I've just had a quick read of an RC circuit wikipedia page. The only thing I have like that is the 1uF capacitor at Vi and the resistors that connect to it.

It looks like I will need a series RC circuit. Do you know how I would start calculating the values for the resistor and capacitor? I found this RC calculator but I'm not really sure what kind of output I should be looking for.

I will do a few tests on the output from my PC and see what happens.