9volt Battery Charger questions

Discussion in 'The Projects Forum' started by samsam_91, Dec 7, 2012.

  1. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    Hello Everyone >>

    I need to make a charger for 9 volt battery , have a circuit but want some help about resistor of regulator ..

    <snip>

    my questions on :
    1) R1 ,R2 ,R3 values to make a regulator work and also with transistor to make a LED On if it still charging and Off if it fully charging if the battery capacity is 175 NiMH

    2) If I'll use lm317 what changes in the circuit ?

    and finally please write the equations you have used to find Resistors values to apply it if I have changes ..

    thanks :)
     
    Last edited by a moderator: Dec 7, 2012
  2. wayneh

    Expert

    Sep 9, 2010
    12,154
    3,061
    I'd move D2 to protect the regulator against the output (the battery voltage) being higher than the input (eg. if the AC is unplugged).

    I believe your rectifier DC connections are backwards also. Still drinking my coffee, so I might be confused.

    I'm sure you'll be getting answers to your other questions.
     
  3. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    5,003
    745
    Either you have forgot the transformer for your power supply, if not i believe this is a transformer-less psu and is therefore forbidden !!!!
     
  4. wayneh

    Expert

    Sep 9, 2010
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    Dodgydave is a bit more awake and has correctly noticed a very critical flaw! That 7809 would pop like a balloon if it saw 300V.
     
  5. Georacer

    Moderator

    Nov 25, 2009
    5,142
    1,266
    As Dodgydave says, non-isolated circuits connected to the mains are not allowed in AAC. Please update your schematic with an isolation transformer and a fuse, even if its ratio is 1:1.

    Thank you for your understanding,
    Georacer
     
  6. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    the ac source is already means transformer but I forget to say this :) ... 12-0-12 transformer :)
     
  7. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    [​IMG]

    Like this with diode for protection ?
     
  8. wayneh

    Expert

    Sep 9, 2010
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    Yes, although I see no use for D2. And your rectifier is still backwards.
     
  9. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
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    The bridge rectifier terminals 1/4 are the wrong way, also the voltage source is 220v ac NO Transformer!!!...
     
  10. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    okay what about moving the D2 before the battery "to block any backwards" .. ?
     
  11. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    Unfortunately I dont have a good sim to make a circuit it's not contain a transformer and also the bridge not have "AC" and "positive or negative" pins .. but anyway I will do it true on board dont worry about this :)
     
  12. wayneh

    Expert

    Sep 9, 2010
    12,154
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    The diodes in the rectifier, once correctly oriented, will perform this function and you don't need or want another one. It would just waste power.
     
  13. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    what about now ?
    D3 to stop backward from battery ..

    [​IMG]
     
  14. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    You need a a linear regulator with remote sensing so you can take out the voltage drop of D3.
     
  15. samsam_91

    Thread Starter New Member

    Dec 1, 2012
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    such as LM317 Regulator .. ?
     
  16. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    samsam_91 likes this.
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