The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

The New Hotness

  • 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 …