I was reading up on op amp difference amplifiersone thing I haven't seen addressed explicitly is the impedance of your voltage signals. Suppose your input resistors are 100 and feedback resistors 1 Meg, for a gain of 10,000. Now let's say you are using a 100k pot to set one of the voltages going into the difference amplifier. Would this high impedance source affect the difference amplifier, like adding resistance to the input resistor, or does it matter?
17 years ago