# Op amplifier circuit

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#1
I have a question related to functioning of op amp.
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#2
I have posted the question and the graph i need to sketch on. I sketched a line from origin to 6v because Vout= gain + r1/r2 . So if let say input voltage is 1v output should be 6v. right? If you can help me out with this it would be great.
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4 weeks ago
#3
(Original post by papie)
I have posted the question and the graph i need to sketch on. I sketched a line from origin to 6v because Vout= gain + r1/r2 . So if let say input voltage is 1v output should be 6v. right? If you can help me out with this it would be great.
An ideal op-amp is assumed to have infinite gain. The input voltages (- and +) must therefore be equal. You have a voltage divider supplying the '-' input voltage, as a fraction of the output one. The inputs are also assumed to take zero current. Can you derive a formula for the output voltage? (It's not what you stated)

What is the maximum voltage that the op-amp can supply?
Last edited by RogerOxon; 4 weeks ago
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4 weeks ago
#4
I don't normally like telling people to just memorise things but I think op amps are a bit of an exception

I'd suggest you learn to recognise the inverting and non-inverting configurations and memorise the formulae for their voltage gain as part of your revision

it's worthwhile and (hopefully) fun to go through the derivation of the gain formulae but you probably don't want to start doing it in an exam.

here are the reasoning and voltage gain formula for inverting and non-inverting configuration

https://www.electronics-tutorials.ws/opamp/opamp_2.html
https://www.electronics-tutorials.ws/opamp/opamp_3.html

and here is a video if you follow it better like that https://www.youtube.com/watch?v=7FYHt5XviKc&t=579s
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#5
(Original post by RogerOxon)
An ideal op-amp is assumed to have infinite gain. The input voltages (- and +) must therefore be equal. You have a voltage divider supplying the '-' input voltage, as a fraction of the output one. The inputs are also assumed to take zero current. Can you derive a formula for the output voltage? (It's not what you stated)

What is the maximum voltage that the op-amp can supply?
Oookay I get it. I think I was too tired last night when I was doing it. The output is going to be saturated at 3V so it can't be 6V.
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