JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III INTRODUCTION TO INSTRUMENTATION Previous Question Paper (August - 2022 - R18)

A Cathode Ray Oscilloscope (CRO) is a versatile electronic instrument used to visualize and measure time-varying electrical signals. The block diagram consists of the following components:

• Cathode Ray Tube (CRT): The heart of the CRO, where an electron beam is generated, accelerated, and focused onto a fluorescent screen to produce a visible spot.
• Vertical Amplifier: Amplifies the weak input signal to a level sufficient to drive the vertical deflection plates.
• Delay Line: Introduces a slight delay in the vertical signal path so that the horizontal sweep starts before the signal reaches the vertical plates, ensuring the leading edge of the waveform is visible.
• Time Base Generator: Generates a sawtooth waveform that provides a linear horizontal sweep, moving the electron beam across the screen at a constant rate.
• Horizontal Amplifier: Amplifies the sawtooth signal from the time base generator to drive the horizontal deflection plates.
• Trigger Circuit: Synchronizes the horizontal sweep with the input signal to ensure a stable display on the screen.
• Power Supply: Provides the high-voltage DC required for the CRT and low-voltage DC for the amplifier circuits.

Strip Chart Recorder: This device records a single variable as a function of time. It uses a continuous roll of paper moving at a constant speed beneath a pen. The pen moves perpendicularly to the paper motion proportional to the input signal amplitude. It is primarily used for monitoring slow-varying industrial processes over long durations.

XY Recorder: This instrument records the relationship between two independent variables, X and Y, rather than time. It utilizes two separate servo-motor systems: one to move the pen carriage horizontally (X-axis) and another to move the pen vertically (Y-axis) relative to a stationary or moving chart. It is essential for plotting characteristics like V-I curves, stress-strain diagrams, or hysteresis loops where the direct correlation between two signals is required.