[PART 02] Diploma in electronics and telecommunication engineering (ETC) interview question (Upcoming) 2023

2. Circuit Board Troubleshooting Techniques

A)      Confirm the real problem in the circuit or the problem due to the error in the circuit 

B)      consider a visual inspection first in the circuit

C)      Select the troubleshooting tools

D)      power the circuit

E)      check the power supply block or points

F)       check the individual components

G)     check the main controller

H)     check the loads on each component by the metered power supply

3)      What is the soldering bit temperature?

Soldering temperature range of 300 to 400 °C

4)      What is a DC chopper?

A chopper is a device that converts fixed DC input to a variable DC output voltage directly. Essentially, a chopper is an electronic switch that is used to interrupt one signal under the control of another.

chopper symbol

chopper circuit diagram

What is the principle of a DC chopper? 

DC chopper works on DC voltage. They work as step-up and step-down transformers on DC voltage. They can convert the steady constant DC voltage to a higher value or lower value based on their type. DC choppers are more efficient, fast, and optimized devices.   

 5) Current controlled devices?

In any (electronic) device controlling parameter is current it is called a current-controlled device. e.g., bipolar transistor-output current is a function of base current. In any (electronic) device controlling parameter is voltage it is called a voltage-controlled device.

 

6)      What is the ideal source voltage?

      Zero internal resistance.

 

7)      Which device has the ideal voltage source characteristics? 

      Zener Diode

9)      

amplifier symbol

amplifier circuit diagram

10)      

oscillator symbol

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12. What is a transistor?

A transistor is a semiconductor device used to amplify or switch electrical signals and power. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one pair of the transistor's terminals controls the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Some transistors are packaged individually, but many more are found embedded in integrated circuits.

There are three terminals for a transistor. They are:

• Base: This is used to activate the transistor.
• Collector: It is the positive lead of the transistor.
• Emitter: It is the negative lead of the transistor.

transistor symbol

• Types of Transistors?

• PNP transistor controlled by which current?

In a PNP transistor, the base current which enters into the collector is amplified.

•  Why do we use transistors?

A transistor can act as a switch or gate for electronic signals, opening and closing an electronic gate many times per second. It ensures the circuit is on if the current is flowing and switched off if it isn't. Transistors are used in complex switching circuits that comprise all modern telecommunications systems

13. 

• 14. Is AC voltage unidirectional or bidirectional?

AC is a bidirectional Current.

15. AC voltage can be converted by unidirectional by which component?

A rectifier is a device that converts alternating current (or voltage) into unidirectional current (or voltage). 

18. What is the Difference between Electronics & Electricals?

Electronics work on DC and with a voltage range of -48vDC to +48vDC. If the electronic device is plugged into a standard wall outlet, there will be a transformer inside which will convert the AC voltage you are supplying to the required DC voltage needed by the device. Examples: Computer, radio, T.V, etc...
Electric devices use line voltage (120vAC, 240vAC, etc...). Electric devices can also be designed to operate on DC sources but will be at DC voltages above 48v. Examples: are incandescent lights, heaters, fridges, stoves, etc.

Basis For Comparison	Electrical Device	Electronic Device
Definition	It is defined as a device that uses electrical energy for performing the work.	The device which controls the flow of electrons for performing the task is known as the electronic device.
Material Used	Metals like copper and aluminum are used for the conduction of current.	Semiconductor materials like silicon, germanium,  etc.
Operating Principle	Convert electrical energy into other forms of energy.	Uses electrical energy for performing the task.
Current	Alternating Current	Direct Current
Voltage	Works on high voltage.	Works on low voltage
Power consumption	More	Less
Manipulation	Do not manipulate the data	It manipulates the data.
Response Time	Fast	Slow
Required Space	More	Less
Safe	Less	More
Uses	For doing mechanical work.	For amplifying the weak signal or for coding and decoding the information.
Examples	Transformer, motor, generator etc.	Transistor, diode, microprocessor, flip-flop, amplifier, etc.

 

 

 

 19. What is Direct current (DC)?

Direct current (DC) is an electric current that is uni-directional, so the flow of charge is always in the same direction or one-directional. 

 An electrochemical cell is a prime example of DC power. Direct current may flow through a conductor such as a wire, but can also flow through semiconductors, insulators, or even

Through a vacuum as in electron or ion beams.

20. What is Alternating current (AC)?
An electric current that continually reverses direction.

The AC,  in which the electric charge reverses direction at regular intervals to produce alternate positive and negative values of the same magnitude.

