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DIY Stompboxes => Building your own stompbox => Topic started by: Marco Pancaldi on March 17, 2005, 08:18:07 PM

Title: opamp gain question
Post by: Marco Pancaldi on March 17, 2005, 08:18:07 PM
Hi,

in opamps, the clipping behaviour is absolutely and only dependent from the rail-to-rail powering? In other words, if I overload the opamp sending too large signal to the input or using a too large feedback gain the clipping is the same (for the same "desired" voltage level)?

For example, in a Tube Screamer circuit, to use 4x booster BEFORE the opamp give exactly the same effect as using a 4x feedback resistor (I'm ignoring here all the details about feedback resistor values)?

And is this true for both non-inverting and inverting circuits?

Many thanks.
Title: opamp gain question
Post by: brett on March 17, 2005, 08:29:57 PM
My *guess* would be yes, the effect would be the same, because the signal level for all components in the op-amp except the input stage would be equal.  Experts?
Title: opamp gain question
Post by: loscha on March 17, 2005, 11:06:53 PM
that is pretty much how my lecturer explained it the other day to us.
input signal voltage or feedback train --- all dependant upon rail to rail voltage.
Of note is maximum current draw vs feedback resistors. You want to keep the resistors somewhere in the realm of not drawing too much current, but that shouldn't be a problem in a practical circuit: Only theoretical "for argument's sake" circuits.