I'm stuck on this problem, and I feel like if I could understand this one I'd be able to understand a lot more of my homework. I don't even know where to start..
Yes - good explanation.Thus the current through R equals Vin/R.
Very awesome. Okay, so I'm thinking the line connecting the resistance node and the - input doesn't even need to be there. Would that then make i -Vin/R? And where does a dependent source come in?Negative feedback is voltage fed from the output back to an input of the opposite polarity. In the case of an opamp it goes from the output to the (-) input. Due to the high open loop gain of an opamp the negative feedback thus will always try to keep the (-) input at essentially the same voltage as the (+) input. If there is a difference in voltage between the two inputs then the opamp gain will change the output so as to minimize this difference.
Looking at your circuit if the input source voltage raises the (+) input voltage, then the output voltage will rise until the current through the "Unknown device" is sufficient to raise the voltage across R1 so the (-) input voltage equals the (+) input voltage. Thus the current through R equals Vin / R.
That´s the question. Remember Ohm`s law.Shouldn't it be the same but negative, since there is no current coming out of the top of the resistor?
The line connecting the resistor to the -input is where your negative feedback comes from. Disconnect it and you don't know what will happen because the opamp is running without feedback and an undefined input signal on one input. It will probably either rail or flail.Very awesome. Okay, so I'm thinking the line connecting the resistance node and the - input doesn't even need to be there. Would that then make i -Vin/R? And where does a dependent source come in?
You should have in your text the dependent-voltage source model of an opamp. Try to find that (or look around on the web).OK, so would the equivalent circuit consist of a voltage controlled current source then, so that it depends on Vs? So it would still have Vs, R, the unknown device, and then a Vs/R current source pointing into the negative terminal of Vs?
OK, I am still having trouble understanding these. It makes absolutely no sense to me. Here is a picture of the configuration you mentioned:You should have in your text the dependent-voltage source model of an opamp. Try to find that (or look around on the web).
The figure shows an "equivalent circuit diagram" (not a "classical" circuit diagram with BJT´s or opamps) containing a controlled source.OK, I am still having trouble understanding these. It makes absolutely no sense to me. Here is a picture of the configuration you mentioned:
Why is there no connection between the input and the output? Is that what the arrow indicates?
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