The diagram shows that when the delay line is not used, the initial part of the signal is lost and only part of the signal is displayed. To counteract this disadvantage the signal is not applied directly to the vertical plates but is passed through a delay line circuit, as shown in Fig. 7.13. This gives time for the sweep to start at the horizontal plates before the signal has reached the vertical plates. The trigger pulse is Picked off at a tune t0 after the signal has passed through the main amplifier. The sweep generator delivers the sweep ti; the horizontal amplifier and the sweep starts at the HDP at time t0 + 80 ns. Hence the sweep starts well in time, since the signal arrives at the VDP at time t0 + 200 ns.
Sync Selector for Continuous Sweep CRO
The sync selector is a 3-position switch, Int-Ext-Line. Therefore horizontal sweep can be synchronized with the signals coming from any of the three sources, as shown in Fig. 7.15.