Step Up DC/DC converter noise
Place RC lowpass filter on output of your power supply: 100 ohms and 100uF.
This is a 0.01 second time constant, -3dB at 16 Hz, -20dB at 160Hz, -40dB at 1,600Hz, -60dB at 16,000Hz.

So use your scop probe across the 100 uF capacitor. CLip the scope probe GND
lead to -side of the 100uF, and clip the probe tip to +side of the 100uF.

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Note the ESR and ESL will limit the far-out attenuation.

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That first screen shot shows 14 uS periodic ripple, or 70KHz.

A 0.01 second TAU RC LPF, at 15Hz F3dB, is 5,000X slower, thus might ultimately
produce 5,000:1 cleaner voltage.