# Experiment 10

```ANADOLU UNIVERSITY
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
EEM 102 INTRODUCTION TO ELECTRICAL ENGINEERING
EXPERIMENT 10:
TRANSISTOR CIRCUITS
(FULL REPORT WILL BE GIVEN FOR THIS EXPERIMENT)
Prepared by Prof.Dr. Atila BARKANA
EXPERIMENT 10
TRANSISTOR CIRCUITS
(FULL REPORT WILL BE GIVEN FOR THIS EXPERIMENT)
OBJECTIVE:
To understand the operation of transistors as amplifiers.
PRELIMINARY WORK:
Design an amplifier with Ic ≈ 10 mA, Vc ≈ 5 V, Vcc = 10 V, and a voltage gain of Gv = 20,
assuming β = 150.
INTRODUCTION:
Biasing : To design a voltage amplifier circuit using a transistor, it is necessary to bias the
transistor properly.
Figure 1. Biasing of a transistor
For this, four basic equations are very important.
where β = hFE = Current gain.
for silicon transistors.
(Eq. 1)
(Eq. 2)
(Eq. 3)
IR1 ≈ IR2 ≥ 12 Ib
(Eq. 4)
Once the collector voltage and the collector current are chosen, Ib and Ie can be calculated
knowing the β of the transistor. Then, the resistors RC and RE can be calculated. Then R1 and
R2 are calculated to obtain the desired base voltage VB considering the value of Ib.
Transistor Switch: Transistors can be used as a switch by operating them in saturation and in
cut – off alternately.
vi(t) = 2 cos t where f = 1 KHz.
Figure 2. Transistor as a switch.
Transistor is used in common emitter configuration as in Figure 2. Rb is a protective resistor
which limits the base current. When the transistor is driven hard during the positive half cycle
of the input signal, it goes into saturation causing a very large collector current. Then, because
of the voltage drop in Rc and the saturation voltage VCE of the transistor, VC will be just a few
tenths of a volt. During the negative half cycle transistor base is reverse biased, and hence the
transistor is at cut- off. Collector current is zero and VC is at VCC.
PROCEDURE:
A. Transistor Amplifier.
Figure 3. Amplifier circuit.
A. 1. Biasing : Measure the β of your transistor. Bias the circuit so that VC ≈ 5 V, IC ≈ 10 mA
with VCC = 10 V and a voltage gain of GV =20.
A. 2. Choose the nearest available values to the calculated values above, measure their exact
values, and set up the circuit in Figure 1.
A. 3. Check the voltages VC, VB and VE. If they are not close to your calculations, make
necessary changes in the resistors until you obtain the desired VC and VE.
A. 4. Adjust vi(t) to sinusoidal signal with 0.15 Vrms at f = 1 KHz, and observe and measure
the maximum value Vi .
A. 5. Add the blocking capacitors C1 and C2, and connect vi(t) to the input.
A. 6. Observe vo(t) on the oscilloscope and measure Vo in Vrms, and calculate the voltage gain
.
B. Transistor Switch
B. 1. After adjusting vi(t) = 2 cost, where f=1 KHz, set up the circuit in Figure 2.
B. 2. Draw the input vi(t) and the output vo(t).
C. Write your full report and turn it in to Mr. Mehmet Ko&ccedil; until May 26.
Name: …………………………..
No :…………………………......
Table No:……………………….
EXPERIMENT 10
TRANSISTOR CIRCUITS
REPORT
A. 1. Biasing:
1. Vcc = ……………. V,
Vc ≈ 5 V
= ....................... Ω
= ....................... &micro;A
= ....................... &micro;A
= ....................... Ω
= ....................... V
= ....................... V
= ....................... &micro;A
= ....................... KΩ
= ....................... KΩ
A. 2-3.
R1 = ............................. Ω
R2 = ............................. Ω
RC = ............................. Ω
RE = ............................. Ω
,
Ic ≈ 10 mA
A. 4.
Vi = ............................. Vrms
A. 6.
Vo = ............................. Vrms
..........................
B.2. Transistor switch
Date:
Table No:
Name:
No:
Pre-Lab