In this article we will discuss about the CRO working and application. we will also learn about the main construction of CRO.
CRO Working And Application.
The modern cathode ray oscilloscope provides a powerful tool for solving problems in electrical measurements. Some important applications of CRO are.
Application of CRO:
For measure waveform.
For measure voltage and current.
For measure frequency and phase angle.
For measure power , resistance Etc. these are provide help to know about cro working and application.
1. Examination of wave forms 2. Voltage measurement
3. Frequency measurement
1. Examination of waveform:
One of the important use of CRO is to observe the wave shapes of voltages in various types of electronic circuit circuits. For this purpose the single under study is applied to vertical input (vertical deflection plates) terminals of the oscilloscope. The sweep circuit is set to internal so that saw tooth wave is applied to the horizontal input that is horizontal deflection plates. Then various controls are adjusted to obtain sharp and well defined signal wave form on the screen.these are main application of CRO.
2. Voltage measurement
As discussed before, if the signal is applied to the vertical deflection plates only, a vertical line appears s on the screen. The height of the line is proportional to peak to peak voltage of the applied signal. The following procedure is adopted for measuring voltages type application of cro. By this application of cro these can do…
1. Shut off the internal horizontal sweep generator.
2. Attach a transparent plastic screen to the face of oscilloscope. Mark off the screen with vertical and horizontal lines in the form of graph.
3. Now, calibrate the oscilloscope against a known voltage. Apply the known voltage; say 10V, to the vertical input terminals of the oscilloscope. Since the sweep circuit is shut off, you will get a vertical line. Adjust the vertical gain till a good deflection is obtained. Let the deflection sensitivity be V volts /mm.
4. Keeping the vertical gain unchanged and apply the unknown voltage to be measured to the vertical input terminals of CRO.
5. Measure the length of the vertical the obtained
Let it be l mm.
The, unknown voltage = L x V volts.
3. Frequency measurement
The unknown frequency can be accurately determined with the help of a CRO. The steps of the procedure are as under. which are basic application of CRO.
1. A known frequency is applied to horizontal input and unknown frequency to the vertical input.
2. The various controls are adjusted
3. A pattern with loops cut by the horizontal line gives the frequency on the vertical plates and the number of loops curt by the vertical lien gives the frequency on the horizontal plates.
Working of CRO ( Cathode ray oscilloscope).
The oscilloscope is an electronic measuring device which provides a visual presentation of any wave form applied to the input terminals.
Cathode Ray tube (CRT) like a television tube provides the visual display of the signal applied as a waveform on the front screen. It is also known as cathode Tay oscilloscope (CRO).
What is CRO ?.
CRO full form is cathode ray oscilloscope. It is use to measure electrical parameters in time and amplitude form. it is used to obtain waveform when the different input signals are given. In the early days, it is called as an Oscilloscope. The oscilloscope observes the changes in the electrical signals over time, thus the voltage and time describe a shape and it is continuously graphed beside a scale. By seeing the waveform, we can analyze some properties like amplitude, frequency, rise time, distortion, time interval and etc.
Block Diagram of CRO (CRO working and application)
For knowing about CRO working and application we required to also know about the block diagram of CRO.
The Block diagram of CRO is shown below. It consists of various elements which must be known to us to understand the proper functioning of CRO.
It has mainly 5 part in it’s construction . By these points we can understand about working of CRO:
Cathode ray tube
Cathode ray tube : it is the main part of CRO which is known as heart of CRO. It is further divide into four part
Electron gun assembly: electron gun assembly is source of electrons.from where electron is generated and then by acceleration a direction is given. Electron is generated by cathode. On the edge of cathode, barium and strontium oxide layer is available. When it is heated electrons is generated. These electrons are passed from a control grid which give a required direction. Acceleration of electron is done by the help of anodes. These anodes are working on 1.5 kV supply. By focusing anodes electrons is focus towards screen. This is working on 500 volts.
Deflection plates: electrons coming from electron gun is passed through horizontal and vertical deflection plates. Vertical plates give direction in vertical (Y-axis) and horizontal plates give direction in horizontal (X-axis).
Florescent screen: a flat screen is in the front of CRO. Its normal size is 100mm×100mm. Screen is made of glass. It has a layer of phosphor . When electron hit the phosphor heat and light is generated, by this waveform is generated.
Glass envelope: complete CRT is packed into a close envelope. This envelope is stop disturbance of measurement. By which electron can flow smoothly.
Power supply: use of power supply is to powering up different different sections of CRO. For this a power transformer is use . This power transformer has many tapping of various voltage range in its secondary side. By using rectifier DC power is generated and use where required.
Amplifier: deflection system of CRO require a high voltage DC supply. For this amplifier is used.
Sweep generator: on screen of CRO, electron beam comes a very high speed. So that it is impossible to see by eyes. So a sweep generator is use to see. Sweep generator control the speed of electron beam. So that waveform can be measured.
Triggering circuit: work of triggering circuit is to switching of power supply and amplifier. By help of this require output get.
The input signal should be attenuated to a suitable magnitude before
it is applied to the amplifier. The attenuators are employed at the input of both vertical and horizontal amplifiers.
The amplifiers of an oscilloscope consist of a vertical amplifier and a horizontal amplifier. The vertical amplifiers amplify the vertical input signal before it is applied to the Y-plates. The horizontal amplifier amplifies the signal, before it is connected to the X-plates.
3. Saw-tooth Generator
For better know about CRO working and application we required to know about Saw-tooth generator.
The measuring signal of any shape is connected to the Y-input (plates) and then it appears on the screen. The signal on X-plates should be such that the image on the screen is similar to that on the Y-plates. Hence, a saw tooth signal is required to be connected to the x-plates which make the image on the screen like the signal connected at the vertical plate.
The saw-tooth signal is called the time base signal, and is produced by the saw-tooth generator. The shape of the saw-tooth signal is shown in figure. The time base signal consists of trace, retrace and hood-off period.
4. Gate Amplifier or Z-amplifier
It is desirable that the image seen on the screen of the CRT must be continuous. The electron beam is desired to appear only in the trace period of the time base signal. The retrace period of the electron beam must not be visible on the screen. Therefore, the gate amplifier is required to control the electron beam in order that it’s appears only in the trace period. It is very important for CRO working and application.
5. Trigger (Gate Amplifier Output)
As mentioned earlier, the measuring signal waveform is connected to Y-input, which appears on the screen.
In order to make the waveform stationary on the screen, it is required that the starting point of the time base signal has to be fixed related to the signal connected to the Y-input. This is known as synchronization.
There are three forms of triggering in an oscilloscope. For better know about CRO working and application we need to know about this.
1. Internal triggering
The signal which is supplied to the trigger is the internal signal of the CRO produced by using the signal form the vertical input signal.
2. External triggering
The signal which is supplied to the trigger is the external signal, produced by using the signal from the external synchronous.
3. Line Triggering
The signal which is supplied to the trigger is the signal from the power supply of CRO (not shown).
Switches are provided to select the form of triggers as required. In a CRO, suitable timing can be selected that causes the image on the screen to be stationary. these are provide help to understand about CRO working and application.
Application of CRO
1. Measurement of current
2. Measurement of voltage
3. Measurement of frequency
4. Measurement of inductance
5. Measurement of admittance
6. Measurement of power factor
7. Measurement of resistance.
Hence it is the CRO working and application. If you will find any incorrect above please comment below in comment box.