Operating Instructions—Type 324
change in signal level. Continue the counterclockwise move
ment of the TRIGGER control and note that triggering
occurs at progressively more positive points of the wave
form. See Fig. 2-7(B). Continue the rotation through the
control center position. The trace w ill disappear or become
unstable, then reappear, being triggered by the positive
change in signal level. See Fig. 2-7(C). Leave it in this posi
tion. Either AUTO or manual trigger selection may be used
in normal operation, as determined by the application and
the operator's preference. It is suggested that AUTO be
used in most applications, switching to manual when neces
sary to improve stability, increase the low-frequency trig
gering range, or to change the triggering point.
24.
Switch the Trig/Horiz Coupling lever to EXT TRIG
OR HORIZ-AC. Note that the trace disappears. A t the side
panel, connect the 2 volt peak-to-peak sine wave signal to
the EXT TRIG OR HORIZ INPUT connector. (Keep the
P6049 Probe connected to the 2 volt peak-to-peak sine
wave.) Note that a stabilized trace appears. Decrease the
generator frequency until the trace disappears and then
note the frequency. (The triggering circuit half-power point
occurs at approximately 16 Hz during AC-coupled opera
tion.)
25.
Switch the Trig/Horiz Coupling control to DC, and
the TIM E /D IV control to 2 mS. Note that the trace reap
pears. Decrease the signal generator frequency to 2 Hz.
Note that a stable trace remains. (Readjust the TRIGGER
Level if necessary.) When DC coupling is selected and the
TRIGGER control is not at AUTO, a trigger can be gener
ated whenever the EXT TRIG OR HORIZ INPUT voltage
passes through the DC value selected by the TRIGGER
Level control, even though the transistion is made very
slowly. If the signal has a DC bias, the trigger point w ill be
influenced by that bias.
a
+ Slope triggering
TRIGGER
.o _
TRIGGER
o
TRIGGER
o
26.
Switch the TRIGGER control to +AUTO. Note that
the trace becomes unstable. The trigger input becomes AC-
coupled whenever the TRIGGER control is at AUTO, re
gardless of the setting of the Trig/Horiz Coupling lever. The
2 Hz signal frequency is too low to cause AC-coupled trig
gering to occur. Increase the generator frequency to 60 Hz
and note that the display becomes stable, indicating that
the sweep is again being triggered by the input signal.
27.
Disconnect the signal from the EXT TRIG OR
HORIZ INPUT connector. Switch the Trigger Coupling
lever to I NT TRIG A CLF REJ. Note that the trace is again
unstable. Change the generator frequency to 10 kHz and
note that the trace stabilizes. A CLF REJ greatly reduces
circuit sensitivity to internal trigger signals of approxi
mately 10 kHz and lower, to prevent low-frequency signals
from randomly triggering the sweep while high frequency
signals are being observed.
XY Operation
N O TE
Whenever the Type 324 Oscilloscope is operated in
E X T H O R IZ m ode, the C R T is unblanked and no
in te rn a l sweep is available. I f no in p u t signal is
present a t the vertical o r h o riz o n ta l in p u t connector,
a b rig h t sta tio n a ry d o t w ill appear. I t is recom m ended
th a t the brightness be reduced to provide an in te n s ity
which is consistent w ith good viewing. Decreasing
beam in te n s ity w ill also increase battery-operating
time.
28.
Reconnect the signal generator output to the EXT
TRIG OR HORIZ INPUT jack. Switch the T IM E /D IV con
trol to EXT HORIZ and the Trig/Horiz Coupling lever to
Fig. 2-7. Selection of triggering point.
EXT TRIG OR HORIZ-AC. The straight diagonal line rising
®
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