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Thread: 200 Watt DC-DC PSU

  1. #41
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    Quote Originally Posted by STI_FFY
    Did you actually see a PW-70a that they stamped as PW-120 or did you guess from photos?
    My guessing ability is no where near that good.... It was a post on this forum a while back.... someone had a PW-120 from AudioForge and pulled off the PW-120 lable and it said PW-70A on the circuit board.

  2. #42
    Maximum Bitrate Rundell's Avatar
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    Was lookin at the www.mini-itx.com website and they sale them and have some info up on them: http://www.mini-itx.com/store/default.asp?c=10#p1808

    Can be used in vehicles, with this easy modification (PDF). Tip: don't use a full size optical drive in a vehicle. To use in a desktop machine, please use our 60W AC Adapter. Motherboard not included!

  3. #43
    Low Bitrate Deadnick's Avatar
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    Well I'm going to try mine out tonight with a Full Size ATX motherboard We'll see how it goes. The Ebay auction better not be wrong or I'll be returning this thing quicker then shizzle and leave bad feedback. I'll hook up a Hard Drive and CDROM too it also just to put it under a heavy load and we'll see what happens.

  4. #44
    Low Bitrate Deadnick's Avatar
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    I want a slot load DVD Where did you pick that up? I'm fiberglassing my screen into the dash this weekend and if I had one of those I would make a slot for it.

    Quote Originally Posted by mobileh1
    Thats a very interesting idea. I suppose so. The problem would be that the capacitor has to 'absorb' enough energy before it can provide its resovoir effect and provide power while the batteries are cranking the engine. So between the ignition switching on, and the voltage drop I would not think that there would be enough time for the capacitor to charge up. Typically a capacitor this capacious would be used very close to an amp to provide a little extra when the amp is drawing peak loads.

    Interesting thought though. I'll have to think about that some more. If it could be workable, it would certainly be a cost effective solution.

  5. #45
    Constant Bitrate STI_FFY's Avatar
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    Quote Originally Posted by Deadnick
    Well I'm going to try mine out tonight with a Full Size ATX motherboard We'll see how it goes. The Ebay auction better not be wrong or I'll be returning this thing quicker then shizzle and leave bad feedback. I'll hook up a Hard Drive and CDROM too it also just to put it under a heavy load and we'll see what happens.
    The 12V rail is unregulated on the PW-120-M as it seems to be on all the mini-box PW-xx supplies except I believe the PW-80. The ebay listing says it will power your motherboard cleanly (even in your car) but it says nothing about your hard drive being powered cleanly in your car.

    You might get lucky enough that things will work when you test, but I would strongly suggest that you use some form of regulation on the 12V supply that you intend to feed the hard drive and CD-ROM. The motherboard and fans won't care about the variability, of course.

    The mini-ITX site also cautions against the use of 3.5" hard drives with this design. If you feed the PW-120-M with some form of high-current 12 Volt boost/buck regulation you could certainly use your hard drive and CD-ROM in the car with no worries.

    A couple of ITPS could be used with their output combined, but this would not handle input (car) voltage dropping below 12V.

    Another issue is that the power supply supervisor will shut down the PW-120-M supply if the 12V rail goes above 14.5V.

    The mini-ITX site has a mod to permit the 12V car supply to exceed 14.5V without shutting down the PW-120-M supply. I see that my supply as it came from audioforge does not have this mod in place. I will probably apply it and then solve the 12V regulation problem somehow before I install this into the car.

    Mod

    Keep in mind that this supply cost only $70, a 250 watt boost/buck design with power sequencing built in (Opus) costs much more. The difference should be spent solving the 12 volt boost/buck regulation and sequencing issues. In the end, the Opus might end up being cheaper but not as much fun and less educational.
    SeeYa! -Jim-

  6. #46
    Maximum Bitrate Rundell's Avatar
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    Quote Originally Posted by STI_FFY
    A couple of ITPS could be used with their output combined, but this would not handle input (car) voltage dropping below 12V.
    Forgive me for not knowing too much about the ITPS. This is kind of in the opposite direction but I just want to clear a couple of things up. Unlike Deadnick I will be running a mini-itx mobo, a Laptop Hard Drive, And a Slimline drive. So I don't need regulation and I don't really need an ITPS. However I went ahead and got an ITPS since I want to use the auto on feature when I turn on my car. I know I may have to build a tank circuit. I can apply a soilder bump to bypass regulator so I can have more than 60W going through. My understanding is if I do this mod it will make it an auto on device strickly and nothing else. Is this correct?

