+/- 5v Regulated Power Supply

Discussion in 'The Projects Forum' started by wellyboot, Jul 17, 2008.

  1. wellyboot

    Thread Starter Member

    Jun 1, 2005
    16
    0
    Hi

    Im looking for a simple regulated split rail power supply (+5v GND -5v) from a 12-15v DC supply
    Its for a low current application <100mA, but the +5v rail will supply more components (ie Pic chip/real time clock/LCD ect) so will have more current flow, the -5v supply only feeding the negative supply rail on a op-amp and a sensor.

    I did see a diagram a while back that used a 7805 and 7905 5v regulator ICs, but cant remember where it is!

    Thanks
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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  3. Wendy

    Moderator

    Mar 24, 2008
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    To do what you're wanting the original power supply will have to be floating though, no ground. This is because you want to establish a ground after the fact.
     
  4. weije1986

    Member

    Apr 19, 2008
    14
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    search the datashet of LM7805 . Inside that datasheet should have information if i not mistaken :)
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    I have pinouts for several popular chips in my PaintCAD, which you can download off my blog.
     
  6. Tahmid

    Active Member

    Jul 2, 2008
    344
    25
    Hi,
    Wellyboot,
    This is a common +/- 5v 0.75A power supply. It is cheap and easy to make, but safe to use and very reliable. Hope it will fulfill your requirement. Instead of 100mA, I have given a circuit with 0.75A. If you require less than 100mA, you can use the 78L05 and 79L05 instead of the 7805 and 7905 shown in the schematic. 7805 and 7905 are found in TO220 package and 78L05 and 79L05 are found in TO92 package.


    _____________________________________________________________________________

    The strongest man in the world is one, who stands alone for achieving something good.
    পৃথিবীতে সেই সবচেয়ে শক্তিশালী ব্যক্তি, যে ভাল কিছু অর্জনের জন্য একাই নিরন্তর চেষ্টা চালিয়ে যায়।
     
  7. Tahmid

    Active Member

    Jul 2, 2008
    344
    25
    Hi,
    The earlier attachment was a circuit from mains. The one attached here is from 12-15v dc source. It is shown for 1A, but if you require 100mA, you can use 1W zeners.




    __________________________________________________ ____________________________________

    The strongest man in the world is one, who stands alone for achieving something good.
    পৃথিবীতে সেই সবচেয়ে শক্তিশালী ব্যক্তি, যে ভাল কিছু অর্জনের জন্য একাই নিরন্তর চেষ্টা চালিয়ে যায়।
     
  8. wellyboot

    Thread Starter Member

    Jun 1, 2005
    16
    0
    Hi Guys

    Thanks very much for the replys so far, havnt had chance to try any of them yet, but will be soon

    Thanks again

    Dave
     
  9. Wendy

    Moderator

    Mar 24, 2008
    20,765
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    It can be iffy, you have to load them down some, but computer power supplies have all those voltages. Being switchers they also have a lot of ripple on them.
     
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