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PW-70 review

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  • PW-70 review

    I just put together an MP3 player for my car using an EPIA-M10000 motherboard and the PW-70 power supply. I drove from Provo, UT to San Diego, CA and back last weekend and it performed flawlessly. The trip was 9-10 hours each way, plus a few hours of driving around while I was there. It didn't have any problem with the 14+ Volts coming from my car, though it would shut down when starting the car - a tank circuit should take care of that.

    My power needs were modest - 1 2.5" hard drive, a USB joystick, and a CrystalFontz 4x20 LCD display.

    Installation is simple - just plug it into the motherboard and give it a good ~12V supply. it's compact size and on-motherboard mounting allowed me to build a very small enclosure (carpeted to match my subwoofer).

    Matt

    P.S. You can get the PW-70 at http://www.mini-box.com/pw-70.htm for $49.95.

  • #2
    Re: PW-70 review

    Originally posted by utahrc



    P.S. You can get the PW-70 at http://www.mini-box.com/pw-70.htm for $49.95.

    Yaa, any transients that come from your car into the power supply can damage your motherboards 12 volt systems. If you are usinga Laptop drive, that probably mitigates some of it.

    Your fan speed will probably change as you rev your engine... (assuming it idles slow enough..)
    MPEGBOX - Plexiglass Computer
    www.mpegbox.com

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    • #3
      Could someone post a close up picture of the power supply and read the numbers off the chips on it if they are not readable in the pics. I would like to get and idea of how that power supply is made and if it has any regulation on the 12V at all.
      ________________________________
      Via Epia M9000, Opus, and a cool custom case. All in my Saabaru 9-2X Aero.

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      • #4
        Originally posted by Trottingwolf
        Could someone post a close up picture of the power supply and read the numbers off the chips on it if they are not readable in the pics. I would like to get and idea of how that power supply is made and if it has any regulation on the 12V at all.
        It doesn't

        It connects a mosfet from the input to the output when the main rails are suppose to come on.

        -Jeff
        MPEGBOX - Plexiglass Computer
        www.mpegbox.com

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        • #5
          yeah thats what i thought but i would also like to know what regulators and mosfets are used
          ________________________________
          Via Epia M9000, Opus, and a cool custom case. All in my Saabaru 9-2X Aero.

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          • #6
            The mounting is such that I cannot easily remove the power supply - the hard drive mounting rails go right over the top of it. I can take a picture of the top side but, as I recall, most of the components are on the other side of the circuit board.

            Regarding the lack of filtering, risk of transients, etc., I understand that damage is possible, but after seeing so many accounts of people using similar DC-DC supplies in their cars without problems, I figured I'd be willing to take the risk.

            I'll post a follow-up if I end up with a fried motherboard or drive.

            Matt

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            • #7
              why not just spen $5 and build you one of these
              2007 Honda Fit Sport 1.5L SOHC-VTEC

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              • #8
                'Cause I'm not smart enough to figure it out on my own. :-) Looks like something easy enough to add when I build my tank circuit. Question though: What happens when Vin > 14V? As I recall, my voltage may go as high as 14.4 or so.

                Matt

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                • #9
                  well, you already planned on the voltage to go that high, im assuming that the raised voltage will give a higher output(maybe something like 12.5 volts?) so its still less than the original 14.4


                  this circuit is said to handle up to 15VDC input, just an expansion on the first circuit i posted.
                  2007 Honda Fit Sport 1.5L SOHC-VTEC

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                  • #10
                    The problem with those 12V regulators is that they have a votage drop of a little over a volt about 1.5V. When your car is above 13V every thing is fine, but if you turn the engine is off and your battery is at 12V then that regulator puts out about 10.5ish volts. So this means that this may not work when the car is off.
                    ________________________________
                    Via Epia M9000, Opus, and a cool custom case. All in my Saabaru 9-2X Aero.

