.)
    EDIT - Yup, he did (above).

    My last reply was started before your previous 2 replies - hence the confusion... I was referring to an earlier reply and the use of "cheap and simple" linear regulators (that usually require at least 11.0V for a 9.5V output) compared to probably just as cheap but ready-made switch-mode (SMPS) dc-dc converters that can convert from an input of (eg) 3.5VDC to ~28V DC for an output of 9.5V (or anything between 5-35V DC) at 3A (with an added heatsink) for under $10. (IE - great voltage stability; and only ~3W of heat compared to up to 10W for the linear at 9.5V 2.135A output.)
    Mind you, that was before I realised my blunder wrt to that particular linked example for your use - but more on that below....


    FYI - another circuit I just happened to find (whilst looking for something totally different of course!! ).
    ... circuit-lab.com's A 12V Car Charger For ASUS Eee Notebook


    Now, my blunder....
    Quote Originally Posted by soundman98 View Post
    i was really happy ... until i read...
    "Note: output is always higher than the input by 1.0V"
    Oooops!
    Er - I must have meant .. er, um, as an EXAMPLE of offerings...

    But soundman98 - thanks, and thanks !
    First for your "happiness", 2nd (and Ye!) for the comment -cum- sanity check.

    The first should actually go to another that recently PM'd me the link (LOL! And He seeks MY input... ha!).
    Maybe I could palm the blame to him, but he was after an up-converter to power a distant 12V load from a local 12V supply, so I'm the idiot for posting hereon without checking up/down conversion. (I was so impressed by the price etc!)

    So a big apology to OUScooby and readers for my potentially costly blunder!


    I'm certain I have seen similar products for both up/down conversion.... (Maybe another supplier?)
    But let that be a lesson to those that trust people that generalise and skim specs and products instead of a reasonable investigation, or those that confuse different applications (eg - a voltage booster for distribution losses versus a voltage reducer if not also booster).

    I think I'll de-rim some tyres to clear my head and some pretty smooth & soft skin.
    Ok - clear my head and hack old keyboard warrior hands. (You guys are just too good for me.)

  9. #19
    MySQL Error soundman98's Avatar
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    a little OT, but i guess you could use both-- use this one to keep the input above 15v, and then use this one to keep it at 12v..

    and it would still be a full-featured 12v, 2A buck/boost reg. for less then $20...

  10. #20
    Constant Bitrate firstorbit84's Avatar
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    man, you guys are really making a simple problem very complicated.

    Scooby, I think your problem with the original DC-DC converter that you purchased was that it was set up to do 9V and not 9.5V. Once you figure out which converter you want to use to get 9.5V then I would suggest powering your external hard drive from a separate converter.

    Like I said earlier, I have had no issues whatsoever using the $4.60 Car charger from Dealextreme that I hardwired with a 3A fuse into an ignition-on switched 12V source. I also run multiple devices through the laptop's USB ports, including a usb hub, GPS, touchscreen controller, Bluetooth, ipod, flash drive, microSD reader, and keyboard.

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