When the sync switch on a 'scope is set to the channel you are using then it takes the signal you are viewing, squares it with a Schmitt-trigger and uses the resulting pulse to sync the horizontal oscillator in the 'scope.
Only on a solid state O scope , it uses schmitt triggers , not on a tube O scope
A Tube O scope uses Tubes to do the pulsing , the horizontal oscillator is a tube circuit also
Only if the waveform inject into the channel is related to ground and not floating
If the waveform is floating the horizontal oscillator in the scope wouldn't know what to do , that's why the waveform is free running
60Hz has nothing to do with it unless the sweep and its sync is set for LINE! Line is the 60Hz electricity line.
How do you tell if the circuit is a line-powered and line-synchronized circuits?
A line synchronized circuit has to use the LINE triggering at 60hz
How do you tell on a schematic that the circuit is a line synchronized circuit?
The viewed signal is used to sync the horizontal sweep oscillator
True I agree
The viewed waveform is squared into pulses then the pulses sync the horizontal sweep oscillator.
True , I agree
Only on a solid state O scope , it uses schmitt triggers , not on a tube O scope
A Tube O scope uses Tubes to do the pulsing , the horizontal oscillator is a tube circuit also
Maybe the sync trigger switch on your 'scope is labelled SOURCE (of the sync). Then when it is set to channel #1 the sync comes from the squared signal viewed on channel #1.
No, My O-scope has a SOURCE mode , you can Source channel#1 or Channel#2 to eachother or to the triggers input
example:
You can have a sync signal on Channel#2 which you can uses as your Reference or external sync signal
You can SOURCE channel#1 to Channel#2
So that Channel#1 waveform is triggered by channel#2