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Op Amp 741

Discussion in 'General Electronics Discussion' started by colum, Oct 25, 2016.

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  1. colum

    colum

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    Jul 25, 2013
    OpAmp.jpg I am trying to find the wiring for a 741 Op Amp as a simple Buffer of a Sine Wave with a 15 + Volt and a 15 - Volt Regulated supply.. I hope my diagram shows up and if it doesn't I would appreciate advice on the pin numbering...Thanks...colum
     
  2. Alec_t

    Alec_t

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    Jul 7, 2015
    Googling "741 amplifier schematic" gives lots of hits. Be aware, though, that the 741 is an out-dated opamp with a poor frequency response and limited input/output voltage ranges.
     
  3. AnalogKid

    AnalogKid

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    Jun 10, 2015
    Your schematic is fine as far as it goes.

    1. It needs decoupling capacitors on both power pins. A minimum is a 0.1 uF ceramic capacitor from pin 4 and pin 7 to ground. Keep the leads as short as possible. Better is to add a 10 uF electrolytic cap in parallel with each 0.1 uF ceramic.

    2. There is no ground reference shown for the input signal. Without it, the output will not be centered about ground. If the input signal is AC coupled through a series capacitor, add a 100 K resistor from pin 3 to ground as a start.

    ak
     
  4. colum

    colum

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    Jul 25, 2013
    Thanks for your swift reply Alec_t, what I want to do is generate 400 Hertz at 115 v to drive an old Analog frequency meter at about 7 Watts and then the circuit may be used for parts ...Thanks again for your Similar threads..colum
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    well you are not going to use an op-amp for that, you will kill it

    explain you idea much more clearly
     
  6. colum

    colum

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    Jul 25, 2013
    Thanks for your very good advice AnalogKid, I wonder about name "AnalogKid" if you need some analog meters I have some for free (just postage) colum
     
  7. Alec_t

    Alec_t

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    Jul 7, 2015
    Can you post a link to this frequency meter? I'm surprised it needs a 115V input and 7W.
     
  8. colum

    colum

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    Jul 25, 2013
    I was going to use the 741 just to buffer the signal from a Signal generator into Transistors into a reversed Transformer, the only load on the 741 is the Hertz signal ... The load will be on the - + power supply and the Transistors...Thanks...colum
     
  9. davenn

    davenn Moderator

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    Sep 5, 2009
    still really unclear

    what voltage and power level is the 400 Hz ?
     
  10. colum

    colum

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    Jul 25, 2013
    These are called Vibration Meters also called Tuned Reed meters, I will send a picture
     
  11. colum

    colum

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    Jul 25, 2013
    Not sure what you mean by power level but it draws about 7 Watts at 115 V and is just meter not a relay
     
  12. davenn

    davenn Moderator

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    Sep 5, 2009
    it's quite simple
    you said you have a 400Hz signal that you want to feed into the op-amp
    what voltage and power level is it ?
     
  13. Alec_t

    Alec_t

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    Jul 7, 2015
    If the meter is anything like this one, it covers a frequency range of less than one octave. Does yours? If so, it would probably respond unambiguously to a square-wave input. A square-wave at high voltage would be much simpler/cheaper to generate than a sine-wave.
     
  14. BobK

    BobK

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    What is the signal generator? It probably already has drive capability at least as good as your 741.

    Bob
     
  15. colum

    colum

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    Jul 25, 2013
    , My meters are all 115 volts and range from 20Hz to Hundreds , All of them that I can check between 20 and 60 Hz work even with non Sine wave.I want to build a circuit to check the 400 Hz.
    I also have Reed meters that work by contacting the frame of a motor and probably sense the rotating armature and these are accurate as well
    Right now I must build a 400Hz 115v power supply just to see if they work
    That is a very nice meter that you have and looks similar to one that I have except mine is a contact type 60 Hz
    Jeff
     
  16. davenn

    davenn Moderator

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    Sep 5, 2009
    This thread is dreadfully confusing because of the lack of clear info from the OP


    @colum PLEASE show photos of the front panel of your signal generator and of the frequency meter


    no one else answer till that happens !
     
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  17. colum

    colum

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    Jul 25, 2013
    Sorry about the confusion but all I wanted was a comment about an OpAmp and I got involved in a discussion about the purpose...anyway I will try to send a pic of some of the Reed meters
     

    Attached Files:

  18. colum

    colum

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    Jul 25, 2013
    This is a contact type Reed meter that does not require electricity bujt probably senses the armature rotating I have not tested this meter all my motors are 2700 rpm other meters do work on 2700
     

    Attached Files:

  19. colum

    colum

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    Jul 25, 2013
    Well Davenn I do appreciate your attention in all of this but I would like to know what you meant with "Voltage and Power level" I worked on very high Voltage 120 t0 480 Volts unlimited Amps but I'm not too familiar with Electronic jargon. I can send pics of all of these antique meters if you are interested...Jeff
     
  20. davenn

    davenn Moderator

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    Sep 5, 2009
    Hi Jeff

    cool meters, I haven't seen any of them for quite some time :)

    I am just desperately trying to find out what the poor op-amp is doing and making sure you understand that it cannot handle the voltage levels you are referring to
    So I still don't know ( and it seems, nor do others) where the op-amp fits in to all this

    so again I ask, what is the voltage and current levels you are feeding into the op-amp from this unknown signal source that you also still haven't given the request info about


    Dave
     
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