New oscillioscope help question

[jnkirk71]

Hi I have an entry level Siglent scope I purchased a year ago and sparingly used.
I have had no problem using 2 probes on one breadboarded audio effect.
however whenever I try to compare with another audio effect with its own power supply, one of the probes signals remains visible and the other goes all fuzzy.
when I switch between each channel by turning the other one off , it becomes visable.
Am I missing something? do i need to do some setting to view an LFO on 2 separate devices?

embarrased!

[bdunham7]

What model scope do you have? 

I think you are looking for a function called "Alternate Trigger" and only a few older Siglent models have that.  Without it, unless the two signals have the exact same frequency or are an exact multiple, you can't lock in both signals at the same time.  One workaround is to the the "Single" function which will take exactly one snapshot of each signal so that it is clear.

[jnkirk71]

Oh bugger!
It’s a siglent sds1202x-e

[bdunham7]

That model does not have an alternate trigger feature and cannot be used to view two unrelated or unsynchronized signal simultaneously and continuously.  Try the 'SINGLE' button.

[alsetalokin4017]

Ditto. Here's where you break out the old analog 100 dollar Tek 2213a.... No Honey it's not just a doorstop 

[krzysssztof]

You may also try capturing one channel, saving reference plot in the memory (it is supported by your scope, "REF" function).
Later on you only need to capture 2nd signal and display the previous plot on the same screen.