K
krw
Guest
In article <6v1206FgjlikU1@mid.individual.net>, notty@emailo.com
says...>
doesn't have anything to do with the voltage across the OpAmp's
input.
exceeds the power supply rails (minus some bit for most real
OpAmps), yes there will be distortion and, yes, the inputs will no
longer have 0V across them. It will *seek* (i.e. try) to drive the
input voltage to zero, but it can't.
says...>
Ok, if your drive exceeds the OpAmp's rails, sure. But that"krw" <krw@att.zzzzzzzzz> wrote in message
news:MPG.23f4fa16439e97e2989944@news.individual.net...
Not sure how the op amp itself settles when V- = V+.
Negative feedback. If the output wanted to be too high, the
current in R1 would be too high forcing V- high, causing the output
to go lower. ...until the voltage between + and - is zero.
I just know that the amp acts like a variable PSU and what
voltage E1 needs to be to get V- to equal V+.
If it's not (the negative feedback can't stabilize it) the output
has to go to one rail or the other ("infinite gain").
The method to stabilize is feedack. Feedback through a resistor ensures
that V- = V+, but is it not an internal fuction of the OP Amp that Vout
stabilizes are the required voltage (Set by extermnal networks) when
V- = V+?
Right. If V- <> V+ the output is infinite, so they must be equal
or the feedback isn't doing its job.
I suppose you could make an Op Amp where
Vout stabilzes when there is 1V across V- and V+?
You wouldn't. To do so one would need a 1V reference, something
that is completely unnecessary and unwanted.
What I'm thinking about is this: If I had an audio amplifier speaking into
the microphone I might drive the ouput transistor into distortion.
doesn't have anything to do with the voltage across the OpAmp's
input.
If the output voltage needed to drive the input voltage to zeroBut if I had some negative feedback I could ensure that the distortion was
less. But, the amplifier does not seek to drive the input to zero and
achieve stabilization there.
exceeds the power supply rails (minus some bit for most real
OpAmps), yes there will be distortion and, yes, the inputs will no
longer have 0V across them. It will *seek* (i.e. try) to drive the
input voltage to zero, but it can't.