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                    • #11
                      Originally posted by binary.h4x
                      well, you already planned on the voltage to go that high, im assuming that the raised voltage will give a higher output(maybe something like 12.5 volts?) so its still less than the original 14.4


                      this circuit is said to handle up to 15VDC input, just an expansion on the first circuit i posted.
                      What is the point of that top diode?

                      Nevermind, I just read the data sheet.

                      I wouldn't use tantalum caps in a car. In fact, I wouldn't use them at all. They catch fire. You can get better ceramics and Electrolytics for less money. Plus you need your tantalum derated at 50%. With your 24 volt transient supressor, that is a really expensive Tantalum.

                      -Jeff
                      MPEGBOX - Plexiglass Computer
                      www.mpegbox.com

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                      • #12
                        Originally posted by Trottingwolf
                        The problem with those 12V regulators is that they have a votage drop of a little over a volt about 1.5V. When your car is above 13V every thing is fine, but if you turn the engine is off and your battery is at 12V then that regulator puts out about 10.5ish volts. So this means that this may not work when the car is off.
                        I thought in the specs that they said they only work above 13.5V or something like that, leading me to believe that you wouldn't notice it when your car was giving you voltage between 12 and 13.5V. Can anyone else confirm?

                        Glad to hear you didn't have trouble with your 14.4V. That's about what my car outputs as well. Before I didn't have room for the regulator, but I do now, so I'll probably build one. I'm surprised no one on these boards is building them and selling them for $10 or $15.

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                        • #13
                          The manufacturer has taken a big risk biulding these supplies this way. There could very possibly be many people with blown boards and drives giving very negative feedback in the future due to the way they have taken the approach with the 12v. I noticed when i turned on the battery charger or turned it off, the speed of the CPU fan changed. And I was thinking, "hrm..that shouldn't happen this is supposed to be regulated"

                          So the 12v has no regulation at all. Any transients that happen, sparks on relays in the car, alt whine, pops anything at all, will filter striaght through into your PC. The power supply most prob does have some filtering, but if its unregulated, a fair heap of garbage goes through. Can we use a sproggy like circiut for the 12v part to really make it bullet proof?
                          Ford XR6T blueprint 4.0 L twin cam turbo.
                          Xenarc 7" touchscreen M10000 Audigy 2 NX
                          ITX 120W PS 80gig HD, 256MB Ram, USB wireless internet/LAN
                          Griffin Powermate Panasonic DVD-CDW
                          Pioneer 5x7 Four way, 2x12 pioneer subz
                          600watt 6chan USA audio AMP

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                          • #14
                            So which devices use the 12V line? I'm pretty sure that the motherboard and integrated devices do not. I know my 2.5" hard drive doesn't. The fan does, but I imagine that it is more tolerant of voltage fluctuations than other components might be.

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                            • #15
                              I thought in the specs that they said they only work above 13.5V or something like that, leading me to believe that you wouldn't notice it when your car was giving you voltage between 12 and 13.5V. Can anyone else confirm?
                              The specs mean that the voltage regs only regulate down to 12V corectly if they have 13.5V or more in. If they have less than 13.5V in then the output will be less than 12V. This is because the Voltage regulator drops the voltage that comes in by at least 1.5 volts. Fore example if you have 14V in the regulator drops it by 2V making 12V. If you have 13.5V drops by 1.5V you get 12V. If you have 12V in then it drops that by 1.5V you get 10.5V out. This is why they work great when the car is on(alternator at 14.4ish volts) but when the car is off the battery is at about 12 to 12.5ish volts so you get 10.5 to 11 volts out. I was using one of these regulators for a while so I could never run my carputer with the car off. Now I use the 12V regulator from the sproggy that uses the lm2587 flyback regulator. If you want 12V out with less than 13.5 in then you need some sort of flyback regulator that will run in buck/boost mode.
                              ________________________________
                              Via Epia M9000, Opus, and a cool custom case. All in my Saabaru 9-2X Aero.

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