+ and - 5v power supply

Discussion in 'Homework Help' started by kelun1, Mar 25, 2012.

  1. kelun1

    Thread Starter New Member

    Mar 25, 2012
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    Hi guys!

    I need help on the following issues.

    I'm trying to build a dual 5v power supply for one of my application in my hardware. and below are the list of the item i have in my hand:

    LM7805
    LM7905
    9v DC battery as input power for my regulator

    Im able to get the 5v regulated power out from 7805 with the negative end of the power supply as ground. but i cant seems to get 7905 to work properly. and i know that both output should have a common ground. can anyone teach me how should i build this?

    Thanks a million for reading this guys! and the help too! =)

    Kelun
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
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    kelun1 likes this.
  3. kelun1

    Thread Starter New Member

    Mar 25, 2012
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  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    Remove the center tap transformer and the rectifier (B1) of course. And hook up your batteries. You do know that a 9 volt battery will not have much energy and wear out quite fast in a setting like this. But to only demonstrate something it should be OK. Just be sure to have fresh batteries then you demonstrate it for your tutor ;)
     
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  5. kelun1

    Thread Starter New Member

    Mar 25, 2012
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    oh! thanks for highlighting about the rectifier! almost forgotten about it. so i will just remove that 2 and connect straight to the mentioned circuit.

    at first i was so worried that i can't get this out or something and worried that i will fail my final year project. really thanks alot man! u light up my days =)

    Kelun
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    You are on the correct track...
     
  7. kelun1

    Thread Starter New Member

    Mar 25, 2012
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    Thank again! =)
     
  8. t06afre

    AAC Fanatic!

    May 11, 2009
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    One thing. Read the both the datasheet regarding recommendations for the caps used in the setup. And do not forget to mention this in your report.
     
  9. n1ist

    Active Member

    Mar 8, 2009
    171
    16
    Don't forget that the pinout is different between 78xx and 79xx regulators; the tab on the 79xx isn't ground.
     
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