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Quartz Resonator Test Fixture: Cleanup

Isolating the USB port from the laptop eliminated a nasty ground loop, turning off the OLED while making measurements stifled a huge noise source, and averaging a few ADC readings produced this pleasing plot:

Resonator 0 Spectrum

Resonator 0 Spectrum

Those nice smooth curves suggest the tester isn’t just measuring random junk.

The OLED summarizes the results after the test sequence:

LF Crystal Tester - OLED test summary - Resonator 0

LF Crystal Tester – OLED test summary – Resonator 0

Collecting all the numbers for that resonator in one place:

  • C0 = 1.0 pF
  • Rm = 9.0 kΩ
  • fs = 59996.10 Hz
  • fc = 59997.79 Hz
  • fc – fs = 1.69 Hz
  • Cx = 24 pF

Turning the crank:

CC 2017-11 - Resonator 0 Calculations

CC 2017-11 – Resonator 0 Calculations

I ripped that nice layout directly from my November Circuit Cellar column, because I’m absolutely not even going to try to recreate those equations here.

Another two dozen resonators to go …

 

 

 

 

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  1. 60 kHz Quartz Tuning Fork Resonator Data | The Smell of Molten Projects in the Morning

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