Dumb question. i'm a newbie but need help!

Discussion in 'The Projects Forum' started by paldep, Mar 3, 2016.

  1. paldep

    Thread Starter Member

    Mar 3, 2016
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    I bought a
     
    Last edited: May 13, 2016
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    The preamp has a 5.5 volt max VCC and I believe the datasheet said 2.4 volt minimum.
    If your power amp needs higher voltage you will have to add a 5 volt regulator.
    As for connection you simply add two wires to the preamp output and plug both into your stereo power amp.
     
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  3. wayneh

    Expert

    Sep 9, 2010
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    What battery would you like to use? 3 AAs in series would work, 4 if you use rechargeable Ni-cads. A single Li-ion battery (3.7V nominal) would probably work, but as it discharges your power amp might not be happy (data sheet says 3.6V minimum). A sealed lead-acid (SLA) at 4.5V would work. There are lots of options since your two devices overlap in the 3.6-5V range.
     
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  4. wayneh

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    Two li-ion in parallel at 3.7V? Is that a commercial pack or your own arrangement? The cells need to be (and will be) closely matched in a commercial battery pack. Otherwise it's not such a good idea to put them in parallel.

    You may not be able to use the full capacity of the Li-ion batteries, since they have ~40% capacity remaining when they hit the minimum needed by your power amp.

    And your drawing seems correct for the power. Can't comment on the mic but it looks reasonable.
     
  5. paldep

    Thread Starter Member

    Mar 3, 2016
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    Can you suggest me a battery For a portable device with this environment?Thanks
     
  6. wayneh

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    "This environment"? What environment do you mean?
     
  7. paldep

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    Mar 3, 2016
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    I mean this two circuits. Sorry. Bad English.
     
  8. Dodgydave

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    What voltage do you need, and how big or small does the battery need to be, how about 18650 batteries?
     
  9. wayneh

    Expert

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    He needs something in that range. No idea of any other criteria such as size, capacity, cost, weight, rechargeability, whatever.
     
  10. paldep

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    Mar 3, 2016
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    I need a battery such as old Nokia bl 5c. I saw a Project that use pam8403 Board with the same battery. I dont know if i can Connect two batteries of the same size. I dont know if it's safe.

    I dont know in How much time it will discharge.
     
    Last edited by a moderator: Mar 4, 2016
  11. Dodgydave

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    Discharge time depends on how much current is drawn from the battery, a Nokia battey is approx 850maH, so you can use any combination of current that will give you 850maH

    Example 1mA for 850hours
    10mA for 85hours
    OR. 100mA for 8.5hours
     
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  12. paldep

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    Mar 3, 2016
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    Thanks! Simeone can help me with the circuit? I posted an image. Is it right?
     
  13. Dodgydave

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    Your circuit is ok,but the amplifier needs more voltage to work correctly, you may find your amplifier doesn't give much volume at 3.7v.
     
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  14. paldep

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    Mar 3, 2016
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    Good! I'm happy to hear that. I'll add a 5 volt regulator!
     
  15. Kermit2

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    Run two 3.7 volt batteries in series for 7.2 volts then add the 5 volt regulator. You can get more of the energy out of the batteries this way. Use a low drop out regulator. They will be called LDO voltage regulators
     
  16. paldep

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    Mar 3, 2016
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    If i want to charge the batteries in Series? It's possible?
     
  17. wayneh

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    Do you have a separate, dedicated charger for that battery type, or do you want to build something? If you want to build, I would suggest you choose 4 AA Ni-cad batteries or even the SLA I mentioned earlier. They are much easier to charge properly with simple, do-it-yourself circuits. For a beginner such as yourself, a Li-ion charger is a "big" project that requires a special IC designed for charging Li-ion cells.
     
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