741ce OP amp help..

Discussion in 'General Electronics Chat' started by chunkmartinez, Dec 23, 2012.

  1. chunkmartinez

    Thread Starter Senior Member

    Jan 6, 2007
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    Some of you may know, I'm working on a clipping detector circuit...Well I haven't used OP amps before in the real world and I cannot ge a simple expiriment to work.

    Heres what I tried:

    9 volt or 7 AAs in series for the power supply, a non split power supply just 0v GND and the pos of the batt...

    I tried Grounding the inputs in common mode from the power supply GND so that I can see the offset..I get the full saturated output though. If I attatch a negative feedback lead I believe I get .40ma but a potentiometer dosn't change the value when I turn it and I have it connected to the null pins. So is it possible that without a negative feedback lead I will get saturation at the output while the inputs are grounded? And why dosn't the pot change the offset value?
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,790
    RTFDS!! The 45-year old, totally obsolete 741, needs dual supplies or a single supply with a virtual GND at Vcc/2

    Get a modern part that can run with a single supply and stop wasting your time.
     
  3. Audioguru

    New Member

    Dec 20, 2007
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    I would also like to say that to nOObs but what does it mean?

    I agree that only teachers and school kids use the obsolete 741 opamp today.

    Look at the MC34071 single, MC34072 dual and MC34074 quad opamps. They have inputs that work at ground and have an output that goes almost down to ground with a single positive supply. They go very well as high as 100kHz.
     
  4. Papabravo

    Expert

    Feb 24, 2006
    10,144
    1,790
    It means "Read the datasheet, before using the part". No matter what you think it says and no matter what the textbooks tell you the only authoritative source is the datasheet. For this part I'm not even sure there is a manufacturer that publishes a current one. That, in and of itself, is a huge clue that you need to find a more current part lest everything you learn be rendered useless.
     
  5. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    MC30472 Dual Op Amp Datasheet

    That is a decent single rail Dual Op Amp that outclasses the 741 in every aspect. The biggest differences are that it is has 2 op amps in one package, and runs from a single supply. The slew rate is also higher so that it can work with higher audio frequencies than the 741 can.
     
  6. Audioguru

    New Member

    Dec 20, 2007
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    Lazy teachers who do not teach and lazy students who do not learn should be shot, set on fire then drawn and quartered.

    Many students today are not interested in ANYTHING so they select a career at random. They do poorly in the career. Like many teachers.
     
  7. chunkmartinez

    Thread Starter Senior Member

    Jan 6, 2007
    180
    1
    Guys I also have a ual TL082, is this fine to work with?
     
  8. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    The TL082 also requires a dual power supply; it can't get within about 1.5v of +V nor within about 3v of -V. As has already been said, you should learn how to read the datasheet.

    It's not easy at first, but the more you read and try to understand them, the more sense they will make.
     
  9. chunkmartinez

    Thread Starter Senior Member

    Jan 6, 2007
    180
    1
    Well I'm going to use a simple resistor dual power supply first When I recieve my rail splitter I will use it. I'm going to use a high resistance load to try and insure balance..
     
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