4.3 Basic Operation of Oscilloscope

1. The first things that is noticed on an oscilloscope is the large display that is used for displaying the waveform. This typically may take around a quarter of the space on the front panel or even a little more. It is often good to have a reasonably large display then it is easier to see the various elements of the waveform.

1. There is a variety of different connectors on the front panel. Typically there is an input for each of the channels to be displayed - often an oscilloscope will have more than one channel. Many oscilloscopes are dual channel and can therefore display two signals at the same time, allowing waveforms to be compared. Other inputs may include a trigger input that will enable the trace on the oscilloscope to be triggered according to this signal.

There is a variety of controls on the oscilloscope:

· Vertical gain / signal input sensitivity: This is generally calibrated in V/cm, i.e. each vertical division on the scale represents a given number of volts.

· Timebase: This alters the speed at which the trace crosses the screen horizontally on the oscilloscope. It is calibrated in terms of time / division, e.g. 1ms / cm, assuming the divisions are at one centimetre intervals.

· Trigger: The controls that are associated with the trigger enable the timebase of the oscilloscope to be triggered in various ways. This enables a still or stable picture to be obtained on the screen of the oscilloscope.

1. Set the BK 4040 to generate a sine wave, set the frequency to 50 Hz, and using a

voltmeter set the output voltage to 1 volt peak.

2. Connect the output of the BK 4040 to one of the inputs of the Agilent Oscilloscope.

3. Set the Oscilloscope to a Timebase of 10 ms and vertical scale to 0.5 volts/division.

4. How many cycles of the sine wave appear? How many peak-to-peak divisions does

the sine wave fill? Are you seeing a 1 volt peak 50 Hz sine wave? If so, continue.

If not, check your function generator and oscilloscope settings and repeat this step

until you obtain the proper signal display.

5. Change the Timebase to 1ms. What happens?

6. Change the vertical scale to .1 volts/division. What happens?

7. Describe what happens as one decreases and increases the Timebase.

8. Describe what happens as one decreases and increases the vertical scale.

9. Repeat steps 1-8 using a square wave and triangular generated by the Function

Generator.

10. When satisfied turn off both the function generator and the oscilloscope.