# How can I plot Z for a set of chokes?

1. Apr 27, 2014

### hobbs125

Hello everyone,

I need to find a way to measure and plot the impedance of a set of chokes across a frequency range of 10kHz. Any ideas how I can do that? I have a frequency generator, a variable power supply and an oscilloscope with a spectrum analyzer.

2. Apr 27, 2014

### Staff: Mentor

If you just need the Z at 10kHz, then there is no frequency range involved. What is the equation for Vout/Vin for an RL circuit? How can you apply that now?

3. Apr 27, 2014

### hobbs125

I want to actually measure the impedance from 30-40 kHz and plot it against the frequency.

4. Apr 28, 2014

### Staff: Mentor

Then just use an RL circuit. Put your oscilloscope probe #1 at the output of the signal generator before the R, and probe #2 between the R and L (far side of L goes to ground). Work out the math for the attenuation and phase shift versus frequency, to help you choose a good value of R for a given L.

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