battery Charger for 12v

Discussion in 'General Electronics Chat' started by indika perera, Feb 22, 2015.

  1. indika perera

    Thread Starter Member

    Mar 7, 2013
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    dear all,

    i have created following circuit as a 12v battery charger but its output voltage is higher(some what 25v) than the expected voltage which is around 14.5V . So any body please explain is their any faults of this circuit and how to correct it..

    Big thanks.

    indi
     
  2. MrChips

    Moderator

    Oct 2, 2009
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  3. indika perera

    Thread Starter Member

    Mar 7, 2013
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    thx 4 the reply MrChips..so do u think is their any prob?
     
  4. ScottWang

    Moderator

    Aug 23, 2012
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    1. Check the pins connections of LM350.
    2. Re-check all the wires connections.
    3. Check Q2, Q1, do they work?
    4. Does the D2 LED lighting, does c voltage of Q2 close to gnd?
     
  5. indika perera

    Thread Starter Member

    Mar 7, 2013
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    thx..scottwang...yes i have checked several times..my doubt is that lm350 voltage regulator require proper resistance combination through it pins to necessary drop of voltage.. another thing is that variable resistant is set to adjest voltage but in my case it is no longer affect anything to the output..
     
  6. ScottWang

    Moderator

    Aug 23, 2012
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    How is the point 4 that I mentioned, did you measure it, and how is the LED?
     
  7. indika perera

    Thread Starter Member

    Mar 7, 2013
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    led blinks..but once i checked the battery terminal from the multi meter the led again blinks..that means i does not has some resistance..me be it blinks for higher voltage may be 25v fortunately not burn out.
     
  8. ScottWang

    Moderator

    Aug 23, 2012
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    How is the input voltage, Vdc, DC pulse, how high?
    What are you trying to charge the battery, Vdc, DC pulse?
     
  9. indika perera

    Thread Starter Member

    Mar 7, 2013
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    input 24v dc output expected 14.5v but output was 25v..that the issue..
     
  10. ScottWang

    Moderator

    Aug 23, 2012
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    Where is the Vin dc came from?
    It looks like the filtering has some problems, do you have O'scope to measure the Vin?
     
  11. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Measure the voltage at the base and emitter of the BD140.
     
  12. indika perera

    Thread Starter Member

    Mar 7, 2013
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    dear scottwang dc input will be given from a 3A transformer with 4 half way rectifiers..dc input has no issue it wil around 17v-24v range NOT above that..
    need some help
    no i havn't O'scope
    thx
    indi
     
  13. indika perera

    Thread Starter Member

    Mar 7, 2013
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    Thx for reply..so what to do with measuring above voltage..i'm not expert in electronics..any clarification please
     
  14. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    Short out the C/E of the bd140, what voltage is at the output, is the led on?
     
  15. indika perera

    Thread Starter Member

    Mar 7, 2013
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    thx..dodgy... i am actually away with it just kept it in a box..and trying to figure out the prob with this forum..you sure is not there any harm for bd140 while shorting..ok i will try..thx
     
  16. indika perera

    Thread Starter Member

    Mar 7, 2013
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    i search that lm750 module on ISIS simulating software but coould not found..plz anybody know good software with huge database for circuit simulating..
    thx indi
     
  17. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    lm350 is the one in your circuit???
     
  18. indika perera

    Thread Starter Member

    Mar 7, 2013
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    yep..
     
  19. indika perera

    Thread Starter Member

    Mar 7, 2013
    30
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    anybody plz help me..
     
  20. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Do you know which pins on the BD140 are the base and emitter?
     
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