In the previous experiment we mentioned that a 0 to 5V square wave is a combination of 2.5V DC and 2.5V AC. We can separate the AC component using a capacitor.
Connect SQ1 to A1 directly and to A2 via a 1uF capacitor. Also connect a 100 kOhm resistor from A2 to grond. From the result we can see that the signal at A2 does not have any DC component, it is a -2.5V to +2.5V square wave.
Plotting voltage as a function of time shows the nature of it. If there in no change with time, it is pure DC. Any periodic variation with time represents an AC component. If the average value is ero then it is pure AC, otherwise it is a combination of both DC and AC.