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Stereo backpack electrical conversion

Discussion in 'Electronic Design' started by Josh, Mar 10, 2007.

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  1. Josh

    Josh Guest


    I am building a "stereo in a backpack" and need help with converting
    power the easiest and cheapest way i can.
    I found a small amp with 3 speakers hooked up that runs off of ac
    the transformer is converting the household current down to 12volt ac.

    I had an idea of running this setup off of an rc car battery pack -
    which is 9.6 volts

    What do you think? Thanks
  2. And that in turn is converted to DC. What voltage?
  3. Eeyore

    Eeyore Guest

    Rectified 12V AC is a lot more than 9.6 volts but if you don't need that much
    power you don't need the higher voltage.

    I assume you want long battery life ? Check out Class D amplifier chips. They
    are significantly more efficient.

  4. Josh

    Josh Guest

    it is not converted to dc as far as i know.
    the transformer is just changing 120vac household down to 12 volts ac.
  5. Transistors don't run off AC.
  6. Guest

    And the "playing time" is?

    There is probably nothing cheaper than getting a car stereo power amp
    and using 12V. Use a gel cell instead of the rc car battery.

  7. USE FUCKING HEADPHONES, stop polluting my space with your noise

  8. Josh

    Josh Guest

    Excuse me but i never said i was using this in public - im looking for
    help on electricity not on what your enraged opinions are.
  9. Josh

    Josh Guest

    Hi, I am not using a car stereo - it is an ac powered amplifier device
    bassically for a computer. I need to fit this in a backpack that can
    be carried around easily - so the lightest, the better. thanks for
    your help though. Maybe you would know of arechargeable source of ac??
    im just trying to use what i have around my house.
  10. Josh

    Josh Guest

    It is a transformer, not a transistor - i am just trying to run a
    small computer speaker amplifier, off of a rechargeable source of
    energy. Thanks
  11. Josh

    Josh Guest

    That is a good idea - unfortunately i dont have the money to buy/build/
    put together that sort of stuff. I'm just trying to see how i can use
    stuff around the house. Thanks for the suggestion though - i might use
    that idea later on. :)
  12. You don't have a clue. You really can't do what you think you want to.
  13. Homer is asking what DC voltage is actually used inside the amplifier.

    The 12 volt AC will be converted to DC in the power supply section of
    the amplifier. The thought is that it may be easier to produce the
    required DC voltages (and bypass the internal rectifiers) than trying
    to create 12 VAC.

    Peter Bennett, VE7CEI
    peterbb4 (at)
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  14. Josh

    Josh Guest

    I dont understand how that would work when the whole amplifier system
    runs off of AC. The transformer is only stepping down the voltage/
    amperage, it is not converting the current. That is what i am trying
    to do - change the current input from ac to dc source.
  15. Josh

    Josh Guest

    And also - this is not an impossible task. I already know how to do
    this - but it is too expensive, i am looking for the alternative
    methods out there that people may have messed around with before or
    came up with.
  16. Guest

    A car stereo amp can be used as any general purpose amplifier. I try
    to find turn key solutions before designing my own circuits.

    I don't see why you would want an AC powered device if you are trying
    to be portable. With an inverter, the quality of the AC is terrible. A
    cheap car amp would do the trick.

    To really get an intelligent answer, you need to be very specific.
    What is the play time? What power output? THD?
  17. Josh

    Josh Guest

    you have a good point about the quality. I suppose a car amp would be
    very cost effective, then im not stuck with a cheap pc amp, and
    and also i can use better quality speakers that i have laying around.
    Thanks for the great idea!!!!

    That is all the help i need
  18. Eeyore

    Eeyore Guest

    There is no such thing.

    Electronics runs on DC. Your amplifier contains a rectifier to convert the ac
    input to dc. Run the amplifier on dc and you don't need the rectifier.

  19. Eeyore

    Eeyore Guest

    He knows. You simply missed the point he was making.

    You should really be asking in the basics group in that case, not design. This
    isn't a design issue.

  20. Josh

    Josh Guest

    You know what - it is not posssible to just bypass the rectifier and
    hook in a dc source of power - i correctly wired it all and fried my
    battery. You guys just don't understand what i was trying to tell you
    - yes i understand electronics run off of dc - so why didnt you just
    tell me where to hook in the dc supply on the circuit board? i dont
    know the brand of it and dont know the power. it just is configured in
    a cube shaped chair and has 2 speakers and 1 subwoofer hard wired to
    the circuit board with an on/off switch, volume knob, and bass knob.
    And this can be under the design section - but no one wants to fully
    read and understand the posts one step at a time

    Don't bother replying because im done here - thanks for the people who
    actually tried to understand and did help.
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