Como Usar Un Osiloscopio

USING AN OSCILLOSCOPE


What does an oscilloscope do?




An oscilloscope is easily the most useful instrument available for testing circuits because it allows you to see the signals at different points in the circuit. The best way of investigating an electronic system is to monitor signals at the input and output of each system block, checking that each block is operating as expected andis correctly linked to the next. With a little practice, you will be able to find and correct faults quickly and accurately.
An oscilloscope is an impressive piece of kit:

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The diagram shows the front of an oscilloscope. Your oscilloscope may look different but will have similar controls.
The function of an oscilloscope is extremely simple: it draws a V/t graph, a graph of voltageagainst time, voltage on the vertical or Y-axis, and time on the horizontal or X-axis.
As you can see, the screen of this oscilloscope has 8 squares or divisions on the vertical axis, and 10 squares or divsions on the horizontal axis. Usually, these squares are 1cm in each direction:
Many of the controls of the oscilloscope allow you to change the vertical or horizontal scales of the V/t graph, sothat you can display a clear picture of the signal you want to investigate. 'Dual trace' oscilloscopes display two V/t graphs at the same time, so that simultaneous signals from different parts of an electronic system can be compared.


Setting up




1. Someone else may have been twiddling knobs and pressing buttons before you. Before you switch the oscilloscope on, check that all thecontrols are in their 'normal' positions. In our example’s oscilloscope, this means that:

• all push button switches are in the OUT position.
• all slide switches are in the UP position.
• all rotating controls are CENTRED.
• the central TIME/DIV and VOLTS/DIV and the HOLD OFF controls are in the calibrated, or CAL position.

Check through all the controls and put them inthese positions:

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2. Set both VOLTS/DIV controls to 1 V/DIV and the TIME/DIV control to 2 s/DIV, its slowest setting:

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VOLTS/DIV TIME/DIV

3. Switch ON, red button, top centre:

The green LED illuminates and, after a few moments, you should see a small bright spot, or trace, moving fairly slowly across the screen.

4. Find the Y-POS 1 control:What happens when you twiddle this?
The Y-POS 1 allows you to move the spot up and down the screen. For the present, adjust the trace so that it runs horizontally across the centre of the screen.

5. Now investigate the INTENSITY and FOCUS controls:

When these are correctly set, the spot will be reasonably bright but not glaring, and as sharply focused as possible.
Adjusting the INTENSITYcontrol changes the brightness of the oscilloscope display. The FOCUS should be set to produce a bright clear trace.
The TR control is screwdriver adjusted. It is only needed if the spot moves at an angle rather than horizontally across the screen with no signal connected.

6. The TIME/DIV control determines the horizontal scale of the graph which appears on the oscilloscope screen.

With 10squares across the screen and the spot moving at 0,2s/DIV, how long does it take for the spot to cross the screen? The answer is 0,2 x 10 = 2 seconds.
Now rotate the TIME/DIV control clockwise:
With the spot moving at 0,1s/DIV, it will take 1 second to cross the screen.
Continue to rotate TIME/DIV clockwise. With each new setting, the spot moves faster. At around 10ms/DIV, the spot is no longerseparately visible. Instead, there is a bright line across the screen. This happens because the screen remains bright for a short time after the spot has passed, an effect which is known as the persistence of the screen. It is useful to think of the spot as still there, just moving too fast to be seen.
Keep rotating TIME/DIV. At faster settings, the line becomes fainter because the spot is...