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>> Now, let's talk about how a differencing or subtracting amplifier works.

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I've drawn the whole amplifier here,

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it's a combination of a inverting and

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a non-inverting amplifier with the two separate voltages Vs1 and Vs2.

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You can see that what happens right here is you have your feedback loop.

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Right here, I'm not going to scribble in the feedback loop.

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There's the feedback loop going to the negative connection and that's the feedback,

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we have one voltage right here connected onto the negative feedback.

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So, Vs1 right here is going to be the negative part of our equation.

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We can see that because the gain on the negative feedback is minus R2 over R1.

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This other term is going to be the positive part or Vs2.

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We can see that we only have positives right here.

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So, that's the gain that we're going to have on Vs2.

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We could basically look at that like bringing in Vs1 and multiplying it

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by the first gain, bringing in Vs2 and multiplying it by the second gain,

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and then adding them up.

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The only cool thing is that gain one is negative and gain two is positive,

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so we end up essentially subtracting off,

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part of Vs1 from Vs2.

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That gives us our output voltage.

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As with all of our op-amps.

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The V0 is limited between the two power supply voltages,

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Vcc and minus Vcc.