I have a Tek 2445A, into which I am feeding two sine waves; 1000hz X, 1002hz Y. When I feed them and observe in X-Y mode, as well as the pretty rotating circle, I have an intense diagonal line, heading from bottom-left to top-right:
I know this must be something mega simple, but this 'scope is SO new to me, with so many knobs and doo-dahs... help?
Well the diagonal line would show up if the sine waves were equal in frequency. The rotating circle happens when they're not in sync (frequency differences). It looks like you're at just that point where it's close enough to show the line but different enough to display the rotating circle....
What happens if you play a 1khz sine wave through through both channels? Do you see just the straight line?
Well the diagonal line would show up if the sine waves were equal in frequency. The rotating circle happens when they're not in sync (frequency differences). It looks like you're at just that point where it's close enough to show the line but different enough to display the rotating circle....
What happens if you play a 1khz sine wave through through both channels? Do you see just the straight line?
That makes me think there is another signal that shouldn't be there. Perhaps it's picking up mains hum on both channels? Are you using actual probes, or just headphone wires? You're probably getting some interference from somewhere else.
Using a computer sound card really isn't the best way to generate signals for a 'scope. I don't think they are ever quite in sync (and in-phase). It's difficult to tell for sure. I suggest you try a function generator instead, if you have access to one.
Okay, so I had the "invert" mode on... oops - with invert off again, I get the single diag line when putting the same freq in both channels, but when putting the frequencies in that are listed in the OP, for the circle, the line re-appears...
Yep, it seems to me two of your signals are equal frequency and in the same phase, but you have another mystery signal of the same frequency but 180 degrees out of phase. That's the only thing I can think of that would give you that X .
Okay, so I had the "invert" mode on... oops - with invert off again, I get the single diag line when putting the same freq in both channels, but when putting the frequencies in that are listed in the OP, for the circle, the line re-appears...
Haha yup, that would explain the backwards diagonal line.
Still not sure why you're getting a diagonal line AND a rotating circle though. What are your scope knobs set to? (hint: A photo would be great here as well )
Haha yup, that would explain the backwards diagonal line.
Still not sure why you're getting a diagonal line AND a rotating circle though. What are your scope knobs set to? (hint: A photo would be great here as well )
Just plug the probes into channels 3 and 4 and turn them on instead of channels 1 and 2. It looks like the volts/div knobs are the same for channels 1&2 and 3&4 (an interesting setup, if that is the case), so you shouldn't have to adjust them.
Just plug the probes into channels 3 and 4 and turn them on instead of channels 1 and 2. It looks like the volts/div knobs are the same for channels 1&2 and 3&4 (an interesting setup, if that is the case), so you shouldn't have to adjust them.