# Midterm_review by nuhman10

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```									AIT Digital Electronics
Digital Electronics
Midterm Exam Review Sheet

Since the beginning of the year, we have covered 9 chapters in our textbook. However, we have skipped around
somewhat in the book and information has been added that is not in the book. This outline should clarify what
material will be covered on the midterm exam.

All needed equations will be supplied—there should be no reason to memorize equations, but you should know how to
apply them.

Chapter 1: Concept of current (1-2) and voltage (1-3)

Chapter 2: All

Chapter 3: All, except Trouble Shooting a Series Circuit (3-6). For the latter, though you should generally know that
for an open circuit voltage drop=battery voltage and current=0; for a short circuit voltage drop is low (across the
shorted component) and current is generally high

Chapter 4: All, except Trouble Shooting a Parallel Circuit (4-6).

Chapter 5: You should also be able to analyze a simple series-parallel circuit. And on using resistors for circuit design
(e.g. for an LED that had voltage drop (2 volts and current specifications (10 mA). You can ignore Power in a Series-
Parallel Circuit (5-5), The Wheatstone Bridge (5-7-2) and Troubleshooting Series-Parallel Circuits (5-8)

Chapter 7: Know Capacitor Characteristics (7-1),
Capacitors in Combination (7-2) and Types of
Capacitors and Coding (7-3). For a series RC
circuit we learned that the voltage across a
capacitor changes with time as shown at the
right. You should be able to use graphs like the
one shown here to determine the time constant
and use this information to find the state of the
voltage across the capacitor and any time,

Chapter 10: Only basic questions will be asked on
semiconductor material—we are more concerned
with the application of semiconductors rather
than semiconductor physics.

Chapter 11: Operation (11-1-1) and electrical characteristics (11-1-3) of a diode (Figure 11-5) and where a normal diode
and a zener diode (11-2) operate on this curve. Ignore testing of these diodes (11-1-4 and (11-2-2). Light emitting
diodes (11-3). Know how to analyze circuits containing diodes, zener diodes and LEDs. Ignore 11-4.

Power supply circuits: Know the block diagram of a typical power supply (11-5-1). Be able to describe what power
supply ripple would look like. Ignore other rectifier types such as the center-tapped and the bridge rectifers (11-5-3)
as well regulators (11-5-5) and Troubleshooting a DC Power Supply (11-5-6).

Chapter 12: Know basics of transistor operation (particularly NPN) as contained in (12-1-1) and 12-1-3). Ignore
everything in section 12-1-3 and 12-1-4, however you should be very familiar with determining transistor circuit
voltages and currents. You should know most of the information in 12-2; in particular appreciate that the BJT is a
current-controlled device (pg 436) and the regions in which the transistor can operate (ie active or linear region,
cutoff and saturation). [We will see later, in contrast to BJTs that MOSFETs are voltage-controlled devices.]

Digital Electronics Midterm Review Outline                                                     Page 1 of 4
AIT Digital Electronics
Understand how the transistor can be used in an amplification circuit with a voltage-divider base bias. Know: what the
function of a blocking capacitor is. Know the basic characteristics (current and voltage gain and phase) of the three
types of transistor configurations (common-emitter, common-base, and common-collector) and where these might be
used.

IC manufacturing we discussed will not be covered on the midterm exam. That was information I thought many of you
would be interested in but will not assess you on.

Sample Problems:

1. A capacitor, charging resistor and switch were all placed in series with a nine volt battery. A second discharge resistor was placed in
parallel with the capacitor, connected by a switch in series. When the switch was closed the voltage rise shown below was read across
the capacitor. After seven seconds the switch connecting the battery and the capacitor was opened and the capacitor was allowed to
discharge through a discharge resistor in parallel with the capacitor.

Charging and Discharging a Capacitor from a 9
volt source

10
9
Capacitor Voltage, volts

8
7
6
5
4
3
2
1
0
0          5            10          15                 20
Time, seconds

a. Estimate both the charging and discharging time constants from the graph above.                            RC

b. If the capacitor value were 10 F, what is the value of the charging resistor in the circuit?

2. For the transistor circuit shown below: Find the                                                              V1                              Vbe,
18V
Vce, Vbc, Ic, Ib, Vout (assume beta=150) for the
transistor operating above
R2             R1
40kohm         2k ohm

Vout
Q1
C1
2N3904

1uF
V2
0.707V 60Hz 0Deg   R5
7k ohm         R3
500ohm

3.

 6) _______
A)  B) 
C)  D) 

Digital Electronics Midterm Review Outline                                                                                  Page 2 of 4
AIT Digital Electronics

4.
 7) _______
A)  B)  C)  D) 




 8) _______
A)  B)  C)  D) 



10) ______
A) W B) W C) W D) W







11) ______
A)  B)  C)  D) 

8.  12) ______
A)  B)  C)  D) 

9. mF, 40 mF, and 88 mF were connected in parallel, what is the total capacitance? 14)
______
A) mF B) mF C) mF D) mF

10.  15) ______
A)  B)  C)  D) 

11.  =1.2 v; yellow Vf=1.4 v; green Vf=1.7 v and blue Vf=2.8

Digital Electronics Midterm Review Outline                                                           Page 3 of 4
AIT Digital Electronics

A)  B)  C)  D) 

12. For the FET circuit below calculate Vg, Vs, Vgs, Vd, Vs, Vds

Digital Electronics Midterm Review Outline                         Page 4 of 4

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