Can a 4049 be used as an opamp?

[hookus]

Specifically, a can I use one of the inverters as a unity gain buffer. If so, should I just treat the input as the inverting input on a standard opamp, and set up the feedback path that way?

[Steve Conner]

If it's a 4049UB, yes, maybe. Of course it will always be inverting with a gain of -1, not +1. Just watch out for instability too, they may not be unity-gain stable. There's probably a way to get round this. (In a regular inverting op-amp, you'd connect a resistor from the - input to ground, to reduce the noise gain, which is what determines the stability, without affecting the closed-loop gain much.)