LIN155 Oscilloscope - PDF

Oscilloscope LIN155 – Electronic Lab & Instrumentation Techniques School of Electronics and Mechanical Engineering Technology (SEMET) Textbook references: Chapter 16 p. 314 Chapter 18 p. 354 Agenda Oscilloscope Use Voltage Signals Properties of Signals Contr...

Oscilloscope LIN155 – Electronic Lab & Instrumentation Techniques School of Electronics and Mechanical Engineering Technology (SEMET) Textbook references: Chapter 16 p. 314 Chapter 18 p. 354 Agenda Oscilloscope Use Voltage Signals Properties of Signals Control Panel Vertical Gain & Vertical Shift Horizontal Gain & Horizontal Shift Triggering Steps to Find an Input Signal 2 Oscilloscopes – Analog or Digital Oscilloscope is a type of electronic test instrument Draws a graph of an electrical signal, called a “waveform” Waveform: varying signal voltages as a function of time Analyze waveform properties such as amplitude, frequency, rise times, time intervals, distortion, etc. Image source: https://3.imimg.com/data3/SD/IB/MY-691775/analogue-oscilloscope-500x500.jpg Image source: https://i.ytimg.com/vi/uYYLtwFyvns/maxresdefault.jpg 3 Voltage Signals on 2D Graphs Many electronic signals are periodic and repeat constantly eg. sound waves, heartbeats, generators Convert wave to voltage, display how it changes over time 2D graphs are traditionally 10 x 8 intervals: 4 2D Graph Properties Allows you to observe voltage signals over time: V/t graph Use the controls to effectively scale the signal in both directions Y direction = up/down = signal amplitude (strength) X direction = left/right = signal time (or frequency) AMPLITUDE TIME 5 Reading Properties of a Signal Let the blue “signal trace” be a function generator’s output. Determine the amplitude and period from the graph. Each box is a measurable interval: PEAK-TO-PEAK AMPLITUDE y-axis: V/ div x-axis: t/ div PERIOD 6 Oscilloscope Control Layout Horizontal Shift Run/Stop Horizontal Gain Trigger Cursors Selector Selector Measure Vertical Gain Ch1 or Ch2 Vertical Shift Ch1 or Ch2 Image source: https://www.keysight.com/us/en/assets/7018-02749/product-fact-sheets/5990-6679.pdf 7 Vertical Gain Scales the signal in the vertical axis (stretch or compress) Rotate the knob to change the V/div display of the signal Press the knob to toggle the Coarse or Fine adjustment Use Coarse control and STRETCH or maximize the signal COMPRESS inside the graph. Y-AXIS 8 Vertical Shift Moves the signal along the vertical axis (shift up or down) Rotate the knob to shift the position of the signal Press the knob to align the signal with the “zero” position PHYSICAL SHIFT Y-AXIS 9 Horizontal Gain - Timebase Scales the signal in the horizontal axis (stretch or compress) Rotate the knob to change the t/div display of the signal Press the knob to toggle the Coarse or Fine adjustment Use Coarse control and show one or two cycles of the signal. STRETCH or COMPRESS X-AXIS 10 Horizontal Shift Moves the signal along the horizontal axis (shift left or right) Rotate the knob to shift the position of the signal Press the knob to align the signal with the “zero” position PHYSICAL SHIFT X-AXIS 11 Trigger Starts drawing the waveform at a set voltage level Rotate the knob to shift the voltage level of the trigger Press the knob to align the signal with the “zero” position Set trigger at max +ve peak decreasing Set trigger at zero position increasing 12 Oscilloscope – Find Signal Input 1) Turn the power on. It may take a short while to fully boot up. 2) Apply the signal. Select Channel 1 or 2 to light up. Check connection to circuit. 3) Find the signal trace. Click “Default Setup”. Click each knob for trigger, horizontal, and vertical gains to set to zero positions. If it is enabled, you can select the “Auto Scale” button to automatically do this step. 13 Oscilloscope – Set Gains 4) Set the Voltage divisions. Rotate vertical gain to maximize viewing the signal amplitude. eg. Graph is 8 intervals high. If waveform has 4 Vp-p amplitude, set the vertical gain to 2 V/div. The entire amplitude height should be visible within 5 to 8 intervals. 5) Set the Timebase divisions. Rotate horizontal gain to display 1 or 2 full cycles of the signal. eg. Graph is 10 intervals wide. If period of signal is 200 ms, set the horizontal gain to 20 ms/div or 50 ms/div. 14 Oscilloscope – Set Triggering 6) Adjust the trigger, if desired. Set the trigger type (rising-edge, falling-edge). Rotate knob for desired trigger voltage level on the signal. eg. If an LED lights up once per minute, set to trigger at 1 V rising-edge. 7) Adjust the controls for the best image. With a stable waveform in place, you may wish to use the Fine adjustments on the vertical and horizontal gains to zoom in. Note: This maximizes the signal displayed on the screen but it increases the difficulty in estimating signal properties like amplitude or period. 15 Questions 16 Works Cited Electronics Notes – How to use an oscilloscope: http://www.electronics- radio.com/articles/test-methods/oscilloscope/how-to-use-oscilloscope.php Keysight Technologies – Keysight Oscilloscopes: http://www.keysight.com/en/pcx-x2015004/oscilloscopes Image source: https://www.amazon.ca/Kuman-Oscilloscope-Source-15001K-pre-soldered/dp/B01N6PUX70 17