Precautions while using Cathode Ray Oscilloscope
The cathode-ray oscilloscope (CRO) is a common laboratory instrument that provides accurate time.
21. Features and controls
Most function generators allow the user to choose the shape of the output from a small
number of options.Square wave The signal goes directly from high to low voltage.Sine wave The signal curves like a sinusoid from high to low voltage.Triangle wave The signal goes from high to low voltage at a fixed rate.
22. Phase measurement using lissajous patterns
To Measure the phase difference of two sine waves their frequencies must be equal.
1. Connect a 1Volt peak peak, 1KHz sine wave signal from the function generator to the horizontal input of the CRO.
2. Connect the output of phase shift network to the vertical input as shown in figure.
3. Adjust the vertical and horizontal gains properly for good display.
4. Observe Lissajous Patterns for different combinations of R and C values.
1. Connect a 1Volt peak peak, 1KHz sine wave signal from the function generator to the horizontal input of the CRO.
2. Connect the output of phase shift network to the vertical input as shown in figure.
3. Adjust the vertical and horizontal gains properly for good display.
4. Observe Lissajous Patterns for different combinations of R and C values.
23. Precautions
1. While doing the experiment do not exceed the ratings of the diode. This may lead to damage the diode.
2. Connect voltmeter and Ammeter in correct polarities as shown in the circuit diagram.
3. Do not switch ON the power supply unless you have checked the circuit connections as per the circuit diagram
2. Connect voltmeter and Ammeter in correct polarities as shown in the circuit diagram.
3. Do not switch ON the power supply unless you have checked the circuit connections as per the circuit diagram
24. How do you use an oscilloscope
Plug it in. Thats not facetious.Turn it on. There is a push button at the lower right edge of the screen. It says Line and indicates a 0 and a 1 setting. Depress that button.Apply a signal to the input terminals.Your oscilloscope may have provision for more than one signal input. Choose Channel 1 if that is the case.
25. Measuring a simple signal
Heres the connections for a simple signal measurement. The oscilloscope is being used to display the voltage output from a signal generator. You should do that also.
26. Some simple oscilloscope experiments
Being able to use an oscilloscope is an important skill for anyone who takes electrical measurements. In this section well present a few things you can do with oscillscopes to get better acquainted with them.The first thing to do is to become acquainted with the oscilloscope you have and to learn its capabilities and limitations. Here are some things to do.
27. Familiarisation with the main oscilloscope controls
There are a number of different models of oscilloscope in the first year laboratory. All
work on the same principal, but there are differences in the labelling of the controls
and exact way different modes of operation are selected. You will therefore find
alternatives at a number of points in the instructions below, and must determine which
is appropriate for the equipment you are using.
28. Single channel operation
1. Set the coupling of channel 1 input to DC and connect the signal generator to this
input. Note that the outer connectors of the coaxial sockets are connected to
earth. This means that if one of the signal generators terminals is also grounded,
the two grounded contacts must be the ones which are connected together. .
2. Set the generator to produce a sine wave of frequency 1 kHz and amplitude 1 V. Some signal generators specify the peak to peak amplitude or alternatively the r.m.s voltage. In these cases use 2 V p p or 1.41 V respectively .
3. If the signal generator has the option of adding a DC offset to the signal set this to 0V so that the signal is purely AC.
4. Reset the oscilloscope time base to 1 ms per division and set the channel gain to 0.5 V per division.
2. Set the generator to produce a sine wave of frequency 1 kHz and amplitude 1 V. Some signal generators specify the peak to peak amplitude or alternatively the r.m.s voltage. In these cases use 2 V p p or 1.41 V respectively .
3. If the signal generator has the option of adding a DC offset to the signal set this to 0V so that the signal is purely AC.
4. Reset the oscilloscope time base to 1 ms per division and set the channel gain to 0.5 V per division.
29. Two channel operation
1. Connect the signal generator 1 kHz, 1 V to the input and ground of the driver
box provided.
2. Connect output one of the box to channel 1 of the oscilloscope and output 2 to channel 2. It is essential that the two earthed sides are connected to each other and to the earthed connection of the generator, if one exists . Failure to observe this rule will result in part of the circuit under investigation being shorted out.
3. Set the oscilloscope to display both channels 1 and 2 DUAL display mode. On some oscilloscopes this requires two buttons to be depressed simultaneously.
4. Set both channel couplings to AC, and adjust the gain and position of channel 2 in order to display both traces.
2. Connect output one of the box to channel 1 of the oscilloscope and output 2 to channel 2. It is essential that the two earthed sides are connected to each other and to the earthed connection of the generator, if one exists . Failure to observe this rule will result in part of the circuit under investigation being shorted out.
3. Set the oscilloscope to display both channels 1 and 2 DUAL display mode. On some oscilloscopes this requires two buttons to be depressed simultaneously.
4. Set both channel couplings to AC, and adjust the gain and position of channel 2 in order to display both traces.
30. Use of the ac dc function
A general waveform may contain both an AC and DC component the latter will
appear as an offset of the AC waveform away from 0 V .When set to DC the oscilloscope displays all of the waveform DC and AC but in the AC setting the DC component is filtered out and only the AC component is displayed. This may be useful for cases where the DC component is significantly larger than the AC component making a measurement of the latter otherwise difficult.