The alternating current follows a sine waveform where the voltage increases steadily from zero, rising to the maximum positive peak voltage. It then reverses and drops down through zero into a negative direction until it reaches the negative peak value, which is equal to the positive in magnitude and only different in polarity. The voltage reverses again and climbs toward the zero point to complete one cycle. This process repeats at the rated frequency of either 50 HZ or 60 HZ (cycles per second).

 

21. What is Line voltage?

Line voltage is the voltage measured between any two lines in a three-phase circuit.

22. 

23. What are the transmitter, Receiver, and amplifier?

A transmitter is an electronic device used in telecommunications to produce radio waves in order to transmit or send data with the aid of an antenna. The transmitter is able to generate a radio frequency alternating current that is then applied to the antenna, which, in turn, radiates this as radio waves. Many modern devices that have communication capabilities have transmitters such as Wi-Fi, Bluetooth, NFC, and cellular.

The receiver is an electronic device that receives signals and radio waves that are transmitted by the transmitter. A decoder is installed in a receiver whose function is to decode and then send it to the amplifier. 

An amplifier is an electronic device that converts the signals sent by the receiver to a pair of speakers. The power and current of the signal are increased by an amplifier. The speakers are also known as amplifying devices.

25. What is Latch-Up? 

Latch-Up is a condition where a low impedance path is created between a supply pin and ground. This condition is caused by a trigger (current injection or overvoltage), but once activated, the low impedance path remains even after the trigger is no longer present.

28. What are the advantages of resistors?

• Resistors are very small in size.
• It is very easy to carry resistors from one place to another place.
• Resistors are very cheap.

32. 

34. 

36. Explain the radio environment in the building.

Ans: Building penetration: Building penetration depends on the material used for construction and the architecture used. This varies from building to building and is based on building construction.

Building Height Effect: The signal strength is always higher at the top floor and generally floor gain height is about 2.7 dB/floor which is not dependent on building construction.

Building Floor Reception: The signal isolation between floors in a multi-floor building is on average about 20dB. Within a floor of 150 * 150 feet, the propagation loss due to interior walls, depending on the wall materials is about 20 dB between the strong and the weak areas.

37. What is a conductor?

In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is generated by the flow of negatively charged electrons, positively charged holes, and positive or negative ions in some cases. 

44. What are the parts of a Network Management System (NMS)?

Ans: NMC is a set of hardware and/or software that allow a professional to supervise the individual components of a network within a large network management framework.

 Following are the parts of the network management system:

• OMC: Operation and maintenance center – Computerized monitoring center.
• NMC: Network Management Center – Centralized control of a network is done here.
• OSS: Operation and support system – Used for supporting activities performed in an OMC and/or NMC.
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• 45. How many satellites are required to cover the earth?

Ans: 3 satellites are required to cover the entire earth, which is placed at 120 degrees to each other.

47. What is handover and what are its types?

Ans: Handover in mobile communication refers to the process of transferring a call from one network cell to another without breaking the call. There are two types of handover which are as follows:

1. Hard Handoff: hard handoff is the process in which the cell connection is disconnected from the previous cell before it is made with the new one.
2. Soft Handoff: It is the process in which a new connection is established first before disconnecting the old one. It is thus more efficient and smart.

48. 

2. What is CDMA, TDMA, FDMA?

Ans: FDMA is an abbreviation for "Frequency Division Multiple Access". It is a form of channelization protocol. In this system, the bandwidth is separated into different frequency bands. Each station is assigned a band to transmit data, and that band is always reserved for that station.

TDMA is an abbreviation for "Time Division Multiple Access". It is a channelization system that divides channel bandwidth into many stations simultaneously. Each station is assigned a time slot and may only transmit data during the same time slot. Each station should be aware of the beginning and location of its time slot. Synchronization between stations is needed for TDMA. It is a form of data link layer access mechanism. The data link layer instructs each station to utilize the assigned time slot.

CDMA is an abbreviation for "Code Division Multiple Access". It is a combination of FDMA and TDMA in which resources are allocated based on frequency and time. FDMA divides the frequency band across several users for the duration of the session, whereas TDMA permits each user to utilize the full frequency band for a defined session. On the other hand, the CDMA system takes advantage of both systems by allowing several users to simultaneously utilize the same frequency band defined by a unique code.

54. 

55. Explain the concept of frequency reuse.

Frequency reuse is the process by which frequencies are allocated to new users. A cellular region, which is isolated to a certain geographic area, is allotted a certain number of frequencies. Within this region, cellular frequencies can be reused under certain circumstances. This has many benefits. The chief benefit is that system capacity can be increased without increasing the bandwidth of frequencies.