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some functions of O-scope

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PG1995

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Hi

Please have a look on this picture of the oscilloscope:
http://img8.imageshack.us/img8/5408/oscillo.jpg

It would be nice of you if you could explain some of these functions. I have seen many videos on O-scope but couldn't find the explanation anywhere.

1: At the top what do "TRIG LEVEL" and "COUPLING" mean?

2: What is the function of SOURCE switch?

3: What is the function of "VAR SWEEP"?

Regards
PG
 

doraemon

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Hello!

1. Trig level is the level at which you want the trigger to work. For instance, if you display a sine wave,
if you set the trigger level at 0, then the sine wave should be "centered" around the trigger point.
Try to input a sine wave and then play with the trigger level. If it's too high (more than the signal
max) or too low (less than the signal min) then your signal will not be synchronized.

2. Source is the source of the trigger, allowing to specify which signal you want to use to trigger.
It can be either of the channels or external trigger that you would input in "EXT TRIG" at the bottom
right.

3. VAR SWEEP. Usually the sweep time is determined by the rotary button "TIME / DIV". Now if you
want this time to be variable (that may be useful if you want to measure a duty cycle, for example),
then you can narrow or widen your signal so that 1 period fits within a specific number of divisions
(for instance 5 squares). Then you can easily measure the on and off times.
Basically var sweep is the same function as the "VAR" potentiometer at the center of your amplifier
controls, but it controls the speed of the trace.
CAREFUL: usually CAR SWEEP should always be tuned to its max (labeled CAL), otherwise all your
time measurements will be wrong.

Dora.
 
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Kral

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1 TRIG LEVEL: When viewing a signal, you normally want the displayed trace to begin at a specific point on the input waveform. The TRIG LEVEL (Trigger level) lets you determine (adjust) when the display trace begins with respet to the input signal. For example if you are observing a sine wave, you might want the trace to begin at the positive-going zero crossing, the negative going zero crossing, or somewhere in between. The TRIG LEVL control lets you adjust this.
.
2 The Coupling switch allows you to select AUTO (free running) where the displayed trace repeats at a rate determined by the Time/DIV control independently of the input signal. This setting is seldom used becauses it does not give a consistent display. You end up with a blur which is hard to interpret. The NORM position allows you to synchronize the display with the input signal as explained above. The EXT position behaves in a similar manner, expept that the display is now synchronized with a signal connected to the EXT TRIG input. If the EXT INPUT and the input signal are connected together, then the scope operates identically as described in the first paragraph above. The TV-V and TV-H are designed to synchronize the display with the vertical or horizontal synch pulses of a TV set.
.
The SOURCE switch lets you determine whether the display is synchronized with the signal on Channel 1, Channel 2, the Power (Mains) line, or the EXT TRIG input.
.
The VAR Sweep allows you to change the horizontal sweep rate to either the value set by the TIME/DIV, or a slower value determined by the position of the VAR SWEEP knob. WHen the VAR SWEEP Knob is in the "Cal" position, the sweep rate will be the rate selected by the TIME/DIV control. Otherwse it will be a lower rate as determined by the position of the VAR SWEEP knob.
 
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PG1995

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Thanks a lot, doraemon, Kral, for letting me know this. I'm sorry I have been little late in extending many thanks. Actually I was away. Much grateful.:smile:

Cheers
PG
 

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