Learn how to get the most out of your digitaL osciLLoscope. EDU06 Oscilloscope Tutor Board HEDU06 By Velleman n.v.
Getting started The purpose of this board is to learn how to perform basic measurements with an oscilloscope. Most experiments can be performed with any digital storage scope. Some experiments can be performed with an analog scope. Experiments in this project are performed using the Velleman HPS140 Handheld Pocket Scope. All experiments require basic knowledge of terms such as AC and DC voltage, current, resistance, etc… Make sure to check You Tube as well, it features a short movie for each experiment.
4 Oscilloscope basics Oscilloscope basics Measuring probe: Oscilloscope basics While a multimeter shows an instant voltage level or an average voltage level, an oscilloscope is capable of displaying voltage levels over a period of time. Voltage is displayed vertically (X-axis) versus time (Y-axis). To be able to display waveforms, we need to connect the signal to the input of the oscilloscope. Similar to a multimeter, the oscilloscope uses a measurement lead, but here it is called a ‘probe’.
6 Exp.1: measuring AC voltage Exp.2: Adjustable AC voltage (advantages of the auto-setup function) Experiment 1: Measuring AC voltage 7 Experiment 2: Adjustable AC voltage (advantages of the auto-setup function) Connection layout: NOTES: Connection summary: Connection layout: NOTES: Connection summary: GND clip : 2 Probe tip : 1 GND clip : 2 Probe tip : 3 Purpose: The purpose of this experiment is to display and measure AC voltage.
8 Exp.2: Adjustable AC voltage (advantages of the auto-setup function) Turn RV1 a little further clockwise. The signal goes offscreen and the Vrms readout displays ?????mV, because the unit is no longer capable of calculating the correct Vrms. Measuring AC grid frequency and period 9 Experiment 3: Measuring AC grid frequency and period Connection layout: NOTES: How can we display the current signal correctly again? Increase the V/div setting to 0.1V/div.
10 Rectified AC, single phase Measuring AC grid frequency and period Press the upper right button again to select vertical marker 2. Use the arrow keys to position this marker at the exact same location but further to the right of the screen. 11 Experiment 4: Rectified AC, single phase Connection layout: NOTES: You have now selected one period or cycle of the displayed waveform. In the lower right corner, the unit displays the time between the two markers. In most cases, this will be 20ms (16.66ms).
12 Rectified AC, dual phase Rectified AC, dual phase Experiment 5: Rectified AC, dual phase 13 Now, check what happens when you flip the switch from single phase to dual phase rectification. Connection layout: NOTES: Flip the switch back and forward, to clearly see the difference between both settings. A little theory: As you can see, the ‘interruptions’ we have noticed with single phase rectification are gone. As opposed to single phase rectification, both halves of the sine wave are used.
14 Smoothed versus unsmoothed DC (ripple) Smoothed versus unsmoothed DC (ripple) Experiment 6: Smoothed versus unsmoothed DC (ripple) Connection layout: 15 Can we measure this amount of ripple? Yes we can, a scope is the ideal tool for ripple measurement. Flip SW1 back to single phase rectification. NOTES: Default, your scope starts up with ‘DC-coupling’ selected. Change that to ‘AC-coupling’ (see manual for how-to instructions).
16 DC measurement DC measurement 17 Set the DC reference: Experiment 7: DC measurement Connection layout: To set the DC reference, set the input coupling to GND and wait a couple of seconds, until the DC readout in the lower right hand corner displays ‘0.0mV’. NOTES: If the settings have been performed correctly, your scope will now show a flat trace above the centre of the screen and the readout in the bottom right hand corner will show the measured DC voltage.
18 Waveform with adjustable frequency Waveform with adjustable frequency Experiment 8: Waveform with adjustable frequency Connection layout: NOTES: 19 Exercise: Press and hold the upper right hand button, to enter the menu. Release and press again a number of times until ‘Trg Level’ is highlighted. Wait until unit quits the menu. Now look at the bottom left hand side of the screen, the trigger symbol is displayed. The arrow buttons allow you to shift the trigger level up or down.
20 Glossary Glossary 21 Noise: Undesired random addition to a signal. GLOSSARY Ripple: Unwanted periodic variation of a DC voltage. Signal: Voltage applied to the input of the oscilloscope. The subject of your measurement. 3 Sine wave: Mathematical function that represents a smooth repetitive oscillation. The waveform shown at the start of this glossary is a sine wave. 6 4 8 7 Spikes: Fast, short duration transients in a signal.
1µ R5 10K HPS50: HANDHELD PERSONAL SCOPE WITH USB Powerful, compact and USB connectivity, this sums up the features of this oscilloscope. The large keyboard and bright LCD makes this unit a breeze to use, combine this with great specifications and you wonder how you ever managed without it! A complete function generator in pocket format! Now you can take test signals on the move, 3 waveforms can be selected. Set the output voltage or frequency and select signal waveform using the on the screen menu.
+ The board generates a number of safe ‘real-world’ signals, which we will use to perform measurements. Get familiarized with AC, DC and frequency measurements, sine and square waves, power supply ripple, full and half wave rectifiers, oscillators etc… Learn what terms such as V/div, Time/div, trigger level, auto-setup etc… mean. All experiments featured in this project are performed with the Velleman. Most experiments can be done with any digital storage scope.
