# Dual Trace Oscilloscope MCQ || Dual Trace Oscilloscope Questions and Answers

1. The dual-slope oscilloscope is needed to _________

1. Compare more than two voltages
2. Measure the voltage
3. Measure the current
4. Measure the time

Answer.1. Compare more than two voltages

Explanation:

• The dual-trace oscilloscope has one cathode ray gun with an electronic switch, which switches two signals to a single vertical amplifier.
• Sometimes it is necessary to compare the two or more voltage waveforms to analyze the electronic circuits and systems. It can be done by using two or more oscilloscopes but it is difficult to trigger the sweep of each oscilloscope precisely at the same time. This problem is solved by the use of dual trace or multitrace oscilloscopes.
• In this method, the same electron beam is used to generate two traces that can be deflected from two independent vertical sources.

2. Which technique of a Dual Trace Oscilloscope maintains the phase between the signals?

1. Analog mode
2. Mixed mode
3. Chop mode
4. Alternate mode

Explanation:

• The dual-trace oscilloscope has one cathode ray gun with an electronic switch, which switches two signals to a single vertical amplifier.
• The dual-trace oscilloscope has one cathode ray gun with an electronic switch, which switches two signals to a single vertical amplifier.
• To display two waveforms, the single beam must somehow be shared between the two traces.
• Dual trace oscilloscopes almost invariably offer a front panel selectable choice of alternate and chopped modes as well as between traces.

3. What is the problem with using more than one oscilloscope?

1. Measuring the signal’s parameters
2. Triggering
3. Supply voltage
4. Errors in reading

Explanation:

• Sometimes it is necessary to compare the two or more voltage waveforms to analyze the electronic circuits and systems. It can be done by using two or more oscilloscopes but it is difficult to trigger the sweep of each oscilloscope precisely at the same time. This problem is solved by the use of dual trace or multitrace oscilloscopes.
• In this method, the same electron beam is used to generate two traces that can be deflected from two independent vertical sources.

4.  Electronic switch in Dual trace oscilloscope is controlled by _________

1. D flip-flop
2. SR flip-flop
3. T flip-flop
4. JK flip-flop

Explanation:

In a Dual trace Oscilloscope, there are two separate vertical input channels A and B. A separate preamplifier and attenuator stage exists for each channel. Hence amplitude of each input can be individually controlled. After the preamplifier stage, both the signals are fed to an electronic switch. The switch has the ability to pass one channel at a time via delay line to the vertical amplifier.

An electronic switch is controlled by using a toggle flip-flop. The switching takes place at the start of each new sweep. The switching rate of an electronic switch is synchronized to the sweep rate so that CRT spot traces channel A signal on one sweep and channel B signal on the next succeeding sweep.

Thus two-channel are alternately connected to the vertical amplifier. The change over of an electronic switch takes place during the flyback period of the sweep.

5. Independent traces can be obtained using ____________

1. 4 methods
2. 6 methods
3. 2 methods
4. 8 methods

Explanation:

1. The comparison of two or more voltages is very much necessary in the analysis and study of many electronic circuits and systems.
2. This is possible by using more than one oscilloscope but in such a case it is difficult to trigger the sweep of each oscilloscope precisely at the same time.
3. A common and less costly method to solve this problem is to use dual-trace or multitrace oscilloscopes.
4. In this method, the same electron beam is used to generate two traces that can be deflected from two independent vertical sources.
5. The two methods are used to generate two independent traces which are the alternate sweep method and other is chop method.

6.  X-Y mode in Dual trace oscilloscope means ____________

1. 2 modes
2. Vertical and horizontal
3. x-axis and y-axis
4. Ground and full-line supply

Answer.2. Vertical and horizontal

Explanation:

In a Dual trace Oscilloscope, there are two separate vertical input channels A and B. A separate preamplifier and attenuator stage exists for each channel. Hence amplitude of each input can be individually controlled. After the preamplifier stage, both the signals are fed to an electronic switch. The switch has the ability to pass one channel at a time via delay line to the vertical amplifier.

The X-Y mode means the oscilloscope operates from A as the vertical signal and channel B as the horizontal signal. Thus in this mode very accurate X-Y measurements can be done.

