OP amp LM741

Discussion in 'General Electronics Chat' started by jepoy, Oct 1, 2010.

  1. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    I am making a audio amplifier using OP amp lm741 for my project.
    I tried searching for a circuit diagram but all I got is like this.
    http://www.electronicecircuits.com/electronic-circuits/12w-amplifier-using-741-op-amp/
    it needs a negative voltage input but since I dont have transformer and I want it to be like a pocket amplifier, so I decided to search for more circuit diagrams and then I found this one.
    http://www.gwellwood.com/electronics/741amp.jpg
    it doesnt need negative voltage, so I was like " Ok this is the right one." but I want it to be a pocket amplifier just using a 9 volt battery.
    heres my question.
    Can I/How to change the 12v to 9v?
    do I just use 9v battery to run it or I need to do some changes w/ the circuit.
    please help me guys.
    please~

    thanks.
     
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Do you HAVE to use a 741? There are tens-of-thousands of better opamps for audio. Many that only need a single power supply (no negative) and many with better audio performance with lower distortion..

    You may want to consider an upgrade.
     
  3. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    I tried searching for a new one but I cant find any. ) :
     
  4. retched

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  5. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    do you have any circuit diagram?
    I cant buy online. ) :
     
  6. retched

    AAC Fanatic!

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    Here you are:
     
    Last edited: Oct 1, 2010
  7. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    weird I cant open the file.
     
  8. Jaguarjoe

    Active Member

    Apr 7, 2010
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    If you're stuck with a 741 then so be it but Retched is right, 741's are ancient technology. Maybe if you look through the e-books on this site you'll get a little more insight into picking op-amps. They're like women though, everyone has their favorite(s).

    If you want to run your circuit at 9 volts, it will be OK as is, however, you will no longer have the output voltage swing that you would have had with 12 volts.
     
  9. retched

    AAC Fanatic!

    Dec 5, 2009
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    You have WORD installed? Or OpenOffice?
    Try opening the file again.
     
  10. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    nvm, I already opened it. ( :
    yea, its too old and its not the best op amp.
    but if you can give a circuit diagram using a new op amp ( Ive been searching for like 2 days still I cant find any.) it would be nice. ( :

    edit:
    thanks retched.
     
  11. retched

    AAC Fanatic!

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    You can use the same circuit diagram.
     
  12. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    ^ the one that you gave? ( :
     
  13. retched

    AAC Fanatic!

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    Yes. If you get a better opamp, you can use the same schematic. If you get an opamp that only needs a single(+) supply, then you can just connect the (-9v) to GND and everything else is the same.
     
  14. Audioguru

    New Member

    Dec 20, 2007
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    Retched posted a WORD document instead of a few PNG files of a 42 years old opamp trying to drive a speaker. It is not a power amplifier so it cannot drive a speaker (it does but it is extremely low level before severe distortion).
    The old 741 opamp is designed and is spec'd with ONLY a 30V supply and many of them do not work if the supply is as low as 9V. It has trouble above only 9kHz but many people can hear frequencies that are twice as high and better opamps work perfectly up to 100kHz.

    Why not use a power amplifier IC that is designed to drive a speaker?? There are about 120 of them available. Big ones, little ones, high power ones and low power ones.
     
  15. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    We really need to use a op amp for this project.
    coz we already made a power amp. Op amp would be our second project.

    my pocket size power amplifier. same size of a zippo lighter.

    [​IMG]
     
    Last edited: Oct 2, 2010
  16. Audioguru

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    Dec 20, 2007
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    In your first post you showed the schematics of two power amplifiers that use a very old 741 opamp. The second circuit has awful crossover distortion. You forgot to say which one you made.
    Why do you need a second opamp? What will it do?
    If you don't explain the functions that you need then we cannot help you.
     
  17. jepoy

    Thread Starter New Member

    Oct 1, 2010
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    All I need is to make a Audio amplifier using OP amp ICs(the good one) and running on 9v battery.
     
  18. Audioguru

    New Member

    Dec 20, 2007
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    Again I am asking what will be the function of this new "audio amplifier"?
    What is its input (and what level is it) and what is its load?
    What amount of gain is needed?

    I have used TL071 single, TL072 dual and TL074 quad audio opamps for most of my 40 years electronics career. They are low noise, have very low distortion, have full output to 100kHz and are inexpensive. They have Jfet inputs so their input resistance is 10 giga-ohms. Their minimum spec'd supply is 7.0V but I have used them with 6V without any problems.
     
  19. Wendy

    Moderator

    Mar 24, 2008
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    Radio Shack carries the TL082 Op Amp, which is very similar.

    What part of the world are you? Most of the old hands put their location (city, state or country) in their profile. This helps recommend parts occasionally.

    Oddly enough, I'm helping my boy with his first project, a 2 channel preamp between his speakers and his computer. I'm going to use some very cheap decent op amps, NJM4565. I'm going to have him use a socket in case it isn't good enough.

    It is an updated version of the 1558, which in turn is a more modern 741 in a package with two op amps (referred to as a dual op amp). The 741, 1458, and 1558 have really bad frequency responses, most older op amps do. The more modern ones are better, but there is still room for improvement.

    Bill's Index

    High Speed Op Amp Query
     
    Last edited: Oct 2, 2010
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Must be a million op amps out there that would work in place of a 741, I see no problem plugging a standard TL082 in place of the 741 if you follow the pinout differences but if this circuit is old enough to call for a 741 chances are the transistors won't be available anymore. What gets me is their numbers are high enough on the scale you wouldn't think they'd be that old.

    Your output circuitry already requires a + & - source so that's no big deal, and it will likely run just as well on +/- 9V as it will on +/- 12V however .....

    Most any car audio amp IC will still work with +9V and ground but you'll never be able to get 12W out of one.

    If you can't buy online can you buy locally? Where are you located?
     
    Last edited: Oct 2, 2010
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