Skip to main content

Design of Electronic Devices & Circuits - short answer questions from AMIE exams (Winter 2019)

Choose the correct answer for the following (10 x 2)

1. An example of a military-grade op-amp with a higher slew rate is
(a) 741
(b) 741 C
(c) 741 A
(d) 741 S

2. A non-inverting amplifier with a gain of 100 is nulled at 25°C. Determine the output voltage if the temperature rises to 40°C for an offset voltage drift of 0.15 MV/°C.
(a) 600 MV
(b) 450 MV
(c) 225 MV
(d) 60 MV

3. An example of a negative regulator is
(a) LM117
(b) LM137
(c) LM217
(d) LM317

4. The operational transconductance amplifier outputs a current proportional to its
(a) Input voltage
(b) Input resistance
(c) Input capacitance
(d) Input conductance

5. A second-order low-pass filter has a roll-off rate of
(a) - 40 dB/octave
(b) - 40 dB/decade
(c) - 20 dB/octave
(d) - 20 dB/decade

6. A quadrature oscillator generates both 
(a) Cosine wave and rectangular wave 
(b) Cosine wave and triangular wave 
(c) Cosine wave and sawtooth wave 
(d) Cosine wave and sine wave

7. A pulse position modulator can be built using a 555
(a) Monostable multivibrator
(b) One shot multivibrator
(c) Astable multivibrator
(d) Schmitt trigger

8. A PLL that is very useful as an FSK. demodulator is
(a) 565 PLL
(b) 564 PLL
(c) 562 PLL
(d) 561 PLL

9. A 64-input multiplexer can be built using
(a) Thirty-two two input MUXs
(b) Nine eight input MUXs
(c) Eight eight input MUXs
(d) Sixteen four input MUXs

10. Consider a 1024-bit ROM. How many address bits does it require?
(a) 16
(b) 12
(c) 10
(d) 8

Answers

1. (d) Op-amp ICs varying in the version of 741 are highly approved or sanctioned for military-grade since the temperature range lies within -55° to 125°C. So, as the temperature level range display variations, the op-amp IC741 are further sub-categorized under 741C, 741A & 741E & so on. Besides these, 741S & 741SC are recommended for military and commercial aspects due to the high slew rate.

2. (c) Input offset voltage due to temperature rise = 0.15 mV/°C x (40°C -25°C) = 2.25 mV. Since this is an input change, the output voltage will change by
Vo = Vos x ACL = 2.25 mV x 100 = 225 mV
This could represent a very major shift in the output voltage.

3. (b) 

4. (d) The operational transconductance amplifier produces an output voltage proportional to an input current. 

5. (b) Second Order (or two-pole) Filters consist of two RC filter sections connected together to provide a -40dB/decade roll-off rate.


6. (d) 


7. (a)

8. (a) 

9. (b) To build 64-input MUX: 
1st stage = 64/8=8
2nd  stage = 8/8=1
The sum will give the total number of 8-input MUXs. needed 
n = 8 + 1 = 9

10. (c) The size of the ROM is 1024 × 8 = 210× 8 Here 10 indicates the address bus. Therefore, the address bus with a ROM of size 1024 × 8 bits is 10 bits.

---

The study material for AMIE/Junior Engineer exams is available at https://amiestudycircle.com

Comments

Popular posts from this blog

Mechanics of Fluids (Solved Numerical Problems)

Numerical The surface Tension of water in contact with air at 20°C is 0.0725 N/m. The pressure inside a droplet of water is to be 0.02 N/cm² greater than the outside pressure. Calculate the diameter of the droplet of water. (7 marks) (AMIE Summer 2023) Solution Surface tension, σ = 0.0725 N/m Pressure intensity, P = 0.02 N/m 2 P = 4σ/d Hence, the Diameter of the dropd = 4 x 0.0725/200 = 1.45 mm Numerical Find the surface tension in a soap bubble of 40 mm diameter when the inside pressure is 2.5 N/m² above atmospheric pressure. (7 marks) (AMIE Summer 2023) Answer: 0.0125 N/m Numerical The pressure outside the droplet of water of diameter 0.04 mm is 10.32 N/cm² (atmospheric pressure). Calculate the pressure within the droplet if surface tension is given as 0.0725 N/m of water. (AMIE Summer 2023, 7 marks) Answer: 0.725 N/cm 2   Numerical An open lank contains water up to a depth of 2 m and above it an oil of specific gravity 0.9 for a depth of 1 m. Find the pressure intensity (i) at t...

Energy Systems (Solved Numerical Problems)

Wind at 1 standard atmospheric pressure and \({15^0}C\) has velocity of 15 m/s, calculate (i) the total power density in the wind stream (ii) the maximum obtainable power density (iii) a reasonably obtainable power density (iv) total power (v) torque and axial thrust Given: turbine diameter = 120 m, and turbine operating speed = 40 rpm at maximum efficiency. Propeller type wind turbine is considered. (AMIE Winter 2023) Solution For air, the value of gas constant is R = 0.287 kJ/kg.K 1 atm = 1.01325 x 105 Pa Air density \(\rho  = \frac{P}{{RT}} = \frac{{1.01325x{{10}^5}}}{{287}}(288) = 1.226\,kg/{m^3}\) Total Power \({P_{total}} = \rho A{V_1}^3/2\) Power density \(\begin{array}{l}\frac{{{P_{total}}}}{A} = \frac{1}{2}\rho {V_1}^3\\ = \frac{1}{2}(1.226){(15)^3}\\ = 2068.87{\mkern 1mu} W/{m^2}\end{array}\) Maximum power density \(\begin{array}{l}\frac{{{P_{\max }}}}{A} = \frac{8}{{27}}\rho A{V^3}_1\\ = \frac{8}{{27}}(1.226){(15)^3}\\ = 1226{\mkern 1mu} W/{m^2}\end{array}\) Assuming eff...

Design of Electrical Systems (Solved Numerical Problems)

Important note There is something wrong with this question paper. It seems that instead of "Design of Electrical Systems" the IEI has given problems from "Electrical Machines". You should raise a complaint to director_eea@ieindia.org in this regard. Numerical A 120 V DC shunt motor draws a current of 200A. The armature resistance is 0.02 ohms and the shunt field resistance is 30 ohms. Find back emf. If the lap wound armature has 90 slots with 4 conductors per slots, at what speed will the motor run when flux per pole is 0.04 Wb?​ (AMIE Summer 2023, 8 marks) Solution The back EMF (E b ) of a DC motor can be calculated using the formula: E b = V - I a R a   Given: V = 120 V I a = 200 A R a = 0.02 ohms Substituting the values into the formula: E b = 120 − 200 × 0.02 = 120 − 4​ = 116 V Now, let's calculate the speed (N) at which the motor will run using the given flux per pole (φ p ). The formula to calculate the speed of a DC motor is: N = 60×E b /(P×φ p ) Wh...