Problem with Electronic Feedback?

[gunblaze]

Hi, i was reading through the topic on analogue electronics. And every single example on my text seems to just be just on the negative feedback on both the inverting and non-inverting input of an op-amp. What i would like to know is what's the difference between positive and negative feedback on an inverting and non-inverting op-amp. Will there be any changes in the formula to find the Voltage ouput of the op-amp?

 

[Mindscrape]

You can't use positive feedback on inverting and non-inverting amplifiers. Positive feedback is hardly ever used, but the most common use of it would be for a comparator. When the non-inverting input is at a higher voltage than the inverting input, the op amp will be positively saturated and put out the positive supply voltage. When the non-inverting input drops below the inverting input, the op-amp hits the other (negative) rail. Also, oscillators can be made with positive feedback.