The function of a trigger level knob on a CRO is:

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ALP CBT 2 Electrician Previous Paper: Held on 22 Jan 2019 Shift 2

To change the sweep speeds of time base
To change the length of time base
To change the intensity of the trace
To change the level of the input signal required to get stable display on the scope of the selected channel

Answer 1

Trigger (Gate amplifier output):

In CRO, the measuring signal-wave form is connected to Y-input, which appears on the screen.
In order to make the waveform stationary on the screen, it is required that the starting point of the time base signal has to be fixed related to the signal connected to the Y-input and this is known as synchronization.
The functional stage which performs synchronization is the trigger.
The trigger will produce a pulse or impulse for triggering the time base. Every time the time-base is triggered, one saw-tooth waveform is produced.

Trigger level:

It selects the mode of triggering.
In the AUTO position, the time-base line is displayed in the absence of the input signal.
When the input signal is present, the display is automatically triggered.

Intensity:

It controls the trace intensity from zero to maximum.
It controls the sharpness of the trace.
A slight readjustment of this control may be necessary after changing the intensity of the trace.

X-Magnification: It expands the length of the time-based from 1 to 5 times continuously, and makes the maximum time-base to 40ns/cm.