Electronic System Design (ESD) Lab Viva Questions
1. What you know about signal sampling?
In signal processing, we can define the sampling process as the process of conversion of an analog signal to a discrete one. The example for signal sampling is the conversion of a sound signal.
The continuous time signal is the sound signal and the discrete time signal is its sample sequences.
2. What are the different modes of operations of a 555 timer. Draw the circuits of each mode?
For a 555 timer, there are mainly 3 types of operating modes, namely Monostable, Astable and Bistable. Each modes are different types of circuits having different outputs.
Monostable Mode
Astable Mode
Bistable (Schmitt Trigger) Modes.
3. What you know about Silicon Controlled Rectifiers (SCR)?
Silicon Controlled Rectifiers (SCR) is also known as Thyristors has many uses in electronics, particularly in power control applications. SCRs are the workhorse of high power electronics. SCRs are capable of switching to large power levels. SCRs can also be used in different circuits from light dimmers to power supply over voltage protection.
SCR consists of 4 types of substrates (P-N-P-N) and can be produced by merging a PNP and a NPN transistors. SCR has 3 junctions namely anode, cathode and gate.
4. Draw the symbol and the characteristics of an SCR?
SCR symbol
SCR Characteristics
5. What you understand about ZIGBEE?
For the unique needs of low cost, low-power wireless IoT networks, as an open global standard, a wireless technology is developed and is termed as Zigbee. Zigbee is a IEEE 802.15.4 based specification. This is a high level communication protocol used for creating personal area networks with small, low power digital radios. ZIGBEE can be operated in unlicensed bands like 2.4 GHz, 900 MHz and 868 MHz .
6. What you know about a printed circuit board (PCB)?
The main use of a PCB is for the electrical connection of the electronic components and the mechanical support of electronic devices. This can be achieved by using pads, conductive tracks and other features etched from copper sheets laminated to a non conductive substrate.
7. What is the use of a data modem in communication?
Modem is the short form of modulator-demodulator. We can define modem as a device, that is used for sending and receiving data from a computer to telephone or cable lines. Modems can transfer data secure, fast and correctly. In the computer, the data is stored digitally and in cables the data is stored in analog form. The application of modem is to convert data from digital to analog and vice versa. At the time of data transfer (sending)from computer, the modem converts digital data to analog form. When the data is being received by the computer, the modem converts the analog data to digital form.
An amplifier is an electronic device which increases the input signal's voltage, current, or power. The main applications of amplifiers are: in wireless communications and broadcasting, audio devices etc. Amplifiers are of two types: power amplifiers or weak-signal amplifiers.
In wireless receivers, weak-signal amplifiers are mainly used. They are also employed in acoustic pickups, compact disc players, and audio tape players. Weak signal amplifiers are designed for dealing with extremely limited input signals.
Wireless transmitters, broadcast transmitters, and hi-fi audio devices uses power amplifiers. The bipolar transistor (B JT) is the most commonly used device for power amplification.
Figure: Class A Power Amplifier
9. How can you define a voltage controller?
We can define a voltage controller as thyristor based devices, that is used for converting fixed alternating voltage to variable alternating voltage without a change in frequency. , Thyristors and TRIACs are line-commutated, since phase-controlled devices are AC Voltage controllers. The main drawback of ac voltage controllers is the introduction of objectionable harmonics, especially at reduced output voltage levels, in the supply current and load voltage waveforms.
The main applications of voltage controllers are: domestic and industrial heating, tap shift transformer, lighting control, single-phase and three-phase ac-drive speed control, induction motor start-up. For closed loop control systems, AC voltage controls are adaptable.
10. Define a microcontroller system and a microprocessor?
Microcontroller:
A microcontroller is a device present in a single integrated circuit which is dedicated to perform one task and execute one particular programme.
It includes memory, programmable peripherals for input/output, as well as a processor. Microcontrollers are mainly designed for embedded applications and are commonly used in electronic devices such as cellphones, cameras, microwave ovens, washing machines, etc that are automatically operated.
Microprocessor:
An integrated circuit (IC) that integrates key functions of the central processing unit (CPU) of a computer is a microprocessor. It is a programmable, clock-driven, register-based multipurpose silicon chip that accepts binary data as input and provides output after processing it as per the memory-stored instructions.
11. Compare AM and FM?
Amplitude modulation (AM) is a type of modulation where, depending on the information signal, the amplitude of a carrier signal varies. Higher carrier frequencies are used for AM radio transmission signals, allowing them to travel long distances. AM signals can often be capable of bouncing off the ionosphere. The distance that the AM travels is much greater than that of the FM.
In Frequency Modulation (FM), the frequency of the carrier wave is modified according to the signal that carries the information. The radio signals have a high bandwidth compared to AM radio signals, which helps to have a much better quality of sound. Frequency modulation also allows stereo signals to transmit.
12. Give the differences of AC and DC voltages?
The electric charge (current) only flows in one direction in the case of direct current (DC). In the other hand, the electric charge in the alternating current (AC) changes its directions periodically. Since the current changes direction, the voltage also periodically reverses in AC circuits.