27-11-2016, 01:38 PM
To save talking at crossed purposes, do you mind if we approach this in steps?
First of all, do you understand how an inverting op-amp amplifier circuit works?
If it helps, there's an explanation here (about a third of the way down): http://www.markhennessy.co.uk/articles/op-amps.htm
It's easier to start with this because the op-amp has oodles of gain, so the actual behaviour is closer to the theory.
The 2 key questions to answer from that are:
1. Are you happy you know why the inverting input is called a "virtual earth"?
2. Are you happy that this amplifier works with currents, not voltages?
First of all, do you understand how an inverting op-amp amplifier circuit works?
If it helps, there's an explanation here (about a third of the way down): http://www.markhennessy.co.uk/articles/op-amps.htm
It's easier to start with this because the op-amp has oodles of gain, so the actual behaviour is closer to the theory.
The 2 key questions to answer from that are:
1. Are you happy you know why the inverting input is called a "virtual earth"?
2. Are you happy that this amplifier works with currents, not voltages?
