Oscilloscope noob

[Charlie86]

Hi,

Like I mention I am total noob in using Oscilloscope. Just bought Rigol DS1054Z to start learning. When I attache probe to point for probe calibration and press auto button I get nice square signal. But if i press auto button without probe attached to test point I get some noise signal. Is this normal?

https://imgur.com/a/lMYNK

[Paul Moir]

Yes.  When you press the Auto button the 'scope tries to detect what signal is present on the probe and adjust it's parameters to show you a display of it.  If it's only detecting noise, that's what it will display for you.

If you look closely at your two pictures, you'll see the top one has the horizontal timebase at 100us (micro seconds) per division while the second one is at 5.00ms per division.  That's a clue that they're completely different signals. 

[Charlie86]

Thank you very much for yours information.

[David Hess]

The second signal looks like interference from a 50 Hz TRIAC phase control dimmer.

[Charlie86]

Not shure about Triac interference, like I said I am beginner. 

Have to more questions. What is default pass and user for web interface and what is best programs to communicate with oscilloscope.

Thank you

BR

[David Hess]

Not shure about Triac interference, like I said I am beginner.

Do you have a light dimmer somewhere nearby?  If so, try adjusting it while watching that waveform on the oscilloscope.

[Charlie86]

I have 3 led bars under it, but even if I unplug them, noise is still on display.