# 1X or 10X Passive Voltage Probe?

1. Jul 8, 2010

### vze3bbyp

Hi All,

Suppose you have applied 800kHz, 30ppV sine signal (from a pulse generator) to a 115pF, 10Ohm RC circuit and you want to know the value of the applied voltage as accurate as possible what passive voltage probe would you use, 1X or 10X? Is there a way to check the accuracy of the two measurements? What I do is I use a resistor of known resistance and I divide the current passing through it into the voltage across it measured alternatively with the 1X and the 10X probe. What I see is that throughout one period of the sine wave the 1X probe sustains an R value closer to the known R value than the 10X probe. This makes me conclude, although I'm measuring the voltage across the R and not the voltage across the RC, that the 1X probe is more accurate. Am I right and are there other ways I can objectively check the accuracy of the two probes with regard to measuring the voltage across the RC?

2. Jul 9, 2010

### Staff: Mentor

Welcome to the PF.

The Tektronix 'scope probe primer should be useful reading for you. It is available at this Tek tutorial page:

http://www.tek.com/learning/oscilloscopes/

You need to register to download it, but the registration is free.