Help reduce noise on USB oscilloscope.

The noise is not present when you run scope on battery ?

Got a scope pic of noise, and FFT pic of the noise spectrum ?


Regards, Dana.
 
crutschow said:
Under what conditions do you see this noise?
Click to expand...
Without the probes plugged in there's no problem, but with the probes there's noise(pic one) and shorted with a 15nF cap (pic two) there is still noise. It's a Hantek 6022BE USB scope.
 
Last edited:
So now instead of USB isolation I need to filter out that 60KHz sine wave between the charger and the laptop. It's too bad these laptop chargers don't come apart easy, I'd take a look and improve.
 

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All leads and grounds as short as possible.

Use polymer for bulk cap, and ceramic disk :




Regards, Dana.
 
Lightium said:
Without the probes plugged in there's no problem, but with the probes there's noise(pic one) and shorted with a 15nF cap (pic two) there is still noise. It's a Hantek 6022BE USB scope
Click to expand...
Unterminated probes tend to pick up noise from the either.
Do you see the noise when measuring circuit voltages?

Filtering may not help, since you are seeing radiated noise.
 
crutschow said:
Unterminated probes tend to pick up noise from the either.
Do you see the noise when measuring circuit voltages?

Filtering may not help, since you are seeing radiated noise.
Click to expand...
Problem was solved when I unplugged the laptop from the charger.
I did have an idea to put a 420uF cap between charger and laptop.
from this site: https://makingcircuits.com/blog/calculate-filter-capacitor-smoothing-ripple/

I get:
C = I / (2 x f x Vpp)
where I = load current
f = input frequency of AC
 
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