I recall being told a rule-of-thumb to use when figuring out what a circuit using an op-amp does: the voltage difference between the two inputs is always zero, at least to a first approximation.
ONLY in the case of negative feedback do you have a virtual short.
This might be a weird place to ask, but does anyone know a good place to discuss analog electronics online? A particularly good forum or something, that isn't full of cranks?
I'm not qualified to answer so I will. Electronics.stackexchange.com, not analog only obviously but good q&a spot like all the se sites, even with the occasional crank. Chat room too.
