calculating high pass roll off ?

[donald stringer]

I have the equation in this book on norton op-amps, 49 easy electronic experiments for  transconductance and norton op-amps. They give the schem.   component values, and the resulting frequency roll off. But in duplicating the equation to find out how they obtained there results I have not been able to duplicate the freq. roll off they obtained in the book. I am by no means an algebra wizard but there is only so many ways to do this equation. Given an input cap .001, input res. 4.7,feedback res. 470k, they give a roll off freq. of 3000hz. If they made a mistake on this calculation how can I trust the rest of the book?

[R.G.]

I don't know the exact circuit you're referring to.

The half power point for any single-R, single-C network is always
F= 1/(2*pi*R*C)

If the circuit has only the .001uF and the 4.7 (K?) resistor, I make it 33.9kHz. If the resistor that matters is the 470K, I make it 339Hz.

But this is a book about OTAs, not opamps, so the circuit might matter. OTAs are different.

If they made a mistake on this calculation how can I trust the rest of the book?

Well, it depends on your outlook. First, it would take an amazing bit of effort to get **every single calculation** in a book wrong, so at least some of them must be right. 8-)  Second, there is nothing perfect in the world. Happiness and success lies in being able to sort out what is wrong and not let it distract you from the good and right things that exist.

What is the sound of one error being made?  8-)