Lm741

Discussion in 'Homework Help' started by h.z, Nov 27, 2010.

  1. h.z

    h.z Thread Starter New Member

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    Can op amp LM741 work with 9V supply voltage?
  2. bertus

    bertus Administrator Staff Member

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    Hello,

    In the datasheet is stated ±5 Volts supply.
    This means taht 9 Volts is to low.
    Also there is stated that the LM741 is an obsolete component.

    Bertus

    Attached Files:

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  3. beenthere

    beenthere Retired Moderator

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    Dropped a place. That is +/-15 volts in the data sheet.

    What do you want to do? There are a huge number of better op amps, and many that are designed to operate with a single supply.
  4. Audioguru

    Audioguru New Member

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    The 741 opamp is 42 years old.

    The written spec's are only with a plus and minus 15V supply but the "typical" graphs all show a supply as low as plus and minus 5V. With a supply as low as only plus and minus 5V then the typical output swing is shown to be almost nothing.
  5. h.z

    h.z Thread Starter New Member

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    i asked just because I'm curious. 9V battery is easy to get, that's why I was wondering if the op amp could work with 9V supply voltage. as far as i know, op amp can amplify the input voltage to maximum the supply voltage. right?

    so, audioguru op amp LM741 could work with 9V supply voltage?
  6. thatoneguy

    thatoneguy AAC Fanatic!

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    You can use two 9V batteries to supply it, connect negative to positive, call that point "ground", for a dual supply.

    That is sub-optimal, I'd suggest going with a more modern op amp.
    Last edited: Nov 27, 2010
  7. Audioguru

    Audioguru New Member

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    "Negative to negative" does not make a dual-polarity supply.
    It makes two positive supplies which are not useful.
  8. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    You could also use something like a LM324, which is 4 in one package. That chip is rated from 3V to 30V, which similar specs to a LM741. Both are available at Radio Shack.

    The LM741 is extremely old, which translates into very poor specs compared to more modern types.

    Creating a Virtual Power Supply Ground
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  9. h.z

    h.z Thread Starter New Member

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    Minimum supply voltage is 3V? that is very low. so, you're saying i could use 9V supply voltage for LM741?
  10. retched

    retched AAC Fanatic!

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    No, you cant use one 9v battery with a 741.

    Take 2 9v batteries connect them in series.

    Take the '+' on battery 'A' and connect it to the '-' on battery 'B'

    The wire that connects the two batteries can now be your GROUND.

    The '+' on battery 'B' is now +9v Hook that to the positive supply pin on the 741
    The '-' on battery 'A' is now -9v Hook that to the negative supply pin on the 741

    That will allow you to work with a LM741.

    If you are just trying to learn theory, then thats fine, but If you are trying to make a project to keep and use, you can, and should, find better OPAmps.
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  11. Audioguru

    Audioguru New Member

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    Simply read the datasheet.
    The written spec's guarantee operation only when the supply is a total of 30V.
    The graphs show very poor performance for "typical" devices at low voltages down to 10V.
    Some do not work when the supply is 10V or less.

    A 9V battery drops to only 6V as it is used.
    An MC34071 or TLE2141 opamp works well with a supply down to only 3V and 4V. Both have guaranteed specs with a 5V supply. They have very low distortion and produce full output at 100kHz. Duals and quads are available.
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  12. h.z

    h.z Thread Starter New Member

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    thanx a lot audioguru and retched. i learn a lot. :)
  13. Georacer

    Georacer Moderator Staff Member

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    So I guess the reasons they made us use it last year in a project in university where purely historical? :p
  14. bertus

    bertus Administrator Staff Member

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    Hello,

    Here I have a couple of PDF from Texas Instruments that might interesr you.

    Bertus
  15. prateek_ullengal

    prateek_ullengal New Member

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    yes u can operate with 9v as well as 12v....
    depends on your application
  16. Audioguru

    Audioguru New Member

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    Many modern opamps work perfectly from a 9V battery that slowly drops to only 6V, but not a 741 opamp.
  17. R!f@@

    R!f@@ AAC Fanatic!

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    throw the 741 out of the window.

    Get the most reason single ended supply opamp.
    Will work with 9V and will last longer in a battery app.

    I wonder why Indian uni's still get the students to use those obsolete components.

    Oh wait, I forgot.. it's all they have around in thousands.
  18. JoeJester

    JoeJester AAC Fanatic!

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    Nope. The reason the universities use the 741 is the same reasons you don't use them. They make great training aids.
  19. beenthere

    beenthere Retired Moderator

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    Not at all. Every instructor has a moment of pure pleasure every time another 741 goes in the trash.
  20. Bill_Marsden

    Bill_Marsden Moderator Staff Member

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    Agreed. All a standard op amps flaws happen much sooner with a 741.

    I mentioned the LM324 as an alternate to the 741. I talked about what a LM324 could do with power supply voltages. It is almost as old as the 741 though, there are much better out there.

    For all their flaws, which are legion, they are tough little chips, and a lot of them were made.
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