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## Differentiating Op-Amp basic exercise

 In the last calculation with Vout = 8V this means that the voltage at the output of the amplifier would be +12V (8V + that 4V battery)
Oh! I was not aware of this, technician. I will ask my teacher tomorrow morning as I have a class with him.

Thanks. I will let you know, I promise.

 By the way, the most basic set up to look at is when there are no extra batteries added The equation then becomes Vout = -Vin x R2/R1
Duly noted

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 Quote by Femme_physics Thanks, master!
That's all right.

 Quote by Femme_physics Well, yea, I ask Klaas ..........
He must be really smart then!
Who is he?

 Quote by Femme_physics You mean the development of the formula? No, not really. It's a bit blurry to me.
Oh well, perhaps some day soon the fog will rise.

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Nice pic!

 He must be really smart then! Who is he?
He is Klaas, The Klaasmaster of all Classes

 Oh well, perhaps some day soon the fog will rise.
I bet!

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 Quote by Femme_physics Oh! I was not aware of this, technician. I will ask my teacher tomorrow morning as I have a class with him. Thanks. I will let you know, I promise.

As promised! Yes, you were right, my teacher confirmed it and also added it was not his exercise, and that there must be a mistake.
 Thank you so much for letting me know. I hope you feel good about op-amps !!!!
 Recognitions: Gold Member Almost! trying to figure out their basis of operation here. And of course, you're the one who should be thanked!
 I have looked at your 'here' It is a basic circuit. I will put something together for you about op amps. There are lots of technical details and it is easy to get confused by them. Most of them are not important. The basic principles are not hard to get to grips with. I will keep in touch with you about op amps Cheers

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Yes, most websites I've seen do include a lot of seemingly unnecessary confusing nitty-gritty info.
 I will put something together for you about op amps. There are lots of technical details and it is easy to get confused by them. Most of them are not important. The basic principles are not hard to get to grips with. I will keep in touch with you about op amps
Cheers

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 Quote by I like Serena Well, your formula does not make sense to me. And I also do not understand why your teacher called it a differentiating amplifier. It isn't. It's also not a differential amplifier, although your new formula is for that. Here's a picture of a differential amplifier. The corresponding formula (symbols from the picture) is $V_{out} = (V_2 - V_1) {R_f \over R_1}$
Hey Serenophile,

Maybe you can explain something. I thought that every op-amp was a differential amplifier in the sense that it amplifies the difference between the + input and the - input. Why, then, is there a specific configuration referred to as a differential amplifier above? Is it just because op-amps are never operated open-loop, and what you have above is the stable, closed-loop op-amp design that happens to produce a differential output?
 Mentor I should also probably contribute something useful to this thread rather than just hijacking it, right? Umm...okay. To the OP: here is a link to a site with some info on op-amps: http://hyperphysics.phy-astr.gsu.edu...ampcon.html#c1

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 Quote by cepheid Hey Serenophile, Maybe you can explain something. I thought that every op-amp was a differential amplifier in the sense that it amplifies the difference between the + input and the - input. Why, then, is there a specific configuration referred to as a differential amplifier above? Is it just because op-amps are never operated open-loop, and what you have above is the stable, closed-loop op-amp design that happens to produce a differential output?
Hey Asterophile!

Yes it amplifies the difference by a million.
But for a difference we do not want amplification by a zillion, we want *just* the difference.
An additional complication with amplification by a zillion, or open-loop in general, is that the op-amp gets saturated and just gives off either max + or max -.

As an added bonus the differential amplifier configuration allows us to set an amplification that deviates from 1.

 Quote by cepheid I should also probably contribute something useful to this thread rather than just hijacking it, right? Umm...okay. To the OP: here is a link to a site with some info on op-amps: http://hyperphysics.phy-astr.gsu.edu...ampcon.html#c1