UNIVERSITY OF CALIFORNIA AT BERKELEY College of Engineering Department of Electrical Engineering and Computer Sciences EE105 Lab Experiments HP 54615B Oscilloscope Tutorial Contents 1 Introduction 1 2 Quick Notes to get started fast 1 3 Triggers 2 4 Interface Details 4 1 Auto Scale Button 4 2 Vertical Section 4 3 Horizontal Section 4 4 Display Button 4 5 Measure Section 4 6 Cursors 2 2 3 3 4 4 5 5 Examples 5 1 Measuring Vp p of a Waveform 5 2 Measuring Frequency of a Waveform 5 3 Measuring Voltage with Cursors 5 4 Using Averaging 5 5 Measuring a Transfer Characteristic 5 6 6 6 6 6 1 Introduction The HP54615B is an oscilloscope used primarily to measure voltages that vary with time There are two independent in put channels which can be used simultaneously to measure and compare two waveforms e g input and output waveforms for a filter The default mode on the oscilloscope will plot time on the horizontal axis and voltage on the vertical axis The scaling of each axis can be controlled independently for each input Scaling can either be done manually or with the Auto Scale button There are other modes of operation for the oscilloscope such as the XY mode in which one channel is plotted against the other in a Voltage Voltage plot but in these labs you will primarily use the default mode This tutorial starts with quick notes on the most vital information so if you feel somewhat familiar with oscilloscopes you can check over the quick notes and figure out the details on your own The later sections include more detailed descriptions of the HP54615B interface and some examples of common measurements 2 Quick Notes to get started fast After connecting the probes try the Auto Scale button It will generally provide a good axis scaling if the waveform is not too irregular small or high frequency 1 3 TRIGGERS 2 Each channel has vertical scaling controls to manually set scaling You can see the current axis scaling at the top left of the screen generally in volts per division and adjust the scaling with the knobs in the Vertical section There is one vertical scaling knob per input channel Measure signals e g Vp p by pressing the appropriate button in the Measure section of the panel e g Voltage and then selecting the appropriate value to measure from the menu buttons beneath the screen Cursors can also be placed with the Cursor button menu buttons beneath the screen and the knob next to the Cursor button AC coupling will remove any DC bias offset from the measured signal Coupling can be selected with the menu buttons beneath the screen The oscilloscope s ground is earth ground so the black alligator wires on the oscilloscope probes are connected together Since the function generator is also earth grounded the oscilloscope probe grounds are connected to the function generator ground To avoid shorts to ground you should always connect the oscilloscope ground clips to the same node Do not try to use the probes to measure floating signals as you can with the DMM 3 Triggers The HP54615B has a Trigger input section on its interface panel Triggers are used to synchronize oscilloscope timing with an external signal so that measurements can be taken at the correct time For example to capture a single voltage pulse one might use a trigger input to signal the oscilloscope to take measurements at the pulse arrival Triggers can also be used with periodic inputs Generally you will not need to use oscilloscope triggering in these labs 4 Interface Details The power button is in the lower left corner of the front panel The oscilloscope screen displays measurement axes At the top of the screen vertical and horizontal scaling units are displayed The default mode will display vertical scaling for each input in volts div and horizontal scaling in seconds div where the corresponding divisions make up the grid of squares on the screen The buttons beneath the screen are referred to as menu buttons or context buttons in this tutorial Their functionality changes with other button pushes e g by pushing the Measure Voltage button Each button s current function is labeled on the screen by the text immediately above the button These menu buttons are essential to taking measurements and performing more complex functions on the oscilloscope This tutorial will describe the sections of the front interface panel in the general order you would consider them to take a waveform measurement after pressing the Auto Scale button At the end of the tutorial there are examples of common measurement procedures There is a photo of the HP54615B front panel in Figure 1 4 1 Auto Scale Button The Auto Scale button has the oscilloscope guess a good axis scaling based on the input waveform on each channel This button is always a good first pass for scaling and often will be all the scaling that you will need You can tune the scaling manually with the Vertical and Horizontal controls described below 4 2 Vertical Section The vertical controls adjust the scaling and position of each independent channel display The controls for each channel are aligned vertically with each input port 4 3 INTERFACE DETAILS Figure 1 HP54615B Front Panel The Volts Div knob sets the vertical scaling vertical zoom on the display The 1 and 2 buttons toggle showing their respective inputs The position knob controls the voltage offset against the display axes The horizontal axis does not represent 0 volts but instead the 0 volt position for each input is designated by a numbered ground symbol on the right of the display When you adjust the offset with the position knob you will see the corresponding channel s ground symbol move vertically The Math button can combine inputs with one of the following arithmetic operators addition subtraction or multiplication The operation can be selected with the menu buttons beneath the screen after pushing the Math button When using the Vertical control section e g after pushing 1 or 2 the menu buttons beneath the screen show a menu with various options related to the probe inputs The list below assumes that the 1 button has been pushed Menu 1 1 ON OFF Toggles the display of input 1 Input 50 1 M Toggles the input impedance to the channel input Should usually be set at 1 M Coupling DC AC ground Sets the coupling for the channel input DC will show both DC and AC values AC will only give time varying voltage values and remove any offset and ground will set it as a virtual ground BW Lim Off On Leave this at default Vernier Off On Leave this at
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