+V, -V supply from 9V battery to power LM741

Discussion in 'Homework Help' started by Slik_Willie, Mar 14, 2010.

  1. Slik_Willie

    Thread Starter New Member

    Mar 14, 2010
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    I am designing a circuit that include a LM741 as comparator that requires +Vcc -VEE from a 9V battery. Can this be accomplished using voltage divider? If so. How? If not, your suggestion.
     
  2. Audioguru

    New Member

    Dec 20, 2007
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    Any opamp can be biased at half the supply voltage then use a single polarity supply.
    But some 741 opamps do not work with a supply voltage as low as only 9V.
     
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  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    All the data sheets characterize the 741 for operation at +/-15 VDC, and never for single supply. If the 741 is an anemic op amp, it is a really bad comparator. Don't know what your inputs might be, but an LM311 would offer superior operation (it is a comparator).
     
  4. Nanophotonics

    Active Member

    Apr 2, 2009
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    I'm currently using the LM324 for my single supply applications.
     
  5. Audioguru

    New Member

    Dec 20, 2007
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    It is extremely slow. Its output has slew-rate limiting at only 2kHz and higher. Higher frequencies become triangle-waves with reduced level. The gain is only 12 at 40kHz. It has 3% crossover distortion because its output transistors have no bias current for low power. It is noisy.

    The MC33171 single, MC33172 dual and MC33174 quad opamps have exactly the same low power but have no crossover distortion, also operate from a supply as low as 3V and have a full output up to 35kHz. Their gain is nearly 40 at 40kHz. Their inputs work at the negative supply voltage that could be 0V. Their outputs go down very close to the negative supply voltage that could be 0V. But their output high current is only 3mA to 5mA.

    The MC34071 single, MC34072 dual and MC34074 quad opamps also work from a single supply as low as 3V and their inputs and outputs work down to 0V. They have normal supply and output currents and a full output up to 100kHz.
     
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  6. Nanophotonics

    Active Member

    Apr 2, 2009
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    Thanks for the explanation. You're the guru, so I leave it to the more knowledgeable.
     
  7. Slik_Willie

    Thread Starter New Member

    Mar 14, 2010
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    Thanks for the tip Guru.
     
  8. BMorse

    Senior Member

    Sep 26, 2009
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    to answer your question, yes there is a way you can get the +VCC and -VEE from 2 9 volt batteries to power a 741 opamp...


    [​IMG]

    B. Morse
     
  9. buckysparks

    New Member

    Mar 30, 2010
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  10. t_n_k

    AAC Fanatic!

    Mar 6, 2009
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    Another possible way of doing it using a 1/4 of LM324. Apologies to those who would love to see the back of LM324's.
     
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