EXPERIMENT NO.

COLLECTOR CHARACTERISTIC CURVE OF A BIPOLAR TRANSISTOR

I. OBJECTIVE:

To determine the characteristic curves of VCE versus IC for the CE configuration.

II. DISCUSSION:

Transistors are designed with unique characteristics to meet certain application

The following specifications must be considered (a) a brief description of the transistor and
suggested applications, (b) mechanical data including dimensions, biasing, and mounting, (c)
maximum rating, (d) characteristics and other engineering data and (e) transistor characteristic
curves.

TEST CIRCUIT TO DETERMINE AVERAGE COLLECTOR CHARACTERISTICS

As shown in Fig. 7 is a test circuit used for plotting the characteristic curves of an
NPN type the same test circuit with battery and meter polarities reversed could be used. In this
circuit, base current maybe set to a specified value by adjusting R1. The following procedures are
as follows: R1 is adjusted to a reference value of IB, at which value it is desired to plot the curve.
M1 monitors base current and R1 is used to maintain a constant level of IB. M2 measures collector
voltage. Predetermined values of collector voltage are selected and recorded. To obtain a family
of curves, this procedure is repeated for specified values of the base current.
 Ic

Ib

Ib

VCE
R2

R1

S1 S2
Vcc

Figure 7 Test circuit for

Determining Vcs versus Ic

DUAL POWER SUPPLIES

Dual power supplies after a convenient source. Each of the supplies has its own controls
and there is a mode switch for selecting either one or both of the independent supplies. In one
mode, it is possible to control both supplies from the A unit. In that mode, the voltage output of
each supply is exactly the same, both the polarity of each differs and A becomes a positive, B a
negative supply. This feature is convenient when working with differential and operational
amplifiers.

III. MATERIALS
1 – 460Ω resistor 2 – Digital tester
1 – 2N9304 transistor 1 – Variable low voltage DC
1 – 10kΩ, 2W potentiometer
2 – SPST switches
IV. PROCEDURE:
1. Follow the circuit connection, refer to Fig.7. Set VBB at 1.5V and VCC at +3V.
Consider S1 and S2 are open, and then set R1 to 0V. Both digital testers should
be set on the highest milliampere range to protect the meters. Before the power
is applied check the circuit connection and select the tester range.

2. Consider the power is ON. To check the circuit operation, adjust R 1 until low
values of IB and IC are obtained

3. 10A must read by A1 by adjusting R1 and readjust during steps 4 & 5, to

4. Adjust VCC for 0V, that M3 should read zero (VCE = 0 ). Measure and record the
value of IC in Table 7.

5. From Table 7, adjust VCC until the said values of VCE are obtained. Record the
value of IC for each value of VCE in table 7.

6. Adjust VCC for VCE = 0V for R1 IB = 20A. Maintain the value of IB for step
7 & 8.

7. Measure and record the value of IC to table 7.

8. From table 7, adjust VCC until said values of VCE are obtained. Record the
value of IC for each value of VCE. To maintain the value of IB=20A, monitor
IB and readjust R1 if necessary.

9. Repeat steps 6-8 for all the values 1Bas shown in table 7.
V. DATA AND RESULT

IC, mA
VCE, V
IB, μA
0 2.5 5 7.5 10 15 20 25 30
5 0 mA 2.219 2.234 2.339 2.445 2.655 2.865 3.076 3.286
mA mA mA mA mA mA mA mA
15 0 mA 6.417 6.741 7.066 7.39 8.038 8.686 9.334 9.982
mA mA mA mA mA mA mA mA
25 0 mA 10.656 11.199 11.743 12.286 13.374 14.461 15.548 16.635
mA mA mA mA mA mA mA mA
35 0 mA 14.859 15.622 16.385 17.148 18.674 20.2 21.727 23.253
mA mA mA mA mA mA mA mA
45 0 mA 19.035 20.018 21 21.983 23.948 25.913 27.878 29.843
mA mA mA mA mA mA mA mA
55 0 mA 23.188 24.39 25.591 26.793 29.196 31.6 34.003 36.407
mA mA mA mA mA mA mA mA

VI. SIMULATIONS:

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
 VCE

IC

IB

VCE

IC

IB
 VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
VCE

IC

IB

VCE

IC

IB
 VCE

IC

IB

GRAPH
VII. OBSERVATION:
During the experiment, I discovered that VCC is equal to VCE, and that VCE has a
significant impact on the IB value. For example, if you put 0V on that voltage source, the
value of IB will decrease significantly, and the IC will become the negative microampere
value of IB, but if you put 2.5 V on that source, the IC will jump to milliampere. This
experiment 2 enables me to understand the relationship between VCE, VCC, IB, and IC.
Furthermore, even if the resistance value of the potentiometer is reduced, the rise value
of the IC remains constant. That is, the experiment taught me that the greater the IB, the
lower the potentiometer resistance value.

VIII. CONCLUSION:
In conclusion, the collector characteristic of a bipolar transistor is a graphical
representation of collector current versus collector-emitter voltage for a given base current.
It is a basic tool for analyzing the behavior of bipolar junction transistors and designing
circuits using them. The shape of the collector characteristic depends on the transistor
characteristics and operating conditions. In general, this curve is non-linear, showing a
gradual increase in collector current with increasing collector-emitter voltage in the active
region and a sharp increase in the saturation region. The curve has three regions. Threshold
region, active region, saturation region. In the blocking region the transistor is non-
conducting and the collector current is zero. In the active region the collector current is
proportional to the base current and the collector-emitter voltage. In the saturation range
the collector current is independent of the collector-emitter voltage and is limited by the
maximum current capability of the transistor.

IX. QUESTIONS:
1. Draw the circuit of a test circuit, which could be used to determine the average collector
characteristics of a PNP transistor in the CE configuration
2. What is the maximum collector-to-emitter voltage, which may be applied with the base
open? Refer to the transistor data for the 2N3904.

The maximum collector-to-emitter voltage for transistor 2N3904 = 40V

3. From the family of average collector characteristics curves based on the data in table
7, compute the value of beta in the vicinity IB = 40A, VCE = 20V. Show all computations

IE = IB + IC = 0.04mA + 8.686 mA = 8.726 mA

α= = = 0.995

β= = = 200

Another solution for β

β= = = 217.15 ≈ 200