Making a Hardcopy of the Oscilloscope DisplayThe DPO 2014B o

Making a Hardcopy of the Oscilloscope DisplayThe DPO 2014B oscilloscopes in our lab are connected to the computer on the lab bench with aUSB interface cable. Start the program, “OpenChoice Desktop” (Hopefully, you will find it on theDesktop.This is a program from Tektronix that provides a means to capture images and data from theoscilloscope. It will probably be intuitive to you how to capture images.Capture an images using both the 5V p-p output.
Copy the image to the Clipboard, and paste it into a Word Document to turn in with your lab

report.Experiment with how to display and capture images from the scope. (e.g. with and withoutmenus displayed.) This method of capturing figures will be very helpful for future lab reports.You can also save waveform data (from multiple channels) to a file. You may find this useful forfuture analysis of data or making nicer figures using Matlab.Some example images are shown at the end of this document.A Common Pitfall ExposedUse a digital multimeter (DMM) to measure the resistance between the probe black lead (eitherchannel) and “absolute” ground. (As defined by our power outlets in the room.) To do this, usetheground on the breadboard. (You can plug a banana cable into the black output at the top of thebreadboard. Be sure not to plug the cable in to either of the red outlets! Just to be safe, do notturnthe power on for the breadboard.)

Q 1) What can you conclude about what the oscilloscope \"low\" side (probe black lead) is connectedto?________________________________________________________________________

Q2 ) Explain how a carelessly dangling black probe lead could blow out a powered-up integratedcircuit chip:________________________________________________________________________________________________________________________________________________Q3 ) Explain why attempts to use only one input channel of the oscilloscope to make differential, orfloating,voltage measurements will fail:________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Solution

As the name, Voltage Isolator Measurements implies, isolators do not have direct electrical connection between the floating inputs and their ground-referenced outputs. The signal is coupled via optical or split-path optical/transformer means. “Floating” a ground referenced oscilloscope puts all accessible metal including the chassis, casing, and connectors at the same voltage as the test point that the probe reference lead is connected.