What Is The Use Of CRO (Cathode Ray Oscilloscope) ?

Cro cathode-ray oscilloscope is the device that is used to measure different parameters like voltage, current, frequency, phase angle, etc.

It was invented by German scientist Ferdinand Braun in 1897. Since a normal multimeter can't display some parameters like frequency, phase angle, etc. It only displays the end results that too in digital form but other things like the study of the waveform, analysis of various parameters cannot be done. Therefore it is used mostly in industries, college labs, etc.

The following is the Block Diagram of  Cathode Ray Oscilloscope:-

If you are not that much aware of what CRO is and how it works this article will explain to you very clearly. Let's assume that we are connecting the cro to the function generator.

At first, the output of the function generator is fetched to the attenuator.

Vertical Attenuator:-They are used to lower voltage coming from a function generator, dissipate power, and to improve impedance matching. In short, they are used to protect the measuring device from signal levels that might damage it.

Vertical Amplifier:-The main task of the amplifier is to amplify the weak signal so that it can produce measuring deflection on the screen. Thus the sensitivity and bandwidth of the cro are decided by the vertical amplifier.

Delay Line:-From the above block diagram it is clear that the signal will reach the vertical deflection plates first, before reaching to horizontal plates. Since the signal has to travel through different blocks before reaching to horizontal plates. So there arises a delay that causes distortion of a signal on the screen. So to overcome this distortion a delay line block is added.

Trigger Circuit:-This circuit generates trigger pulses that keep synchronization between input and horizontal deflection circuit.

Time Base Generator:-It generates the Sawtooth waveform and is applied in between the horizontal deflection plate.    

As the sawtooth wave varies linearly with time the movement of the spot on the screen takes place at a constant velocity.

Horizontal Amplifier:-The sawtooth waveform has weak strength that cannot be useful therefore this block is added to increase the strength of the sawtooth signal.

Crt Screen:-The output of the signal is displayed on the CRT screen by analyzing the output waveform, various parameters like voltage, frequency, etc can be calculated.

Besides all these blocks there are some other components like horizontal and vertical plates which are used to deflect the electrons horizontally and vertically respectively. Focus and intensity are controlled by Electron gun assembly.

Let's see how it is useful, let's understand it practically:-

@  I'm taking an example that I have a circuit lets say it is covered with some plastic body as shown in the figure given below:-

@  If  I'm applying some input signal through function generator I'm getting the output signal as shown below:-

@  Here is the video about the above discussion:
VIDEO:-

@  Thus by analyzing and studying the properties of the output signal I can conclude that the above circuit is a negative clipper circuit.

So from this example, you can conclude that by using a multimeter you can just calculate the value of the signal but by using cro you can analyze the behavior of the signal that means by using a cro you get a proper idea of how a circuit works.

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