Oscilloscopes HP 54600 B Digital Oscilloscope Alex Jones

Oscilloscopes HP 54600 B Digital Oscilloscope Alex Jones COE 0501 University of Pittsburgh

Safety Tips Protect Yourself: Avoid contact with Voltage or Current Sources • Use shrouded test leads and alligator clips. • Leads: Connect to oscilloscope first; Connect/disconnect at source so loose lead is dead. • Connect probe to ground before connecting to high. Protect the Scope: • 400 V maximum on input. • Use probes to reduce high voltages. • Be familiar with user’s guide. University of Pittsburgh

Oscilloscopes display the relationship of Voltage vs. Time waveforms for analog and digital signals. The display is like a dynamic plot. Therefore we must be able to adjust the scales and offsets of the “plot” of the waveform. • Voltage - set the Input / vertical scale factor • Time- set the horizontal / time scale factor • Position (Vertical and Horizontal) • Triggering - when should it start to draw? • Storage - keep a copy • Measurement - measure features of the waveform University of Pittsburgh

Front Panel Features Horizontal Position Measurement Cursors Save/Recall Storage Autoscale/ Display/Print Triggering Vertical Scale Vertical Position Intensity Ground Calibration University of Pittsburgh Inputs Power External Trigger Horizontal Scale What’s wrong with this picture?

Task - Front Panel l Draw a picture in your lab notebook of the front panel of your scope. l Every button, knob, and connector should be depicted and labeled. l Use an entire page of your lab notebook for this. University of Pittsburgh

Task - Front Panel l On the next page of your notebook, make a list of the buttons, knobs, and connectors on the front panel. l As you learn about each item in the list, write a brief description of it in your notebook. University of Pittsburgh

Power Switch • This switch turns the oscilloscope on and off. University of Pittsburgh

Intensity Knob • This knob adjusts the brightness of the display • If no trace is seen, it may be because the intensity knob is set too low. University of Pittsburgh

Ground Connection • This connection may be used to ground probes. University of Pittsburgh

Signal Inputs • These connections are used to connect coaxial cable, probes, etc. to the oscilloscope. • The outside of the connector is grounded. University of Pittsburgh

Connecting a Signal • Make sure the input voltage level £ 400 V. • Connect a BNC cable or a probe to a channel input. • Connect the other end of the cable or probe to the device to be measured. University of Pittsburgh

Task - Calibration Signal l Connect a probe to channel 1. l Connect the red lead to the calibration signal below the display. l Push the Auto-scale button. l Draw a picture of the resulting waveform in your lab notebook. University of Pittsburgh

Vertical Section addition menu volts per division channel menu position knob University of Pittsburgh volts per division channel menu position knob

Input Selection • Use the push buttons to enable/disable each channel. • These also enable the “soft keys” under the display University of Pittsburgh

DC vs. AC Coupling • For digital signals we almost always want DC coupling. • AC coupling centers the signal on 0 v • Digital signals swing between 0 v and 5 v DV University of Pittsburgh

Vertical Scale • Use the vertical volts/div knobs (located above the channel input connector) to scale the signal vertically on the screen. University of Pittsburgh

Task - Calibration Signal l Adjust the volts/div knob so that the entire calibration waveform is visible on the screen, and appears as large as possible. l Record the volts/div setting in your lab notebook. l Use the scope to measure the amplitude of the calibration waveform. University of Pittsburgh

Vertical Positioning • Use the vertical position knob (located above the channel input connector) to position the signal vertically on the screen. University of Pittsburgh

Horizontal Section delay knob main/delayed menu time per division University of Pittsburgh

Time Base • Turn the time/div knob to adjust the sweep speed (time base). • The sweep speed has a range from 2 ns to 5 s. University of Pittsburgh

Task - Calibration Signal l Adjust the time/div knob so that one period of the calibration waveform is visible. l Record all time base parameters in your lab notebook. l Use the scope to measure the period of the calibration waveform. l Compute the frequency of the waveform. University of Pittsburgh

Horizontal Positioning • Use the delay knob to move the signal horizontally. • Note the value displayed on the status line. University of Pittsburgh

Trigger Section source menu trigger level knob mode menu slope/coupling menu University of Pittsburgh holdoff knob

Triggering Source Menu • Use this menu to assign a trigger source. • The choices are line, CH 1, CH 2 and external. University of Pittsburgh

Triggering Mode Menu • Use this menu to choose a trigger mode. • The choices are auto level, auto, normal, single, and TV. University of Pittsburgh

Triggering • Use the level knob to set the trigger voltage. • The screen will display the trigger level in inverse video and a horizontal line representing the trigger location. University of Pittsburgh

Triggering 1 Delay Triggering level + Slope - Slope University of Pittsburgh

Custom Features Autoscale Voltage menu Time menu Cursor menu Storage Delay University of Pittsburgh

Custom features time menu setup menu voltage menu trace menu autoscale display menu University of Pittsburgh cursor menu cursor knob print/utility

Auto Scale • Sets the Time Scale and Vertical Scale £ for all inputs • Uses the highest active channel (1, 2, 3, 4, ext) as trigger University of Pittsburgh

Voltage Menu • Use this menu to make automatic voltage measurements. • Measurements include peak to peak voltage, rms voltage, max voltage, etc. The choice is made using the softkeys below the display. University of Pittsburgh

Voltage Readings Vp Vrms time Vrms = 0. 707 Vp (Sine wave) University of Pittsburgh Vpp

Time Menu • Use this menu to measure frequency, period, duty cycle, risetime, etc. University of Pittsburgh

Frequency and Period T f= 1 Hz T w = 2 × p × f rad/s (t ) time University of Pittsburgh

Cursor Menu • This menu brings up a list of cursor commands and activates the cursor knob. • The cursors can be used to measure specific voltages, times, etc. University of Pittsburgh

Storage • These buttons control the storage features of the scope. • Run, Stop, Auto-store, Erase • Save, Recall University of Pittsburgh

Storage • Run - Normal operation • Stop - Keep the most recent trace, do not overwrite • Auto-Store - Keep overwriting traces, with dim lines • Erase - Erase all traces Save/Recall • Trace - Can store 2 “screen dumps. ” Brings up soft keys • Settings - Can store scope settings for reuse University of Pittsburgh

Delay • This button enables the use of two time-bases for the same signal • This gives the ability to have a global and zoomed picture of the waveform at the same time. • It enables a soft key menu (XY, Vernier, Time Ref) University of Pittsburgh

Storage • Run - Normal operation • Stop - Keep the most recent trace, do not overwrite • Auto-Store - Keep overwriting traces, with dim lines • Erase - Erase all traces Save/Recall • Trace - Can store 2 “screen dumps. ” Brings up soft keys • Settings - Can store scope settings for reuse University of Pittsburgh

End of Scope Presentation University of Pittsburgh