What is the TRIG.SOURCE button for?

[M. next]

This button as I far was informed is located on the oscilloscope. What is it for (my experiment is frequency comparison to find Lissajous curves)?
How does it look like (I have never noticed it).

Thanks

 

[Studiot]

On any instrument (pulse generator, scope etc) with a trigger the trig.source switch selects the source.

The source of the trigger signal may be internal or external.

On a two channel scope the usual arrangement is for a button to select between triggering from ch1 and ch2.

The idea of the trigger is to run the sweep across the screen in synchronisation with the signal to get a good steady display. So the rising input waveform is arranged to start (trigger) the beginning of the horizontal sweep.

You do not want this for lissajous figures - you use the scope in X -Y mode for that.

 

[M. next]

Oh thanks :) That was helpful