Usage of Oscilloscopes

Oscilloscopes

• Oscilloscopes normally have two inputs so that two different electrical signals can be measured at a time. There are a number of controls on an oscilloscope and the most important are the volts/division control and the time/division control. The volts/division changes the vertical scale on the screen and the time/division changes the horizontal scale on the screen.

Measurements of AC Frequency

• Sometimes it is important to verify the frequency of an electrical signal. This can be done with an oscilloscope in the following way. The electrical signal is plugged into one of the inputs and the oscilloscope is switched on.The volts/division is varied until the signal is within the vertical limits of the screen, and the time/division is varied until a clear oscillatory waveform is seen. The number of horizontal divisions between peaks is measured. The number of horizontal divisions is multiplied by the time/division setting to get the period. The frequency is equal to 1 / period.

Measurements of AC Peak-To-Peak Amplitude

• The amplitude of an AC signal can be measured directly with an oscilloscope. This is done by plugging the input into the oscilloscope, and switching on the oscilloscope. The volts/division and time/division are modified to get a clear oscillatory signal. The number of vertical divisions between peaks and troughs is counted and multiplied by the volts/division to get the peak-to-peak amplitude.

Measurement of DC Offset

• Often electrical signals contain a mixture of AC and DC components. The DC offset value can be measured using an oscilloscope. The oscilloscope is switched on and the trace line centered onto the 0V mark. The electrical signal is plugged into the oscilloscope and the vertical shift in the signal is measured in order to obtain the DC offset.