Hello all, could really use some help here. With the following schematic, I need to graph Vs vs. Vo. I need to know the function of R1 and R2. Lastly, if R2 value is increased to 440 ohms, what effect would that have? Here is a link to the data sheet for optocoupler ILD256. Any help is greatly appriciated. http://www.alldatasheet.com/datasheet-pdf/pdf/45334/SIEMENS/ILD256.html