Electrical Engineering ⇒ Topic : Cathode Ray Oscilloscope (CRO)

Cathode Ray Oscilloscope (CRO):-

     The CRO is an electronic device which gives a visual indication of the waveform of the signal being measured, i.e. voltage, current, frequency etc. It is a very versatile instrument and is very widely used in learning, in research, in industry and as a part of many display devices. It is used to study the shape of the signal as well its amplitude, phase shift, etc

CATHODE RAY OSCILLOSCOPE (CRO)

Indicating instruments enable us to measure the unknown quantity. With the help of cathode ray oscilloscope (CRO) we can not only measure but also see the magnitude. The chief defect of the measuring instruments is their slow response. In a CRO, the measurable quantity can move with the speed of the electron which, for reasonable values of voltage, can be more than 0.1c (33 nanoseconds per metre). The oscilloscope has become such a versatile instrument that a number of refinements and improvements have been made over the years to suit various purposes of the analyst and experimenter.

Oscilloscope consists of the CRO tube, amplifiers, controls, and power supplies. It is a portable self-contained instrument. The heart of the oscilloscope is the cathode ray tube since it converts the signal to image. The image is traced and illuminated on its screen in the X-Y plane.On the Z-axis is the electron beam whose speed and intensity can be controlled and modulated. Capture, display, and analyze are the three functions of an oscilloscope. Oscilloscope obtained a big boost with the advent of computers as any stored data can be immediately displayed and analyzed.

The parts of an oscilloscope are: (i) Cathode ray tube (CRT) for display, (ii) Vertical amplifier including probe or transducer, (iii) Time base, (iv) Horizontal amplifier, (v) Trigger circuit, (vi) Gate amplifier (it turns on CRT for display and off without signal), (vii) Power supplies.

Figure (a) shows the block diagram of a CRO.

                                                             figure (a) Block diagram of CRO