1. Some Concepts from the Labs RC Filter and LabVIEW lab Function generator and internal resistance Root-Mean-Square (rms) value of a sinusoidal voltage Oscilloscope 10:1 probe as a voltage divider 5 Oct. 2004

2. High-pass first-order RC filter

4. LabVIEW front panel LabVIEW Block Diagram

5. Function Generator and Internal Resistance The function generators in the lab have an internal resistance (think “Thevenin resistance) of 50 ohms. Their output voltage indication is calibrated assuming that you have a 50-ohm load connected. So if the indication of amplitude says 1 volt peak- to-peak, what is the actual open-circuit zero-to-peak output voltage?

6. Root-Mean-Square (rms) value of a sinusoidal voltage It is usual in discussing sinusoidal voltages to refer to the effective value of the voltage – the voltage of a DC source that would produce that same power dissipation in a resistor R as the Sinusoidal voltage would. This effective voltage is called the root-mean-square (rms) voltage, V rms. Your text (Hambley, 3 rd ed.) goes through the analysis on pp. 191-3 to show that applying this condition on average power dissipation yields the result For example, if Vrms for the 60 Hz voltage at an outlet in a house is 120 volts, the peak value of the sinusoidal voltage is 170 volts.

7. Oscilloscope Probe as a Voltage Divider Your 10:1 oscilloscope probe is designed to protect the ‘scope from having too high a voltage presented at its input. The probe contains a 10:1 voltage divider that reduces the voltage at the probe tip to 1/10 th of the voltage at the tip, which then appears at the input to the ‘scope. (Note: This means that the 10:1 probe can’t be used as if it were an ordinary cable to connect pieces of equipment.)