    Thanks,
    Tim

    BTW: I notice how you have a WRX STI, very nice. My system is going in a Subaru Forester

  7. #47
    Constant Bitrate STI_FFY's Avatar
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    Quote Originally Posted by Rundell
    Forgive me for not knowing too much about the ITPS. This is kind of in the opposite direction but I just want to clear a couple of things up. Unlike Deadnick I will be running a mini-itx mobo, a Laptop Hard Drive, And a Slimline drive. So I don't need regulation and I don't really need an ITPS. However I went ahead and got an ITPS since I want to use the auto on feature when I turn on my car. I know I may have to build a tank circuit. I can apply a soilder bump to bypass regulator so I can have more than 60W going through. My understanding is if I do this mod it will make it an auto on device strickly and nothing else. Is this correct?

    Thanks,
    Tim

    BTW: I notice how you have a WRX STI, very nice. My system is going in a Subaru Forester
    Hi Tim. The ITPS has a 6A "polyfuse" on its input, so you should perhaps be able to get ~70W through it if you bypass the regulator. The sequencer can still be used, the onboard FET will still gate the output current and the pulse will still be applied at appropriate times when the ignition sense comes/goes.

    If you choose to use the regulator, then of course the power envelope is to a large extent dictated by how much cooling you provide the regulator/heatsink. The regulator itself is only rated for 5A even if you keep it chillin'. You could perhaps use all 60W but I suspect you'd need to provide a nice breeze, and if fan noise is annoying, well then...

    I am seriously considering using a laptop drive as well, but moreso for the ruggedness than the power consumption issues. I just wish they had more capacity. I may have to use multiple drives.

    I love my STI. I have never really enjoyed driving anything as much as I do this car. It makes the 45 minute drive to/from work in Rockville something to look forward to rather than dread - and after almost a year of ownership it still has no radio!

    I hope to get the sheetmetal from PHC in early June and get this thing installed.

    My wife has her eye on the Forester XT as her next vehicle (soon). I can't say I haven't been influencing her decision.
    SeeYa! -Jim-

  8. #48
    Constant Bitrate STI_FFY's Avatar
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    Specs for PW-120-M

    Many (most?) of you will be disappointed.

    +5.0V @ 10A 5%reg
    +5SB @ 2A 5%reg
    +3.3V @ 6A 5%reg
    -12V @ 0.1A 5%reg
    +12V @ 12A unreg.

    Whoa! 12A of 12V unreg - there's 3/4 of the 200W rating!
    SeeYa! -Jim-

  9. #49
    Maximum Bitrate Rundell's Avatar
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    So even if I pass the regulator I still will only get 70W Max. Thats a bummer.
    I think I will just hook the Power Supply up directly and have a switch to turn on the computer. (I already have an extra fog light swicth so I can make it look like the switch belongs)

    I have had my Forester for a year now, actually its my first car. Have never had any problems with it. Main reason I got it was I need the space for my buisness and needed good gas milage. So far its been great. Would love a WRX but need the space so hopefully my next car will be the XT.

  10. #50
    Constant Bitrate STI_FFY's Avatar
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    Quote Originally Posted by Rundell
    So even if I pass the regulator I still will only get 70W Max. Thats a bummer.
    I think I will just hook the Power Supply up directly and have a switch to turn on the computer. (I already have an extra fog light swicth so I can make it look like the switch belongs)
    If you really need more power envelope than the regulator can provide, I would suggest you use the ITPS regulator - but take its output to drive a relay that switches your motherboard's DC-DC supply onto the car's battery.

    This way the ITPS still controls everything, your mobo's DCPS can draw up to the limit of the relay's contacts (size them as large as you need), and the regulated 12V from the ITPS can also be used to power your LCD so it does not change brightness with throttle.

    You won't be using but a fraction of the ITPS regulator's capacity so cooling it should not be a big concern.

    Your only area of potential concern will be when the car's voltage drops below what's required for any of the 12V loads, and how they might react under these conditions. If it's just fans and the LCD you might be OK.
    SeeYa! -Jim-

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