7. How many vertical inputs exist in a dual-trace oscilloscope?

1. 8
2. 6
3. 4
4. 2

Explanation:

In a Dual trace Oscilloscope, there are two separate vertical input channels A and B. A separate preamplifier and attenuator stage exists for each channel. Hence amplitude of each input can be individually controlled. After the preamplifier stage, both the signals are fed to an electronic switch. The switch has the ability to pass one channel at a time via a delay line to the vertical amplifier.

The X-Y mode means the oscilloscope operates from A as the vertical signal and channel B as the horizontal signal. Thus in this mode very accurate X-Y measurements can be done.

In a Dual Trace Oscilloscope, two vertical inputs exist. The two channels are known as A and B.  Depending on the selection of front panel controls several modes of operation can be selected such as channel A only, channel B only, channel A and B as separate traces, signals A+ B, A-B, B—A or (A + as a single trace.

8. After pre-amplification the signals are fed into ______

1. An electronic switch
2. A signal generator
3. A rectifier
4. A regulator

Answer.1. An electronic switch

Explanation:

In a Dual trace Oscilloscope, there are two separate vertical input channels A and B. A separate preamplifier and attenuator stage exists for each channel. Hence amplitude of each input can be individually controlled. After the preamplifier stage, both the signals are fed to an electronic switch. The switch has the ability to pass one channel at a time via a delay line to the vertical amplifier.

An electronic switch is controlled by using a toggle flip-flop. The switching takes place at the start of each new sweep. The switching rate of an electronic switch is synchronized to the sweep rate so that CRT spot traces channel A signal on one sweep and channel B signal on the next succeeding sweep.

9.  In alternate mode the change over of an electronic switch takes place during the ________

1. Flyback Period
2. Time-off Period
3. Trigger Period
4. None of the above

Explanation:

The change over of an electronic switch takes place during the flyback period of the sweep. During the flyback, the electron beam is invisible and the change over is also invisible i.e. without flicker. Thus the alternate mode displays one vertical channel for a full sweep and the next vertical channel for the next sweep.

10. The main limitation of the alternate mode method is

1. Signals not represented simultaneously
2. Only used for high-frequency signal
3. Both 1 and 2
4. None of the above

Answer.3. Both 1 and 2

Explanation:

The main limitation of the alternate mode method in dual trace CRO is that the display is not the actual representation of two events taking place simultaneously. The signals are displayed as if they were existing at two different times.

Similarly, the alternate mode cannot be used for displaying very low-frequency signals.

11. ______ method, there is switching from one vertical channel to another many times during a single sweep.

1. Alternate Method
2. Sweep Method
3. Chop Mode
4. None of the above

Explanation:

In Chop mode there is a switching from one vertical channel to other, many times during a single sweep. This switching from one vertical channel to other is at such a rapid rate that the display is created from small segments of the actual waveform.

The electronic switch is free running oscillator at a rate of 100 to 500 kHz independent of the sweep generator frequency. Thus the switch successively connects the small segments of the channel A and B waveforms to the main amplifier.

12. Front panel control of dual trace oscilloscope consist of

1. Control Group
2. Horizontal Group
3. Vertical Group
4. All of the above

Answer.4. All of the above

Explanation:

The front panel control of a dual trace oscilloscope can be divided into four major groups

1. Control Group
2. Horizontal Group
3. Vertical Group
4. Trigger Group

(a) Control Group: This group includes the following controls:

(i) Focus: This controls the size of the electron beam spot on the screen.

(ii) Trace rotation: Due to external fields or internal disturbance, if the trace is not horizontal then using the screwdriver adjustment beam can be made horizontal.

(iii) Calibration: It provides a standard signal to calibrate the vertical amplifier control. In most CROs, it is a square wave of 1 V peak to peak.

(iv) Intensity: It is generally the part of on/off control and brightness of the CRT that can be controlled using this control.

(v) Power on/off: The power to the device can be turned on or off using this control.

(b) Horizontal Group: This group includes the following control:

(i) Horizontal position: It moves the trace left and right on the screen.

(ii) Sweep mode: The sweep mode control selects the various modes such as automatic (AUTO), normal (NORM), and single sweep (SINGLE).

(iii) Sweep time: It is the main horizontal timing control. The time per division required to sweep the beam from left to right on the CRT screen can be determined using this control.

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