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who knows about ac to dc conversions

Discussion in 'The Lounge' started by mudhog, Mar 7, 2006.

  1. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    what id like to do is find something that will power an automotive stereo amp. can i take an old 300wat power supply from a pc and us it to power an automotive stereo amp?
     
  2. 1979jimmy350

    1979jimmy350 1/2 ton status

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    you can buy power inverters to do that, i would think that a computer power supply would not have enough amp out put to do it
     
  3. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Car battery and a charger to keep it topped off . I doubt any inverter under 100 bucks would like an amp on it .
     
  4. newyorkin

    newyorkin 1 ton status

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    If you were minded to build something out of radio shack parts, you could easily and cheaply buy a 12 volt transformer, a rectifier bridge, and wire your 12 volt device into it.
    But the current draw (amperage) is important, you may end up needing a big prebuilt power supply to properly supply the current necessary.

    You should be able to find some stuff on google, quick search tossed out this:
    http://www.reconnsworld.com/power_12vpowersupp.html
     
  5. Jagged

    Jagged 1 ton status

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    What size fuse do you run your stereo system through?


    Okay then, I say it will work. Remember though, "12 volts" in vehicles is 13.8

    Are we talking peak output or RMS (aka average output)
     
  6. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    If your running a 300 watt amp you need to have 30 amps of power to supply it at peak output. Divide wattage output by 10 and that will tell how much input power it will need. Some pc power supplies might be able to deliver that much power, don't know what kind of duty cycle they would have. I think it would be cheaper to go pawn shopping for a cheap used amp than to rig a power supply up.
    George
     
  7. Seventy4Blazer

    Seventy4Blazer 3/4 ton status

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    i had one in my garage... blaupunk head and pioneer amp, 200w on a car battery. ran two 8's ad 4 6x9's with no problems. all i powered everything with was a car battery and my charger. i put the battery and charger on the side of the house and ran the power wires into the garage into the deck just on the other side of the wall. this way hydrogen stayed OUTSIDE and i had tunes. i got EVERYTHING from the junk yard when i worked there. was nice honestly. then i moved out of the house 2 weeks later....
     
  8. justinf

    justinf 1/2 ton status

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    Just curious, why are you dividing by 10? 300W is the output power of the amp, the input power would just be the 300W output, plus the power losses in the amp itself.

    The ouput current is 25 amps (300/12), so the input power may very well be 360W (30 amps), but this would vary depending on the amplifier used.

    The PC power supply should give list its output power on the namplate. Take a look at one and see what it is rated for. The amplifier should also have a namplate listing the nominal voltage, and the input and output power (or it may just list a full load current, multiply this by 12 volts to get the input power).
     
  9. smalltruckbigcid

    smalltruckbigcid 1/2 ton status

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    My bad... your right on the 12. Its divide by the voltage. :doah:Ive got a new Antec true 480 watt power supply and it lists the 12v max as 28a. But thats running on 16ga wire. That will get hot and and have power loss.

    To defend my original number though I got told years ago by some engineer at Tripp-lite to divide by 10 because watts divided by 10 will tell you how many amps it "should" pull in a 12 volt circuit.

    Either way that circuit will want a 10ga wire to run at full output, and heavier if the wire has a longer run to the amp. In my semi I've got 2 amps for the stereo and the power wires are 2ga welding cable (800watts for the 2 subs and 600 watts for the 4-6x9's)
    George
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    battery charger...

    The cheapest and most reliable source of 12V power is an ordinary battery charger,and a car battery(it acts as a "filter" to reduce hum from the transformer)..I used a deep cycle marine battery and a charger in my shop with a 300 watt amp I saved from my Chevelle wagon when I sold it,and used a woofer box with two 15" speakers on it..worked great for many years...

    I'd say building your own is possible,but I doubt it'll cost less or work any better than a battery charger would..its not cheap to buy a transformer,rectifiers,that will put out the 30 amps you need..hit a flea market or yard sale for a cheap charger..a small computer fan to help cool it isn't a bad idea either..:crazy:
     

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