First Sequence test in Digital And Analog Electronics

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GTHS KUMBO_Electrical Department_First sequence exam…………….…………...…Oct.2012 1

SECTION ONE: TECHNOLOGY

1. Give the meaning of the following abbreviations: ASCII, MSB, LSB, BCD.

2. Define: Semiconductor, Doping, P-N junction.

3. The following information is found on a request list: Diode 1N5401;

VRRM = 100V; IFSM = 200A; VF = 0.2V; IF = 3A; TJ = 150°C. Give the

signification of each indication.

4. Consider the three-input AND gate shown on the figure 1 below with the

chronograms of the signals at the inputs A, B and C.

A

B

C

t

t

t

A

B

C

X

X

t

Figure 1.

a) Draw the chronogram of the output X.b) Suppose that the input A is accidentally connected to the ground (A =0). Draw

the chronogram of the corresponding output X.

5. Consider the logic circuit of figure below.1

2

3

Y

Z

X

S

REPUBLIC OF CAMEROONPeace – Work – Fatherland

……………

GTHS KUMBO/ ELECT DPT

FIRST SEQUENCE EXAM

Class: F36, F26

Option: Electrotechnology

Duration: 04H

Coefficient: 4

Written paper

ELECTRICAL, DIGITAL AND INDUSTRIAL CIRCUITS

No document is allowed except the one given tothe candidates b the examiners.




a) Give the name of each logic gate.

b) For each logic gate, draw the truth table.

c) Give the equation of the output S.

6. Consider the signals u1 and u2 whose wave forms are represented below.

t

t

u 1

u 2

E

E

- E

0

0a T

T

a T T

a) Express the average value of u1 and u2 in function of a and E .

b) Express the effective value of u1 and u2 in function of a and E .

SECTION TWO: ANALOG CIRCUIT

Exercise 1: Alternating current.

Let the following signals: V t u

4

200sin10

; mAt i

4

200sin500

1. Calculate the effective value and the frequency of i and u .

2. Determine the phase difference between i and u .

3. Draw on the same figure phasor diagrams for the signals u and 10i, taking i in

ampere.

4. Deduce the magnitude and the phase of the signal uT = u + 10i.

5. Write the signals u and 10i in polar form. Deduce the expression of

uT = u + 10i in rectangular and polar form.

Exercise 2: AC parallel circuit.

The voltage t u 1000sin275.3 is applied across the terminals A and B of the circuit

below. R1 = R2 = 300Ω; L1 = 0.225H; C2 = 2.5µF

A B

i1

i2

R 1 L 1

C 2 R 2

D

E

F ig u re 2




Determine the complex expression and the magnitude of each of the following

quantities.

1. Impedance of the branch (R1, L1).

2. Impedance of the branch (C2, R2).

3. Intensity of the current i1.

4. Intensity of the current i2.

5. Voltages v AD; vDB; v AE; vEB.

6. Voltage vDE.

Exercise 3: Direct current.

Consider the electric circuit below.

R1 R2

R3I

E

X

Y

Exercise 4: Junction diode.

A test carried out on a diode having the following reference 1N4009 has given the

values recorded in the following table.

V AK(V) 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

I AK(mA) 0 0.2 1 4.3 10.8 19 29 40 51

1. Draw the diode characteristic I AK = f(V AK).

2. Determine the equation of the load line and draw it on the diode characteristic.

3. Determine graphically the bulk resistance RB of the diode and the forward

voltage Vf. Deduce the equivalent electric diagram of the diode.

4. Determine the current flowing in the load and calculate the power dissipated

by the diode.

R

EV A K

IA K

E = 1 . 5 V ; R = 5 0 o h m s

R1 = 2Ω ; R2 = 3Ω ; R3 = 10Ω ; I = 0.5A ; E = 10V.

1. Determine the THEVENIN equivalent

generator viewed from the terminals X and

Y.

2. Deduce the resistance R that will permit a

maximal power transfer if connected at X

and Y. Determine the value of that power.




SECTION THREE: DIGITAL CIRCUIT.

Exercise 1: Logic gates.

The following figure is a digital circuit having four inputs A, B, C, D and one output X.

A

B

C

D

X

1. Determine the expression of the output X.

2. Give the state of the output for ABCD = 1011.

Exercise 2: Digital storage.

A memory can store data whose addresses range from 000016 to FFFF16. Each

memory location store 1byte (8bits).

1. Determine the number of memory location of the computer.

2. Deduce the number of bits that the memory can store.

Exercise 3: Numeration systems.

The information stored in a register of a ROM is given as follows: X = FFDA.

1. What is the meaning of ROM?

2. What is the numeration system used to codify that information?

3. Convert X into binary.

4. Convert X into octal.

5. Convert X into decimal.

6. X is made up of how many bits?

7. Y = FFFF; Compute: X(16) + Y(16), X(2) + Y(2); X(8) + Y(8).

Proposed by Mr. NGOUNE Jean-Paul, PLET.

GTHS Kumbo.

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First Sequence test in Digital And Analog Electronics