21. X-Y mode in Dual trace oscilloscope means ____________
2 modes
Vertical and horizontal
x-axis and y-axis
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.
22. How many vertical inputs exist in a dual-trace oscilloscope?
8
6
4
2
Answer.2. 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 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 trace, signals A+ B, A-B, B—A or (A + as a single trace.
23. After pre-amplification the signals are fed into ______
An electronic switch
A signal generator
A rectifier
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 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.
24. In alternate mode the change over of an electronic switch takes place during the ________
Flyback Period
Time-off Period
Trigger Period
None of the above
Answer.1. Flyback Period
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.
25. The main limitation of the alternate mode method is
Signals not represented simultaneously
Only used for high-frequency signal
Both 1 and 2
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.
26. ______ method, there is switching from one vertical channel to another many time during a single sweep.
Alternate Method
Sweep Method
Chop Mode
None of the above
Answer.3. Chop Mode
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.
27. Front panel control of dual trace oscilloscope consist of
Control Group
Horizontal Group
Vertical Group
All of the above
Answer.4. All of the above
Explanation:
The front panel control of dual trace oscilloscope can be divided into four major groups
Control Group
Horizontal Group
Vertical Group
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.
1. A dual-beam oscilloscope has ________
2 beams
4 beams
6 beams
8 beams
Answer.1. 2 beams
Explanation:
The two beams could be produced by two independent electron gun assemblies, or by a single gun and a splitter plate to slice the beam in half. An oscilloscope using this type of dual-trace operation is known as a dual-beam oscilloscope.
The dual-beam CRO uses two complete separate electron beams. The dual-beam analog oscilloscope can display two signals simultaneously. A special dual-beam CRT generates and deflects two separate beams.
28. Two voltages can be studied simultaneously by making use of __________
Single-electron gun
Two electron guns
Four electron guns
d) Six electron guns
Answer.2. Two electron guns
Explanation:
The two beams could be produced by two independent electron gun assemblies, or by a single gun and a splitter plate to slice the beam in half. An oscilloscope using this type of dual-trace operation is known as a dual-beam oscilloscope.
The dual-beam CRO uses two complete separate electron beams. The dual-beam analog oscilloscope can display two signals simultaneously. A special dual-beam CRT generates and deflects two separate beams
29. A dual beam oscilloscope has __________
8 vertical deflection plates
6 vertical deflection plates
2 vertical deflection plates
d) 4 vertical deflection plates
Answer.2. 2 vertical deflection plates
Explanation:
In dual-beam oscilloscopes, there are two vertical input signals.
In a dual-beam oscilloscope, a specially designed C.R.T. is used which is capable of producing two completely distinct electron beams so that they can be deflected independently in the vertical plane.
In the split beam technique, the single electron gun is split into two distinct beams mechanically. While in other techniques, two separate electron guns are used which produce their own beam.
Thus in dual beam, C.R.T. two sets of vertical deflection plates are used, one set for each channel but only one set of horizontal deflection plates. The simplified block diagram of dual-beam C.R.O.
30. In a dual-beam oscilloscope, the sweep generator is triggered by
Oscillator
Flip-flop
Transformer
d) Channel A or B
Answer.4. Channel A or B
Explanation:
The dual-beam oscilloscope has two vertical deflection plates and two separate channels A and B for the two separate input signals.
Each channel consists of a preamplifier and an attenuator. A delay line, main vertical amplifier, and a set of vertical deflection plates together form a single channel.
There is a single set of horizontal plates and a single time base circuit.
The horizontal deflection system consists of a sweep generator that drives a single set of horizontal deflection plates in the C.R.T. and sweeps both the vertical signals across the C.R.T. screen at the same rate.
The sweep generator can be triggered internally by the channel A signal or channel B signal.
As regards triggering of the sweep generator it can be done internally from either of channel or by the externally applied trigger or it can be triggered from the line voltage.
