operational amplifier

Discussion in 'General Electronics Chat' started by fireintheit, Aug 13, 2014.

  1. fireintheit

    Thread Starter New Member

    Jun 14, 2014
    16
    0
    I just setup a non-inverting circuit using an tlc272 op amp cp. But I am not sure of what the op amp does. I am using a potentiometer to control the voltage supply. I believe there is suppose to be some type of gain but when check the amount of current flowing through the circuit (using multimeter), the amount of current in the output is equal to the amount of current in the in the input. I have connected the positive input to 9 volt battery and the negative input to ground.

    I was wondering if some could explain what op amps are used for?
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    Schematic? Where?
     
  3. to3metalcan

    Member

    Jul 20, 2014
    228
    23
    Yeah. Schematic. The circuit you're describing really makes no sense according to the way you're phrasing it.
     
  4. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,645
    759
    My assistant is trying hard to get the schematic
     
    to3metalcan likes this.
  5. crutschow

    Expert

    Mar 14, 2008
    12,982
    3,221
    Standard op amps are a voltage gain block with a very high open loop voltage gain and a non-inverting circuit should provide non-inverting voltage gain. Your mention of input and output current "flowing through the circuit" makes no sense. Post your circuit schematic.
     
  6. fireintheit

    Thread Starter New Member

    Jun 14, 2014
    16
    0
  7. fireintheit

    Thread Starter New Member

    Jun 14, 2014
    16
    0
    can some explain what voltage gain actually is. I am not sure why some would use op amps in circuits?
     
  8. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
  9. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    Example.
    I setup amplifier to provide gain of 6.
    I put 1 volt in. I get out 6 volts.
    Input 1 volt.
    Output 6 volts.
    I have successfully amplified 1 volt into 6 volts.
     
  10. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    How is the opamp powered?

    Bertus
     
  11. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    As far as I can see, either power wire or ground wire are missing. It does not seem to be powered.
     
  12. crutschow

    Expert

    Mar 14, 2008
    12,982
    3,221
    Say you have a small signal from some type of sensor and you want to make it larger so you can process it with an A/D converter. For that you can use an op amp to amplify the voltage from the small sensor voltage (say 100mv) to a voltage that the A/D input needs (say 5V) so you use an op amp circuit with a gain of 50.

    Op amps are sort of the swiss-army-knife gain block of analog circuits. That can be configured to do all sorts of functions such an amplifier (single-ended, differential, trans-impedance), active-filter, integrator, differentiator, oscillator (sinewave or square-wave), precision rectifier, etc.

    Edit: You seem to have only a vague knowledge of electricity and electronics. I suggest you read some tutorials on that subject.
     
  13. to3metalcan

    Member

    Jul 20, 2014
    228
    23
    That picture is not very helpful. I can't make out the resistor values, nor can I even tell if you have the op amp the right way around. Here's a better question: what were you TRYING to do with this circuit?

    (You also, as Shteii noted, don't seem to have connected it to power. Not to mention your schematic has two resistors and I see three here!)
     
  14. fireintheit

    Thread Starter New Member

    Jun 14, 2014
    16
    0
    The red wire is the connection to ground, I have set -1 input to ground.
     
  15. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    Ok. That is Pin 4.

    Then you have no power (Vdd) to the chip. The positive voltage from voltage supply (+15 volt normal max., +18 volt absolute max.) goes to the top right pin (Pin 8).
     
  16. bertus

    Administrator

    Apr 5, 2008
    15,645
    2,344
    Hello,

    Pin 8 is not per definition the +Vcc.
    Here are the pinouts from a couple of opamps, taken from the datasheets:

    [​IMG]

    Bertus
     
  17. ramancini8

    Member

    Jul 18, 2012
    442
    118
    You proved that op amps are useless; something I suspected for years. Still, why do they make billions of these things every year?
     
  18. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,669
    804
    How the hell did you come to that conclusion? Opamps are useless only if you have no clue on how to actually use them. Reading the datasheet goes a long way.
     
  19. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,378
    494
    They provided the model of the op amp. I got datasheet for it. Datasheet says positive power supply is applied to Pin 8.

    Why are you wasting your and everyone else's time?
     
  20. to3metalcan

    Member

    Jul 20, 2014
    228
    23
    Congratulations all around; this goes a long way toward proving my thesis that ELECTRICITY IS A HOAX! :D
     
Loading...