Oscilloscope Tutorial | How to use an Oscilloscope

Oscilloscope Tutorial

Here is my attempt at an Oscilloscope Tutorial without you being physically present in front of me. It is usually far easier to demonstrate these things then to put pen to paper. As a once-upon-a-time college professor it was a very common dilemma teaching students how to use the oscilloscope.  It is a strange and interesting instrument to them because it is very visual and has lots of “knobs” to tinker with! But, the students would ask how to use it and what to do with the images found on the screen. Once the magic of visual representation was understood the scope became their favorite tool in the laboratory.

Simple oscilloscope tutorial on how to use the oscilloscope scope for general purpose applications.

This is a simplified view of the basic oscilloscope instrument:

Simplified Oscilloscope

Oscilloscope Tutorial – The ‘nitty gritty’ details

The sine wave on the graphic screen is what would be seen when looking at the waveform of a pure sine wave generator.   The squares on the graph would be calibrated to volts/division and, therefore, the graphic presentation can be used as a voltmeter.

The red “vertical” knob is to select the range or sensitivity of the measurement being taken.  If  the test signal were coming from the AC outlet of the house power system, for example, the peak voltage would be about 120v times 1.4 for the peak, or about 168 volts.   Thus, if the vertical knob were turned to choose 20v/division the screen be able to display the positive and negative peaks of the 120v rms sine wave.

The other red knob marked “time base” is the adjustment for setting the rate at which the beam sweeps across the screen.  It is calibrated for seconds/div or milliseconds/div and is used to allow a full set of cycles of the test signal to be seen.   Remember the time period of an alternating signal is the reciprocal of the frequency or T = 1/f.  In our example if the sine wave is a 60Hz voltage then the time for one cycle is 1/60 or about 17 milliseconds.  Therefore, the time base setting would be selected accordingly. The small red knob marked “trigger” is an adjustment which alters the level on the circuits inside the oscilloscope to set the level of the voltage of the sweep circuit will trigger the sweep.   Adjusting it can alter when on the sine wave you want the horizontal sweep to begin. The “X” and “Y”  connection points are where the probes or connection leads will be inserted.

The “X” probe lead usually connects to the ground or earth of the circuit or voltage under test whilst the “Y” probe lead connects to the voltage point in the circuit under test. By counting the time divisions within a full cycle of the sine wave the frequency can be calculated.

Many oscilloscopes have two or more vertical inputs and can show two or more signals simultaneously.  Below is shown a dual trace oscilloscope with two vertical inputs and two signals of different frequency being shown.

Dual Trace Oscilloscope

There are many more applications and variations of oscilloscopes but this is a starting point for those new to this kind of electronic instrument.

Note: Images from http://www.ibiblio.org/kuphaldt/socratic/output/scope1.pdf

Thanks for reading this oscilloscope tutorial!

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