Question about using Portable power bank or Laptop
Posted: Mon Jan 07, 2019 6:27 pm
When I power my dso 138 mini using a portable power bank or my laptop, when I touch the Pos probe to my finger, no wave is shown. But when I plug it into the wall outlet, it shows the wave when I touch my finger on the red probe. This is what Im referring to -> https://imgur.com/a/JnNmYO6 However, connecting the probe to 1 kHz test signal shows the wave on all 3 power sources. Why is this? Have a feeling it has to do with ground somehow.