CRO Time Base Signal Shape
The time base signal in a Cathode Ray Oscilloscope (CRO) is crucial for generating the horizontal sweep across the screen. This signal dictates how the electron beam moves from left to right over time.
Why Sawtooth Wave is Ideal
A sawtooth wave is the standard choice for the CRO's time base signal due to its specific characteristics:
- Linear Sweep: The gradually increasing voltage portion of the sawtooth wave causes the electron beam to move horizontally across the screen at a constant, uniform speed. This creates a linear time axis, essential for accurately measuring time intervals and observing signal shapes.
- Fast Retrace: The sharp, rapid drop in voltage at the end of the sawtooth cycle quickly resets the electron beam to the starting point on the left side of the screen. This minimizes the "flyback" or retrace time, allowing for continuous observation.
Other Waveforms Considered
While other waveforms can be generated, they are less suitable for the CRO's time base function:
- Sine Wave: The sweep speed varies non-linearly throughout the cycle, making time measurements difficult and distorting the display.
- Square Wave: It causes an instantaneous jump, not a continuous sweep, and is unsuitable for displaying waveforms over time.
- Triangle Wave: Although it has linear portions, the combination of increasing and decreasing linear ramps makes it less ideal than a pure sawtooth for a consistent sweep.
Conclusion on CRO Time Base
The unique ramp-up and sharp drop characteristics of the sawtooth wave make it the most effective signal for achieving a predictable and linear horizontal sweep required for oscilloscope operation.
Correct Answer: Option D (sawtooth wave)
Similar Questions
A CRO displays a sine waveform which spans 3 cycles in 6 horizontal divisions. If the time base switch is set to 1 ms/div, what is the frequency of this signal which is being measured?
CRO stands for:
- How is a Lissajous pattern created?
Aquadag coating is most commonly used in CROs to:
- What cannot be measured using a CRO device?
Important Questions from Cathode Ray Oscilloscope
Calculate the maximum velocity of the beam of electrons in a CRT having a cathode and anode voltage of 182 V. Assume that the electrons leave the cathode with zero velocity. (Charge of electron = 1.6 × 10-19 C and mass of electron = 9.1 × 10-31 kg)
Which of the following expression is the correct formulae for the deflection sensitivity ‘S’ of a CRT, if
D = deflection on the fluorescent screen
L = distance from the center of the deflection plates to the screen
Ld = effective length of the deflection plates
d = distances between the deflection plates
Ed = Potential between deflecting plates
Ea = accelerating voltageTrigger pulses in CRO are used -
- A Lissajous pattern obtained on a CRO screen is a straight line. The frequencies of the two signals are
Which element in CRO is used to collect secondary emission electrons?
