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What is Op Amp?

Discussion in 'Amp Central Station' started by Churchjack, Apr 13, 2018.

  1. Churchjack

    Churchjack TDPRI Member

    Oct 22, 2017
    Please forgive my technical, particularly electrical, ignorance, but I see the phrase Op Amp everywhere around these here forums, and just cannot for the life of me figure out what it means. Please help, LOL

  2. Jules78

    Jules78 Tele-Holic

    Dec 12, 2016
    Northern VA
    It's a component of a circuit generally used to amplify the voltage difference between two inputs. It's the part of an amp that makes the voltage higher.

  3. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    It is short for operational amplifier. Way back when circuits were made of individual transistors with the other components, capacitors, resistors, diodes... . A transistor is the same as a tube or other device that can be used to amplify as signal. The problem with them is they are not perfect devices. They need to be configured using the other electronic parts that surround the gain stage and even then they are not perfect devices as they all distort the signal or affect or are affected by the signal source or by the load they are driving. Now if only there was a perfect gain device which asks little of the signal source, is not overly effected by the load it is driving, does not distort the signal and can supply as much gain as needed. This is the opamp. It is an amplifier with a number of stages and all the parts needed to make them work together in a tiny package.

    This is the first widely used opamp the 741.


    It has two inputs, one inverts the signal while the other does not. It can be treated as a perfect device, within reason, and circuits build around it. Simple right? But inside,


    And what it looks like under a microscope.


    In a way it is a shrunken version of a transistor power amplifier of the 70's. Now they are not perfect devices and there are a whole bunch of them to pick between as some are better at certain applications then others. In the guitar world the TL07x and TL08x (the x can be a 1, 2, 4, depending on which device it is) are the go to chips.

    The Tube Screamer. It hase the first opamp used to clip the signal to make distortion. The second opamp is used to act as a tone filter and to drive the output.


    Here is an opamp used to make a three band eq.


    And the list goes on as far as how it is used.
    uriah1, ajm763, Teleguy61 and 5 others like this.

  4. beyer160

    beyer160 Tele-Afflicted

    Aug 11, 2010
    On Location
    What he said.

    They look like this-
    ajm763 and jimash like this.

  5. Churchjack

    Churchjack TDPRI Member

    Oct 22, 2017

  6. printer2

    printer2 Poster Extraordinaire

    May 24, 2010
    Darn, a picture I never thought of posting, good addition. Those are a dip style packaging. Starting to be a obsolete part. Now days the electronic industry is going to surface mount technology. Those chips had the metal leads go through a hole to get soldered to the circuit board. Surface mount parts are placed on the board and soldered.


    No problem.

  7. 0utputXfmr

    0utputXfmr TDPRI Member

    Feb 10, 2018
    York, Pennsylvania
    Eh, some tinkerers using breadboards for prototyping will still produce some limited demand for the DIP format devices.
    ajm763 likes this.

  8. 0utputXfmr

    0utputXfmr TDPRI Member

    Feb 10, 2018
    York, Pennsylvania

    Each one of those symbols that consists of a circle with a vertical bar and two diagonal lines, one of which ends in an arrow, is a Transistor.

    Specifically, a Bipolar Junction Transistor, or BJT, for short.

  9. TeleTucson

    TeleTucson Tele-Holic Ad Free Member

    Aug 6, 2016
    Tucson, AZ
    You should start with the Wikipedia article which is pretty well-written and methodically constructed to build the concepts one at a time, taking you almost right away to the negative feedback configuration which gives op amps their versatility and robust performance:

  10. Billnchristy

    Billnchristy Tele-Holic

    Sep 21, 2017
    Very simple and useful devices. I have built audiophile preamps with them, had a phono pre that used them, etc...

  11. alnicopu

    alnicopu Friend of Leo's

    Oct 3, 2009
    Very useful and versatile little gizmo. Seems after we studied them in electronics school, they got used from then on. Easy to calculate gain in them also. Use positive feedback and it makes for a good, fast switch as well. Schmidt triggers, comparators, etc.

  12. Silverface

    Silverface Poster Extraordinaire Platinum Supporter

    Mar 2, 2003
    Lawndale CA
    As a helpful life hint - learn to use "Google". The answer pops right up. Same for about a thousand other questions that seem to get asked here, something I find quite baffling.

  13. archetype

    archetype Fiend of Leo's Ad Free Member

    Jun 4, 2005
    Williamsville NY
    I think we need a What Is... forum. It would be a link to and nothing else.
    Silverface likes this.

  14. ajm763

    ajm763 TDPRI Member

    Dec 14, 2008
    Southwest Ohio
    And for the extreme tinkerer, educator or engineer still living in the past (myself included) there's this one:


    They sell a 555 timer as well.

  15. bradpdx

    bradpdx Friend of Leo's

    Jul 16, 2006
    Portland, OR
    Let's see if this old EE can help...

    An OpAmp (operational amplifier) is an integrated circuit (IC) that forms a differential amplifier capable of very high gain. These properties - a differential input, rather than single-ended, plus the very high gain, make it ideal for designing circuits controlled by feedback, and that's the key.

    OpAmps were the first integrated circuits commercially produced in the early 1960s. They were immediate recognized by engineers as supremely useful. They were an idealized version of something that heretofore had only existed as a theoretical model.

    OpAmps greatly simplify analog circuit design, and I mean GREATLY. If you need to amplify a signal and get very consistent, easily calculated results, OpAmps are your friend. If you need to design a simple EQ circuit that will produce known, quality results with a small number of parts, OpAmps are your friend. If you want to design circuits that remain stable under a wide variety of temperature and power supply conditions, OpAmps are your friend.

    Any and all of the above would require extensive work and calculation to build with individual parts. With OpAmps, you can do a design in moments and test your ideas right away.

    I won't get into the details of feedback-based design, but that's the heart of why OpAmps matter and why they have fundamentally changed electronics since their introduction over 50 years ago.
    0utputXfmr likes this.

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