oscilloscope must be negative. (See fig 5)
Function of trigger source:
In order to display a stable waveform on screen, a signal which is relate with display signal in time should be provided
to trigger circuit, the trigger switch is just used to select the trigger signal.
CH1/CH2:
Internal trigger mode in most cases. The signal which is sent to vertical input , separate one part to trigger
circuit before pre-amplify. As the trigger signal is just the signal under tested, a stable waveform will display on screen.
In DUAL or ADD mode, trigger signal is selected by trigger source switch.
LINE
: Use frequency of AC supply as trigger signal. This method is very available to test the signal relate with power
frequency. Such as AC noise of acoustic equipment, thyristor circuit etc.
EXT
: Drive scan trigger circuit by external signal. Since the external signal has certain time relate with the signal under
tested, the waveform can be display more independently.
Trigger level and polarity switch
It generates a sweep trigger signal when trigger signal through a preset valve level. The level can be changed by
selecting trigger level, valve level move to positive when adjust toward “+”. And valve level move to negative when
adjust toward “-”, and valve level set in average of signal when in centre. About positive signal, starting phase is
variable.
Note: if the trigger level is adjusted over-positive or over-negative, there is also no sweep signal
generates, because by now the trigger level has been exceed the amplitude of synchronized signal.
When the
polarity trigger switch set in “+”, rising edger triggered, and falling edge is triggered for “-”. (See fig 6)
6 Fig 6
Positive zone
Level
Trigger alternative switch
When vertical mode set in dual channel display, the switch used in alternative trigger and alternative display
(suitable for the mode of summarize with CH1, CH2).
In alternative mode, trigger signal alternates one time for every sweep period. This mode is avail for the test of
waveform amplitude and period, even the two waveform has no relative can be observed, but not suitable for measuring
of phase versus time. About this measurement, both channels must be trigger by the source synchronize signal.
In dual channel display, if “CHOP”:& “TRIG.ALT” depressed simultaneously, cannot synchronize display, due to
“CHOP” signal become trigger signal. Recommend to use “ALT” mode or directly select CH1 or CH2 as trigger signal
source.
7.
Sweep rate control
Adjust sweep rate knob, select the waveform number that you want to observe. If too many waveform display on
screen, adjust sweep time faster, if only one period waveform display on screen, can slow down the sweep time.
When the sweep rate is too fast, only a part of period signal can be observed. But there may be only one straight line
on screen for a square signal.
8. Sweep extension
Extreme high sweep rate is required when observe a part of a waveform. But if the part want to be observed is far
from starting point of sweep, the observed waveform may be out of screen. Now we need the sweep extension switch.
When the sweep extension switch is depressed, the display range can extend 10 times. Now the sweep extension switch
is (the value of “Sweep rate switch”) multiple by 1/10. e.g., 1uSec/div can be extended to 100nSec/div.
7
10
10 for extension
adjust position knob that you
