help to design;two DC power source as one

Discussion in 'The Projects Forum' started by apurvmj, Sep 28, 2012.

  1. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    Hi there all,
    I'm a newbie in circuits, I have unique requirement to have 12v, 100w DC power supply with 3v & 9v batteries, but without having them in series. I tried transistors but couldn't figured it out.
    Will some one pls help me.
    Thanks in advance.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,003
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    What type of 3V and 9V batteries are you planning on drawing 100W?

    And why can't they be in series?
     
  3. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    those box like rechargable batteries
    & about non series connection just to understand 'Op amp' as experiment.
    could someone reduce Op amp for this purpose. i guess there are aprrox. 20 transistors in op amp.
     
  4. wayneh

    Expert

    Sep 9, 2010
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    You may be confused about what an op-amp does. It is NOT a way to create power. It is used to CONTROL the power supplied by a source such as a battery or power supply. A small amount of power is lost in the internal operation of the op-amp and by its associated circuit components. With good design, these losses are very small.

    But the fact remains that ALL the power comes directly from the power supply and the op-amp does not increase that, only reduce it.

    Does that help clarify? If not, we are having trouble understanding what you want to do with your op-amp.
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,980
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    12v @100w is 8Amps at least, your not going to get that from small batteries.
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,140
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    Maybe NiCad or NiMH for a few seconds. Go get a SLA Deep Cycle Marine Battery at Wallmart for about $54. Oh and you'll need a charger for it. Wallmart has those too.
     
  7. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    I know that Op-amp doesn't increase the power, what I want is V1+V2. I was thinking sort of component of Op-amp, as Op-amp has few multi-transistors component in side it.

    # Dodgydave
    thanks for concern but these batteries are heavy duty & with series they are just good to supply 100w for half an hour or so.
     
    Last edited: Sep 29, 2012
  8. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Could you tell us the name brand of these powerful 9 volt batteries?

    11 amps output for 30 minutes (=100 watt for 1/2 hour) is one HELLOFA of 9 volt battery. is it the same size as the standard 9 volt like you put in a smoke detector?

    100 watts, ... :)
     
  9. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    no they are big, half the size of car batteries, rechargable.
    btw I'm from India & battery is of local brand.
     
  10. wayneh

    Expert

    Sep 9, 2010
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    I still have no idea what you want to accomplish with the op-amp. How does it relate to getting V1+V2 at 100W?

    Batteries are a source of EMF, electromotive force. In a circuit, you can't get more electromotive force without adding more sources of EMF in series. There are ways to boost voltage. Perhaps you are looking for a boost circuit?
     
  11. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    amen, me neither
     
  12. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    By saying op-amp I doesn't mean it literary. I don't intent to use Op-amp as whole, may be diffrent design of power transistors, inspired from Op-amp. I heard that OP-amp used as summing amplifier. I need any circuit to get 3v+9v=12v, as a power source but you may ignore 100w requirement.
    Hope I make myself clear this time.
     
  13. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Any circuit you make will have to 'ADD' the voltages.

    In other words, the circuit will put the battery voltages 'IN SERIES'.

    The other option is to use a wide range input Boost converter that will produce 12 volts with either 3 volts input or 9 volts input. With this method you only use one battery at a time and not both.


    You decide.
     
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  14. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    thats my purpose; a circuit to put battery voltage in series without putting them in actual regular series.
    if that is not possible,thanks for the information.
     
  15. RamaD

    Active Member

    Dec 4, 2009
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    Still not clear as to what your requirement is.
    The output of the opamp comes from the power supplied to the opamp through its power pins. The current capacity of the output is limited to the opamp's output capacity and not that of what is connected to the inputs (batteries as you intend).
     
  16. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    apurvmj likes this.
  17. apurvmj

    Thread Starter New Member

    Sep 28, 2012
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    thanks for that.
    kindly refer http://www.allaboutcircuits.com/vol_3/chpt_4/7.html in this "Common-base circuit for DC SPICE analysis" graph you can see 'series-aiding effect'. but base-collector loop gets saturated at 1.2v & I want to operate at more than that. So I need something like this?
    What I've observed that when I say something like Op-amp, people stick to Op-amp only. I only mean I want any circuit, simple & made for the purpose, may be inspired from say Op-amp.
    Thanks.
     
    Last edited: Sep 30, 2012
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