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While trying to understand about op-amps, most tutorials show how op-amps can be used as adder, subtracter and an averaging amplifier. However none of the tutorials gives any real world examples for those type of circuits.

Could you please give some real world examples for using op-amp as adder, subtracter and an averaging amplifier?

Specifically, why do we need to add up voltages? or subtract? or need to find average?

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closed as too broad by Harry Svensson, ThreePhaseEel, PeterJ, Sparky256, Voltage Spike Dec 28 '17 at 0:32

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ It would take a book to answer your questions, which is where you should start. Buy, beg or borrow books that relate to your numerous questions. As it is a good answer would be very broad. \$\endgroup\$ – Sparky256 Dec 23 '17 at 21:36
  • \$\begingroup\$ Go find "op amps for everyone" and read the whole document \$\endgroup\$ – Voltage Spike Dec 28 '17 at 0:32
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Op-Amp Adder: mix bus summing amplifier as used in audio mixing consoles.

Op-Amp Subtracter: Differential amplifier: remove common-mode signal from a differential signal source.

Averaging amplifier: The link that you provided as a comment shows the op-amp configured as an integrator. These have several uses but one of the most common is a type of signal generator known as a function generator. The integrator stage creates an output ramp signal. This can be a triangle wave or saw tooth, depending on charge and discharge currents.

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  • \$\begingroup\$ Like shown in at "As Averaging Amplifier" section at electronicspost.com/… \$\endgroup\$ – Junaid Dec 22 '17 at 4:38
  • \$\begingroup\$ You could also add AGC; a classic error amplifier configuration. \$\endgroup\$ – Peter Smith Dec 22 '17 at 12:38
  • \$\begingroup\$ @Junaid - No. "Average" can have two different meanings: instantaneous or over time. The link you give shows a circuit which takes the instantaneous average of several inputs. If you configure an op amp as an integrator, at the end of some time interval the output will be the average of the input over time (times the interval, which must be divided out). \$\endgroup\$ – WhatRoughBeast Dec 22 '17 at 12:56
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There are many active filter circuits and and sine-oscillator configurations which contain opamps wired as adder and/or subtractor blocks as well as integrating units.

Examples (names of the inventors):KHN, Tow-Thomas, Fleischer-Tow, Akerberg-Mosberg,...

More than that, all active filters derived from passive reference circuits are using also these active blocks (leapfrog- structures, Follow-the-leader and Primary-resonator blocks).

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