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Thread: 12v supply

  1. #1
    Newbie
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    Apr 2000
    Location
    Rockhampton, Queensland, Australia
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    18

    Post 12v supply

    Gudday,
    well this may be a stupid question but how do we get a good high power 12v line from a car. All the other voltages are easy...I would like to develop from 5 to 10 amps too. Getting 12v at first seemed easy, till you consider that a car sitting still may drop down to as low as 11 volts. Any help would be ...well...a help )
    Cheers,
    Fabian

  2. #2
    Maximum Bitrate gizmomkr's Avatar
    Join Date
    Dec 2000
    Location
    Smyrna, Ga, USA
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    778

    Post

    a simple voltage regulator will do. Thats a pretty high amperage. I would recomend an automotive / batery charger regulator. they are easy to find ( http://www.jcwhitney.com or http://www.crutchfield.com ) and they run at high amperages.
    Gizmo-
    Techonlogy on Wheels
    http://www.hjnetworks.com/car

  3. #3
    Low Bitrate
    Join Date
    Feb 2001
    Location
    Kuutinkylä, FINLAND
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    Post

    I was thinking that too. I don't have money to buy any regs & here are only 7812 regs = poor

    I think I'll build some hacker-coil to produce +/- 15VDC
    WINAMPCAR
    Project almost ready

  4. #4
    Newbie
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    Apr 2000
    Location
    Rockhampton, Queensland, Australia
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    Post

    Gudday,
    Well I could use a simple regulator but what happens if it drops below 12v? This is the crus of my problem...gaining 12v from 12v or above is easy, even at high amps but below is more difficult...Ohhh well I will just keep looking. GThis is the only thing holding me back now
    Cheers,
    Fabian

  5. #5
    Newbie
    Join Date
    Mar 2001
    Posts
    4

    Post

    you could try adding a small 12v motorcycle battery to your setup, with something that would only charge it when the car was on. this would provide the double benefit of giving you a constant 12v supply, and letting you run the system with the engine off.

  6. #6
    Newbie
    Join Date
    Apr 2001
    Posts
    6

    Wink

    I have had the same problem but before the solutions a short explination.

    You need a clean 12V rail for a computer the accessory socket cigarette lighter gives out 12V if you run this through a regulator you get on average get a 2V drop giving you 10V no good at all.
    The Alternator gives 14.8V (I think) when the car is running so it can go through the regulator drop the 2V and still give you a clean 12V. But you carn't listen to MP3's with the engine off. Also you have to get the 14.8v to your power supply through the fire wall of your car. Feel like drilling a hole or sharing one with something else? It's a barstard isn't it.

    The answers
    A Inverter this is what I eventually did plug it into your cigg socket and run the PC no problems. $100 that's OZ dollars. I got the biggest one that the cigg socket fuse could take and it runs my AT 200MMX and drive fine.

    Building a DC-DC converter you have probabally seen some circuit diagrams on the web in different places "sproggy" has one but there are others most rely on Maxim chips to drive them these are hard to get in OZ and can cost up to $30 when you can get hold of them try Rockby electronics or Farnell both have sites in OZ. The other way is to get a Jaycar Electronics catalogue and take a look at the circuits in the back voltage and amperage booster circuits built out of common cheap components. I hate blowing $30 regs.
    The best way to test a circuit is to get a "bread board" from Jaycar and actually plug it all in and test the output.
    Then;
    Draw the circuit.
    Etch the circuit board.
    Solder the board.
    Test the board.
    Install the board.

    I don't want to put you off but unless you can already do all the above it could be a long time before you get to listen to any MP3's in your car.

    Some other answers you might like to know being from OZ

    Getting the signal to the speakers

    Jaycar have a kit called a minimitter Small Fm stero transmitter $30 tune into the MP3 player like it was a radio station. You need to solder it. It works but Im not 100% happy with it

    Casette adapter from Tandy $30 this means your casette motor will run all the time.
    I had an old one I tryed didn't work very well.

    Eurovox OZ made car audio there lowest model has a jack on the front for a portable Cd player and its only $100 with 4 speakers bargan!!!
    check out the site you can buy on line.

    Or cut into your speaker wire with a DP DF toggle switch.

    LCD displays try WWW.microzed.com.au $5 to ship get it the next day. Cheaper than any of my local Electronic stores don't be put off by the basic web page call and ask he's a nice guy. He has a lot of other stuff to for PIC and STAMP if you are building a circuit and carn't find a part give him a try I have got 12V LED's and 10k Thermistors from him.

    If you want advice from a OZ site try www.overclockers.com.au
    local prices and the best way to mod cases etc.

    Hope I have saved you some time and not put you off.

    I get a bit carried away

    good luck

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