Reducing Error in Displaying vC(t) & vL(t): Tips for Lab 5 Procedure

[Turion]

Lab 5 asks: what is the “inherent” error in our procedure for displaying both vC(t) & vL(t)? How would you go about reducing the effect of this error?

If you look at figure 5.3 on page 41, you will see that the oscilloscope connects one end to node A and the other end to ground. Therefore, the error is that you are not measuring the voltage waveform across the capacitor. You are measuring the voltage waveform across the capacitor and the 20 ohm resistor, right? Can't you just put both ends of the oscilloscope on both ends of the capacitor?

 

[milesyoung]

Can't you just put both ends of the oscilloscope on both ends of the capacitor?

I assume from your attachment that you're using single-ended probes, i.e. one of the "ends of the oscilloscope" is the probe ground clip? You're going to short out the capacitor/inductor and/or the current sense resistor depending on what end you attach the ground clip to.

For a differential measurement of the capacitor/inductor voltage, subtract 'channel 2' from 'channel 1'. Digital scopes often have this functionality.

 

[Turion]

I assume from your attachment that you're using single-ended probes, i.e. one of the "ends of the oscilloscope" is the probe ground clip? You're going to short out the capacitor/inductor and/or the current sense resistor depending on what end you attach the ground clip to.

For a differential measurement of the capacitor/inductor voltage, subtract 'channel 2' from 'channel 1'. Digital scopes often have this functionality.

Haha. Thanks man! This helped me a lot! =]