"Arfa Daily"

** When servicing audio, knowing the polarity of the test signal and if
there is significant phase shift is important. A scope triggering off
the incoming wave will it not reveal this in single channel mode - so
AF used both channels.

A much better way is to use the External Synch input on your scope and
link it to a fixed output on your bench audio oscillator ( create on if
you have to). This way, you see instantly if the signal's phase has
reversed or has a large phase shift.

Also, triggering will be rock steady with nearly any kind of distorted,
noisy or contaminated signal on the scope screen.

Try it out for a day or two - you will never go back.



Interesting. Are you squaring up the generator's sine output, to give a
good sharp transition for syncing the scope ?

** FFS - that processing is inside any decent scope.

Supply it with 0.5volt rms sine wave and you are away.


I'll have to look at that on my scope, but off the top of my head, I
thought that the trigger point was still adjustable on external and could
be set anywhere on the trigger signal and if so, I'm not sure that I see
how it helps to trigger the scope externally from the same sine wave as it
would use internally on auto trigger.


** But it is NOT the same sine wave !!!!!!!!!!!!

Various audio devices invert, phase shift, phase modulate and even time
shift sine waves !!!


I can see how it would be helpful to have a fixed trigger point, virtually
at the beginning of a cycle,


** Best set the trigger level to a zero crossing of the generator feed so
the same wave on the scope starts at a zero.

I have mine so the first half cycle is positive when there is no phase
shift.

With external synch, the scope is always triggered and the level on the
screen does not matter.

FFS - TRY IT !!!!!!!!!!!



.... Phil