Customer Reviews

Understanding Circuits: Learning Problem Solving Using Circuit Analysis (Synthesis Lectures on Electrical Engineering)

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I won't comment on the misleading title nor the fairly convention chapters 1-6 but the op amp bit of this book is all wrong - starting (and ending) with the model. The analysis above Fig 7.2 only works if no current flows between v+ and v- (and if some unstated labelling a,b anc c is assumed). The model development then goes on to say that somehow because the output is limited by the rails voltage that the input is forced to zero - which is not the case. This ONLY happens with negative feedback. The only operating assumption (of the two stated) that can be made without negative feedback is that I-=I+=0 (on the basis of high input impedance, "ideally" infinite). The second of the stated operating assumptions does not apply unless negative feedback exists and then it is easily demonstrated and modelled assuming ideality (we don't have to even mention rails voltages at this stage).
Might sound like a small issue but, for me, it is fundamental and would lead to serious misconceptions for the audience this book is aimed at. The poor modelling does not simplify or reflect the real world. A big important confusing mistake.