Which battery to use?

Discussion in 'Power Electronics' started by clickman, Dec 13, 2016.

  1. clickman

    Thread Starter New Member

    Dec 9, 2016
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    Hi everyone. I'm involved in a personal learning Project of making a simple audio amp for my Smartphone. I'm using a LF351n that requires a V+ and V- and i've used the virtual ground technique for achieving the voltajes with 2 9V batteries. The thing is that i don't seem to get a proper performance out of the circuit, so i believe the power supply could be the problem.

    My question is what else could i use to power my circuit? I would like to keep it portable, so AC isn't an option.

    Thanks everyone in advance.
     
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Post your circuit, and it probably would be better to use higher current batteries.
     
  3. #12

    Expert

    Nov 30, 2010
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    The LF351 has a pretty weak output current. If that's all you have, you can barely light an LED, let alone a speaker.
     
  4. clickman

    Thread Starter New Member

    Dec 9, 2016
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    Wow, i didn't realized that was happening. Should I go for a LM 368?
     
  5. clickman

    Thread Starter New Member

    Dec 9, 2016
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    This is a very simplified schematic:
    amp2.JPG
     
  6. crutschow

    Expert

    Mar 14, 2008
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    An LM368 is a voltage reference.
    You need an audio amp.
     
  7. clickman

    Thread Starter New Member

    Dec 9, 2016
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    My mistake is that somewhere I saw an audio amp using a 368. What would you suggest me?
     
  8. #12

    Expert

    Nov 30, 2010
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    How about an LM386?
     
  9. clickman

    Thread Starter New Member

    Dec 9, 2016
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    386 yes! but does it need a lot of power? i would like to use portable power.
     
  10. #12

    Expert

    Nov 30, 2010
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    The chip doesn't use up power compared to how much the speaker does.
    This is like asking if the steering wheel gets good gas mileage.
     
    Robert Murphy likes this.
  11. clickman

    Thread Starter New Member

    Dec 9, 2016
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    Great analogy, so this means that maybe i'm too ambitious with trying to drive a speaker with batteries or any other portable power?
     
  12. crutschow

    Expert

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    For maximum battery life you want a Class D (switching) audio amp such as this.
    It can be powered from three AA or AAA batteries in series.
     
    cmartinez and #12 like this.
  13. #12

    Expert

    Nov 30, 2010
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    Millions of, "boom boxes" have been sold. Are you too ambitious to try to do something that has been done so many times before?
     
  14. clickman

    Thread Starter New Member

    Dec 9, 2016
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    I get it, the thing is that i don't know how to properly do it. my approch is flawed.
     
  15. clickman

    Thread Starter New Member

    Dec 9, 2016
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    Battery life is very important, but will output be sacrificed?
     
  16. #12

    Expert

    Nov 30, 2010
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    Are you kidding? Everything we say, you ask if it makes something else not work.
    Sure, we sit here and give bad suggestions so you will fail, no matter which one you believe.
    Is that what you think?
     
  17. clickman

    Thread Starter New Member

    Dec 9, 2016
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    No you misunderstood me. I'm new so you should know that i have questions and that I don't know anything, I'm learning and that's normal and also i don't believe that people he want to intentionally misguide others.

    Maybe I should leave.
     
  18. crutschow

    Expert

    Mar 14, 2008
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    Sacrificed how?
    Did you look at the data sheet to see if it meets your requirements (which you haven't stated)?
     
    Last edited: Dec 13, 2016
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