24V Battery to +-5V DC Converter

Discussion in 'General Electronics Chat' started by Stryker, Mar 26, 2009.

  1. Stryker

    Thread Starter New Member

    Mar 26, 2009
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    [​IMG]
    I don't know how to get the voltages +5V and -5V from a 24V battery.
    A DC converter is needed for the minus rail, isn't it?
    I'm a newbie, Please help! what can be put instead of the '???' block?
     
    Last edited: Mar 26, 2009
  2. bertus

    Administrator

    Apr 5, 2008
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  3. Stryker

    Thread Starter New Member

    Mar 26, 2009
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    Thank you for fast response,

    But I'm looking for a simple circuit using ordinary components. Any circuit ?
     
    Last edited: Mar 26, 2009
  4. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    With the 78L05 (or 7805) you will loose almost 80 % power, that is transferred into heat.
    With the circuit I pointed at you will loose 10-15 %.

    Greetings,
    Bertus
     
  5. Stryker

    Thread Starter New Member

    Mar 26, 2009
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    Hello Bertus, my needed current is less than 20mA. so a 78L05 will be ok. I connected one to 24V battery, it heated up soon!

    Another problem is that I'm planning on using an ICL7660 to get the -5V supply. but its maximum input voltage is 10V. How do I connect it to the battery?

    Regards!
    Stryker
     
    Last edited: Mar 26, 2009
  6. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    For your heat problem you can take a LM7805 in a TO220 housing.
    That has a metal plate to spread the heat.
    ( you can enlarge the plate for better heat spreading by mounting it to the a copper or aluminium plate).
    For the ICL7660 : take the LM7805 output as input for the ICL7660 (this is the 5 Volts).

    Greetings,
    Bertus
     
  7. Stryker

    Thread Starter New Member

    Mar 26, 2009
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    OK, Thank you very much!
     
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