1-Fill in the space with a suitable ward :
DC– astable – heavily – reverse – cathode – AC – lightly–saturation – regulator – electrons
bistable – normally – holes – cut off .
---------------------------------------------------------------------------------------------------------------a)The minority carriers in a P- type semiconductor materials are …………… .
b)Zener diode works in the ................ biase and used as voltage ................. .
c)The power supply converts ………….. to…………….. .
d)In the BJT the collector region is ................. doped , the base region is………..doped .
e)A switching transistor operates in a …………... and ……………..regions .
f)………… multivibrator produces an output square wave without requiring an input signal .
2Choose the correct answer for the following questions :
1-In a semiconductor diode the region near the PN junction consisting of positive and
negative ions is called :
a)Diffusion area .
b)Recombination zone .
c)Depletion layer.
d)Neutral zone .
2-The small variation in the output voltage of a DC power supply is called :
a)Average voltage .
b)Ripple voltage .
c) DC voltage .
d)Residual voltage .
3-The output frequency of a full wave rectifier with a 100HZ sine-wave input :
a)50 HZ
b)25 HZ
c)100 HZ
d)200 HZ
4-The number of valence electrons in both silicon and germanium is :
a)Tow
b)Four
c)Eight
d)Eighteen
1
5-The average value of the 200V peak applied to the half wave rectifier is :
a)54.9V
b)70.6V
c)31.8V
d)63.6V
6-A diode clipping circuit :
a)Insertes a dc level
b)Increases the peak value of the input
c)Removes a part of waveform
d)Gives average value
7-For normal operation of a NPN transistor the base must be :
a)Negative with respect to emitter
b)Positive with respect to collector
c)0V
d)Positive with respect to emitter
8-When a transistor is in a cut-off VCE is equal to :
a)0V.
b)Vcc .
c)0.7V.
d)0.1V.
9-If the DC is 0.99 the DC is :
a)99 .
b)120 .
c)100 .
d)0.01.
10-The N-type in a PNP transistor is :
a)Emitter.
b)Base and collector .
c)Emitter and collector.
d)Base.
2
31- For the circuit shown find :
(2 marks)
Si
a) Diode current (Id) .
b) Load voltage (VL) .
Ge
+
Vdc= 17.4V
-
RL
b)For the shown circuit draw the output waveform and plot the voltages on it .
(2.5 marks)
R
Vo
V0
+10v
3V
Vi
t
-10v
c)Write the name and function for the following symbols : (3 marks)
symbol
name
function
1-
..........................
.............................
2-
...........................
..............................
3-
............................
..............................
3
4The figure shown below is the main stages of DC power supply .
1
2
3
Vi
3
44
IL
+
VL
RL
-
Write these main stages and its function with output waveforms by using the table below :
Stage
Name
Output waveform
1
2
3
4
4
Function
55 : 1
For the shown circuit :
Vi = 110 Vrms
a)What type of this circuit ?
..............................................................F= 50 HZ
RL = 1K
b)What is the peak primary voltage (VPRI) ?
........................................................................
........................................................................
c)What is the peak secondary voltage (VPS) ?
........................................................................
........................................................................
d)What is the peak output voltage (VPO) ?
........................................................................
.........................................................................
e)Sketch the output waveform .
f) What is the average output voltage (VOavg) ?
........................................................................
.........................................................................
g) What is the peak output current (IPO) ?
........................................................................
.........................................................................
h)If a capacitance filter 100 F is connected in parallel with the load calculate :
r % = ............................................................
............................................................
5
6a)For the shown circuit :
VS= 24 V
VL= 15 V
R=0.5K
1)Find the value of IL , IT , IZ
2)The power dissipated in the resistance (PR) .
(3marks)
RL=1.5K
R
+
Vs=24V
IT
IL
VZ
-
b)A transistor has collector current 3ma and DC of 0.97 find base current . (2marks)
c) A transistor has base current 0.2 ma and emitter current 8 ma find its DC and DC .
(3marks)
6
RL
7For the shown circuit : (βDC=100)
Calculate IB , IC , IE , VRC ,VCE .
Vcc =+20V
RC

VBB = 4.7V
7
RB
4
8a-Determine which of the following diodes are conducting(forward) and which are
nonconducting(reverse) ?
find also V0 .
(3 marks)
+3V
+2V
VO
+1V
R
b)
2)For the shown circuits :
a)Construct voltage and logic truth table .
b)Determine the logic operation performed .
(6 marks)
+5V
R2
A
V0
B
R1
0V
+5V
+5V
A
B
F
outpu
8
9For the shown circuit :
VCC
RC1
F
R1 
RC2
R2
47
C1
Q1
Q2
D
INPUT= 2 KHZ
C
R
a)What type of this circuit .
...................................................................
b)Draw the waveform of the input and output .
c)Calculate the pulse width (pw) .
...................................................................
...................................................................
..................................................................
d) Calculate the time period (T) .
...................................................................
...................................................................
....................................................................
e) Calculate the frequency of the output (F) .
...................................................................
...................................................................
..................................................................
f) Calculate the duty cycle of the output .
...................................................................
...................................................................
9