Deriving the relationship between V_in, V_out and V_ref in a Schmitt trigger

[WlfordBrimley]

Homework Statement

Please see refer to the attached picture of a Schmitt Trigger. How can you derive a relationship between V_in, V_out and V_ref, given values of R1, R2, R3,R4 and V_cc?

Homework Equations

Golden Rules for an Op Amp, voltage divider equations, etc.

The Attempt at a Solution

I'm not sure where to start, any suggestions/hints would be appreciated.

 

[Reshma]

It would be helpful if you could post some of the equations you have started with. I will give you few hints:
*Input voltage is applied at the inverting end.
*Positive feedback is used.
*Obtain the feedback factor from the potential divider arrangement.
*Establish relationship between the feedback factor, ref. voltage and saturation voltage.