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Thread: Too good to be true?

  1. #1
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    Too good to be true?

    Hey guys,

    http://www.procase.com.tw/dcdc.htm

    I'm hoping to use this to power my car pc, now i have one concern which i hope someone can answer for me, Am i going to need to run something infront of this to regulate the voltage at 12v as cars are normally around 13.6v right?

    If so what and does anyone have any scematics/suggestions?

    Thanks for your help!

    Tristan

  2. #2
    Maximum Bitrate eugenen's Avatar
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    Have to e-mail the place and see. I'm in the same boat with the ituner p.s., the maker says it will work fine from a car, but mine blew. It may have been a fluke thing and I just got a bad one, but till he e-mails me back I am playing it safe and adding an external regulator.

  3. #3
    Raw Wave hijinks21's Avatar
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    you'll probably want a 12v regulator in front of it since the input is only 11.4V~12.6V
    '98 Explorer Sport
    http://mp3car.zcentric.com (down atm)
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  4. #4
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    Thought that could be the way to go.

    Thanks for the info guys.

    Tristan

  5. #5
    Variable Bitrate slarty's Avatar
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    Does anyone know where to buy off the shelf DC to DC regulators. I have an EPIA M 9000 and and would like to regulate the power @ 12v 4.58 Amp but

    A) don't know how to build one
    B) Can't find one
    Lilliput 8", C134 EPIA-M 900 (Black), A1-ITX, 256 Mb RAM, 40 Gb HDD, DVD, 802.11g, mini keyboard

  6. #6
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    That is essentially the same power supply that is inside the Casetronics cases. I have had this setup in my truck for about 6 months or so, without a regulator, and currently have no issues with operation. I measured voltage with both the truck off and running before I hooked it up. I had a rock solid reading in both states (12.3V and 14.4V respectively), and felt that the voltages were reasonably within tolerance for this application. (If you don't believe me, just meter any external power supply, and compare that to the rated output).
    KG6OQD
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  7. #7
    Variable Bitrate slarty's Avatar
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    Many thanks AVGeek so you fused it @ 5 AMP?

    I looked at the www.checkercube.com C134 and that is rated @ 12v 5Amp and its the same board that I have which is the EPIA-M 9000. The PSU they supplied me was 12v 4.58 AMP. Not knowing that much about tolerances I kind of surmise that I an rate the EPIA with any 12v supply @ 5 AMP from any Auto electrics shop?

    I also ordered the C134 whilst I was on site
    Lilliput 8", C134 EPIA-M 900 (Black), A1-ITX, 256 Mb RAM, 40 Gb HDD, DVD, 802.11g, mini keyboard

  8. #8
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    14.4V is *far* outside of the accepted range for the +12V rail, and can lead to hard drive / CDrom / DVD damage, especially if you have a noisy system with spikes.

    My +12V output of my PSU is 12.8V. This may seem like it's far out of wack, but the tolerance is +/-10%... that means 10.8V to 13.2V. 14.4V is far outside of that range (double the tolerance) and people have reported issues. You might get away with it for a while, but it can come back to haunt you. Additionally if you leave the computer running for a while you can brownout your device, which can also cause damage.

    What you can do instead is just regulate the +12V output of the PSU instead of the +12V input (this way you need a much smaller regulator). You can pick up a cheap +12V linear regulator that will work with the car on or off, not very efficient, but much better than nothing (cheap meaning like $2). Look for a LM340-12 or something similar.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  9. #9
    Maximum Bitrate eugenen's Avatar
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    Well mine must have been a faulty p.s. I sent it back and they are replacing it so when it returns I will try again. I put a lm1084 in front of my spare on just to be safe for now. I'm thinking of just soldering a 14v zeener across the input just for extra protection just to be safe.

  10. #10
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    On the input everything can most likely take whatever power the car provides, as those regulators are made for a voltage range of up to about 40 volts usually. The big problem will be for the 12V output, that's where you'll need to be careful.

    I don't know that a 14V zeener will do you much good (if anything at all), you'd probably be far better off with a large capacitor to try to filter out some of the AC and voltage spikes/drops.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

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