[Neuroscience] Re: Op Amps - The Voltage Follower Circuit

J.A.Legris via neur-sci%40net.bio.net (by jalegris from sympatico.ca)
Fri Feb 13 23:29:30 EST 2009


On Feb 13, 8:16 pm, Bill <connelly.b... from gmail.com> wrote:
> I'm having a hard time understanding the classical Voltage Follower
> Circuit made by a single op amp. I wont bother trying to draw it in
> ASCII, just have a look here if you don't know what I'm talking about:
>
> http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/opampvar2.html
>
> This is who I'm thinking about it (which I'm sure is wrong):
> 1) Lets imagine you have a 1mV input to the + input.
> 2) At the instant this is switched on the - input is 0, so the op amp
> outputs 1mV
> 3) Now the + input still gets 1mV and - input gets 1mV, so the amp
> outputs 0mV, sending us back 1)
>
> I appriciate that the op amp works 'instantaneously' so you don't get
> oscillations like I described, but I still don't know how one can
> conceptualize op amps without getting into these kind of oscillations.
>
> Thanks for anyone who can tell me the correct way to think about this

Recommended reading:

http://www.analog.com/library/analogDialogue/archives/39-05/Web_ChH_final.pdf

--
Joe



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