What does the "trigger source" button of an analog oscilloscope mean? Where should it be adjusted during normal use?
Synchronization trigger source, divided into + trigger and-trigger, internal synchronization, external synchronization. Triggering means that the oscilloscope starts to display the waveform.
For example, if you select CH1 as the trigger source and the rising edge as the trigger type, when CH1 has a rising edge and the amplitude reaches the trigger level, the oscilloscope will start scanning and display the waveform. The trigger point you see is on this rising edge.