Page 56 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Fig 3

Gate amplifier or Z-amplifier: It is desirable that the image seen on the screen of the CRT must be continuous,
that is, the electron beam is desired to appear only in the trace period of the time-base signal. The retrace period
of the electron beam must not be visible on the screen. Therefore, the gate amplifier is required to control the
electron beam in order that it appears only in the trace period.

The signal from the gate amplifier is a square wave and is related to the time-base signal. This is illustrated in
Fig 5.
Trigger (Gate amplifier output) : As mentioned earlier, the measuring signal-wave form is connected to Y-input,
which appears on the screen. In order to make the wave-form 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. This is known
s ‘synchronization’. The functional stage which performs synchronization is the trigger.

Fig 4 Fig 5

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CITS : Power - Electrician & Wireman - Lesson 60-69