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Thread: Could, Would, Should this work??

  1. #1
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    Lightbulb Could, Would, Should this work??

    Well, is I use the 6volt-12volt voltage doubler thing on Aarons website, and change the zener diode to a 15volt or so, could I use this for the 12volt rail for my player, using a 7812 regulatoer as well?? And then use a 7805 and a transistor for the 5volt rail?
    The power supply would run on between about 7 and 16 volts...
    would this work???


    [ 07-18-2001: Message edited by: THE_SKINNY_MP3_KID ]

  2. #2
    Retired Admin Aaron Cake's Avatar
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    Cool

    The circuit will not provide enough power to run the 12V rail in a standard PC. You're looking at about 2A or more required. Significantly more is required at startup.
    Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
    Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
    "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

  3. #3
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    Talking

    Not so Aaron, my carputer only draws about 1amp max on the 12volt line, and it is normally below 500ma....
    so, it would work??

  4. #4
    Retired Admin Aaron Cake's Avatar
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    Originally posted by THE_SKINNY_MP3_KID:
    <STRONG>Not so Aaron, my carputer only draws about 1amp max on the 12volt line, and it is normally below 500ma....
    so, it would work??
    </STRONG>
    Sorry, but I can't believe that. It may idle at 1A, but startup surges will be much higher. You can try the circuit, but I can't guarantee that it will work.
    Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
    Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
    "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

  5. #5
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    I will try it.....
    My HD draws 280ma 12v MAX
    My Mobo draws I don't know....
    Three cards??? Dunno either....

  6. #6
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    Yeah, I forgot, 4 fans... not much either....


  7. #7
    Retired Admin Aaron Cake's Avatar
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    Cool

    Sigh. I'm guessing that your HD draws about 10A for a split second to start up. 280mA is the running idle current. The motherboard pulls probably 2A or more on the 12V rail, and around 8A at startup. It won't work. You've been warned three times, so don't complain to me when you spend $25 and several hours assembly for nothing.

    For the amount of money and time you spend on this, you are just better off buying an Arise DC-DC converte for $79. It's usually cheaper to buy than it is to build.
    Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
    Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
    "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

  8. #8
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    Cool

    lol...
    For the amount of money and time you spend on this, you are just better off buying an Arise DC-DC converte for $79. It's usually cheaper to buy than it is to build.
    Very true....I keep telling ppl this and they dont want to cough up $79. I guess they WILL never learn.
    abcd-1
    Author of CobraI,II,III and now CobraIV.
    You can contact me on AOL instant messenger....nick is cenwesi or cenwesi3

  9. #9
    Constant Bitrate
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    I think using linear regulators for a PSU is a lost cause. They can't handle the current and generate too much heat. Aaron is right about the large switch on surge current drawn by hard disks. If you don't believe him(or me) look on the seagate website. They have datasheets for their drives which show the current drawn over time as the hard disk spins up. I can't use some full sized hard drives(particularly new models with high rotational speeds) in my player because my DC-DC converter is only 40 watts(I have a laptop hard disk).

    I noticed you live in Aus(as do I) which makes sourcing things from OS an expensive exercise. A good source of DC-DC converters is old 286 laptops(soured mine from one)... and they can be had for less than $79(US or $160AU + Postage + Insurance) if you can find one at the markets. :P

  10. #10
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    Is that true? Do laptop psu's output all the right voltages? and they can run on 14-8 volts? dont need steady 12v?

    would one of these be enough to power a P133, network, soundcard, video card, hdd, no cdrom etc.??

    Cheers!
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