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Thread: My low cost, easy to build power supply...

  1. #1
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    Post My low cost, easy to build power supply...

    I wanted a DC-DC power supply able to power my P100 in the car, I didn't need it to be able to power it while starting the car, only while it was running...
    I had a budget of less than $5 Australian, and cane up with this idea...
    it works quite well, and costs next to nothing to make..


    I am using low dropout linear regulators(1084) for the 5 and 12 volts. They are both rated at 5amps... For the negitive voltage I used max774 and max 775, these can supply 1amp at -5volts with a 3-16volt input and 400ma at 12volt with a 3-16volt input...

    (all of the above component are available as free samples)

    The negitive voltage regulators need an external mosfet, (which I had to buy) and the other component I had to buy was the 4049 for the power good signal, All the other caps and resistors I already had.

    The whole thing is housed in a standard AT power supply case from a dead power supply, and the heatsink used is a PII one that I bought for fans for my othe player..

    All up, the power supply took less than one day to build, and can quite happily power my P100, HD and CDrom from the cars battery while the car is running...

    Yeah, I forgot to add in the point that the circuit board I used also cost nothing, as I didn't use a circuit board as such, I used a piece of MDF wood cut to size, and I just drilled the holes where I needed then, and wired on the bottom as you would with standard matrix board...

    Its really simple, and really cheap, and really easy to make...

    if you don't care about efficiency or size, and are worried about cost, I suggest you try making one of these supplies, I wall post some pictures soon as possible..

  2. #2
    FLAC
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    Post

    interesting....post a pic let us all see.
    abcd-1
    Author of CobraI,II,III and now CobraIV.
    You can contact me on AOL instant messenger....nick is cenwesi or cenwesi3

  3. #3
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    Sorry, Don't have a picture yet, will get one as soon as possibly, maybe tomorrow..

  4. #4
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    Okay, I will have to be honest with you, this supply doesn't exist yet, it half exists, I havn't been able to locate the mosfets, and I haven't bought the 4049 yet, but It will be done in the next few days MAX, thats if I can find the mosfets..

    So far though, I have spent nothing on it, the 4049 will cost $1.15, and I HOPE he mosfets aren't too expensive..

    [ 12-03-2001: Message edited by: SkinnyBoy ]

  5. #5
    Raw Wave Rob Withey's Avatar
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    Post

    Linear regulators for the 5V line are not such a good idea, as you'll find when you build the thing. 5V at 5A will have more power dissipated than it actually delivers to the computer. 9V voltage drop (with engine running) times 5A is about 45W...!


    Rob
    Old Systems retired due to new car
    New system at design/prototype stage on BeagleBoard.

  6. #6
    Retired Admin Aaron Cake's Avatar
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    Originally posted by Rob Withey:
    <STRONG>Linear regulators for the 5V line are not such a good idea, as you'll find when you build the thing. 5V at 5A will have more power dissipated than it actually delivers to the computer. 9V voltage drop (with engine running) times 5A is about 45W...!
    </STRONG>
    We've been through this before with him, he didn't listen. He will find out soon enough though.
    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."

  7. #7
    FLAC
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    i like this thread! making a claim to fame, then confessing that u aint made it anyway? whats the deal there? just a dead thread im afraid.


    and yes we did go over this, like Aaron said... sheesh that thread got heated!!
    Project - GAME OVER :(

  8. #8
    Maximum Bitrate
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    HAHAHA

    What a bull**** Artist!
    Fosgate

    System Comp V3 - In progress.
    Low power MB with C7 CPU, DC-DC PSU, car ECU link, USB TV, GPS, 7" TFT, Wireless, Voice.

  9. #9
    FLAC
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    moahdib's Avatar
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    LOL i love the way Skinnyboy brings some humor to this board from time to time.
    04 Acura TL w/ core2duo 2ghz laptop w/ 1gb RAM on a docking station.

    Fast car, fast PC. ;)

    http://www.arcdesigns.net/carpc/

    My TL CarPC ver2

    FSR Flash Skin w/ moving weather maps

  10. #10
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    NO!!!!!!
    I have made the positive 12volt and 5volt section, and the supply spins up a HD and the regulators don't even get warm...
    I have now finished the power good part of the circuit, and am moving onto the negitive voltages asap..
    I am only using linear regulators because it is simpler, and at no time will I be drawing 5volts at 5amps from it..
    It should work out fine, I will post some pictures of the power supply (minus the negitive parts) tonight...
    STOP COMPLAINING!!!!!!!
    you don't have to make this supply, I was just telling you that I was, and I will post how successful it was when I have finished..
    okay??

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