I may have this completely wrong so please correct my misunderstanding.

Normal scope mode plots volts vertically against time horizontally.
For XY mode you need a 2 channel scope and you plot Channel 1 against Channel 2.
A PC soundcard scope uses the mic as an input and that is a mono channel.
Yet the soundcard scope from Christian Zeitnitz http://www.zeitnitz.de/Christian/scope
has the XY feature. When we use this are we just plotting Y against Y and so will always have a line at 45 degrees to the horizontal whenever the Y volts fluctuates and a pinpoint display if the volts are constant.
If I am correct could the soundcard scope ever be used to really plot X against Y ?
Thanks
Tony

 

Hello,

Most times the mic input is mono with a powersupply ring.
(see the soundcard manual for the exact info).
If you configure the inputs from the line input from the soudcard, you will have two seperate channels.
The left and right channels will be shown as X and Y, so a XY mode is possible.

You will notice that the inputs are usfull for AC signals only.
Also be carefull to have a signal that is to strong for the soundcard.

Bertus