An oscilloscope is a far more powerful instrument than a bargraph indicator or even a voltmeter. It can show you the time dependence of the signals in your circuit. The EWB oscilloscope provides a fairly close approximation of a real one. It has two independent input channels, A and B, an input for an external trigger and a ground connection
To look at the output of your signal generator you can add an oscilloscope to the circuit you just made.
1. Drag the oscilloscope onto the circuit window, and double-click on it. The oscilloscope has four terminals, for two independent input channels, a trigger input and a ground connection. The input channels sense voltages with respect to ground! As long as there is at least one ground terminal attached to your circuit, it is not necessary to connect the oscilloscope ground. We will discuss the issue of how the oscilloscope is triggered in class. At this point, leave the triggering on auto.
2. Connect channel A to the '+' output of the function generator, and activate the circuit. You should now have a sine wave on your oscilloscope screen.
3. Make drastic changes in the signal amplitude and frequency, and adjust the sensitivity and time base settings such that you still maintain an easily interpretable picture of the wave form on the oscilloscope screen. It may be necessary to occasionally reactivate the simulation.
4. Change the "y position" such that the trace comes back on center. This can always been done as long as the offset is not too large. (Most oscilloscopes cannot produce an internal offset that is much larger than the full scale display range.)
5. Change the "y-position" back to zero, and select "AC" as input coupling mode. In this mode the DC component of the signal is removed. The EWB oscilloscope is very good at this, but real instruments have a difficulty distinguishing between DC and very slowly oscillating signals. In practice, avoid the AC input mode for signal frequencies less than 100 Hz. To get a larger image of the oscilloscope, try the expand button. On the expanded display you will find two vertical line cursors. By moving these around you can measure time and amplitude of points on the displayed traces.
