Lab Report 6

SEMESTER 1 SESI 2011/2012

SFE 3013

BASIC ELECTRONICS

LABORATORY REPORT

NAMENUR HAFIZAH BT ABDUL HADI D20091035072

SITI NORAMIRA BT MOHMAD NOOR D20091035073

DATE 29 NOVEMBER 2011

LECTURER DR BAKAR

Experiment 6 : Transistor Amplifying Circuit

Objectives :

1. To understand the basic characteristics of CE amplifying circuit.

2. To understand the meaning of three modes of operation of the transistor, and

transistor operating.

Procedures :

(A) Experiment for CE Amplifier – Fixed Biasing

1. First, the module KL-23003 is fixed in the KL-21001 Linear Circuit Lab, then the block

marked 23003- block a is located.

2. The short-circuit clip jumper are inserted by referring to Figure 6.1 and the short-circuit

clip jumper arrangement diagram in Figure 6.2.

3. The Ammeter is connected to measure Ib, Ic.

4. VR4 (1 MΩ) is adjusted so that Ib ≈ 0 A (approximately) then the Ic value is viewed.

5. VR4 (I MΩ) is adjusted so that Ic reaches maximum (Ic sat), the Ib value is viewed.

When Ic is saturated, VR4 is adjusted so that Ib increased correspondingly.

6. VR4 is adjusted and Voltmeter is used to measure Vbe and Vce (out) so that Vce=1/2

Vcc, then Vbe, Vce are viewed and recorded.

7. Signal generator in the input terminal (IN) is connected and Oscilloscope (AC position)

is connected to the output terminal (OUT), then signal generator is adjusted so that the

oscilloscope can display maximum non-distorted waveform of 1 kHz sine wave and

recorded.

8. When the maximum non-distorted waveform is generated at OUT, Oscilloscope is used

to measure input signal, then recorded make.

9. The input signal is remained unchanged and VR4 (1 MΩ) is adjusted, then the output

waveform is viewed if it is distorted.

10. The result is recorded in Table 6-1

(B) Experiment for CE Amplifier - Emitter Self-Biasing

1. The short-circuit clip jumper are inserted by referring to Figure 6.3 and the short-circuit

clip jumper arrangement diagram in Figure 6.4.

2. The Ammeter is connected to measure Ib, Ic.

3. VR1 (1 kΩ) is adjusted to 0Ω.

4. VR4 (1 MΩ) is adjusted so that Ib ≈ 0 A (approximately) then the Ic value is viewed.

5. VR4 (I MΩ) is adjusted so that Ic reaches maximum (Ic sat), the Ib value is viewed.

6. When Ic is saturated, VR4 is adjusted so that Ib is increased, then Ic (sat) is viewed if it is

increased correspondingly.

7. VR4 is adjusted and Voltmeter is used to measure Vbe and Vce (out) so that Vce=1/2

Vcc, then Vbe, Vce are viewed and recorded.

8. Signal generator in the input terminal (IN) is connected and Oscilloscope (AC position)

is connected to the output terminal (OUT), then signal generator is adjusted so that the

oscilloscope can display maximum non-distorted waveform of 1 kHz sine wave and

recorded.

9. When the maximum non-distorted waveform is generated at “OUT”, Oscilloscope is used

to measure input signal, then recorded make.

10. The input signal is remained unchanged and VR4 (1 MΩ) is adjusted, then the output

waveform is viewed if it is distorted.

11. VR1 (1 kΩ) is adjusted to maximum.

12. Step 7,8,9, and 10 are repeated.

13. The result is recorded in Table 6-2

(C) Experiment for CE Amplifier – Bias Independent of β Value

1. The short-circuit clip jumper are inserted by referring to Figure 6.5 and the short-circuit

clip jumper arrangement diagram in Figure 6.6. C2 is connected.

2. The Ammeter is connected to measure Ib, Ic.

3. VR2 (10 kΩ) is adjusted so that Vc (out) = ½ Vcc, then the Ic and Ib value is viewed.

4. When Vc = ½ Vcc, the voltmeter is used to measure Vbe.

5. Signal generator in the input terminal (IN) is connected and Oscilloscope is connected to

the output terminal (OUT), then 1 kHz sine wave of signal generator is adjusted so that

the oscilloscope can display maximum non-distorted waveform output.

6. The input signal is remained unchanged and VR2 (10 kΩ) is adjusted, then the output

waveform is viewed if it is distorted.

7. C2 is disconnected (20 µ F), then step 5 and 6 are repeated.

8. The result is recorded in Table 6-3.

Result:

Experiment A. Table 6-1

IC (Sat) (mA) Ib (mA) β VCE (V) VBE (V)3.57 0.023 155 5.95 0.68

When Ib≈0A Ic=2.37A.

When used external resistance 2800KΩ the wave displays at oscilloscopes non-distorted. And the wave will distorted when we adjust the button VR4 to maximum.

Graph

Analysis graph:

Calculation

Voltage peak to peak

Vpp= 20mV x 3.2 Vpp=2V x 5.2 = 0.064V = 10.4V

Frequency

T=1f

f= 1T

f= 10.2mx 4

= 1.25Khz.

Gain Voltage.

Input Output

Av=voppv ipp

Av=10.40.064

= 163

Differentiate the gain voltage by used digital voltmeter and oscilloscope

Diff %= 163−155

155x 100%

=5%.

Experiment B

VR1=0Ω

When Ib≈0A. Ic=3.54mA Vc=1/2 Vcc= 6

Ic=1.10mA Ib= 0.15mA Vbe=0.68

When Ic is saturated the 1b increased correspondingly.

When VR4 is adjust the output voltage is distorted.

Graph

Analysis graph:

Calculation

Voltage peak to peak

Vpp= 20mV x 5.8 Vpp=0.6V x 4.2 = 0.116V = 2.52V

Frequency

Input Output

T=1f

f= 1T

f= 10.2mx 4

= 1.25Khz.

Gain Voltage.

Av=voppv ipp

Av=2.520.116

= 21.7

Differentiate the gain voltage by used digital voltmeter and oscilloscope

Diff %= 23.6−21.7

23.6x 100%

=8.3%.

VR1=maxΩ

When Ib≈0A. Ic=2.68mA Vc=1/2 Vcc= 6

Ic=1.10A Ib= 0.029mA Vbe=0.68

When Ic is saturated the 1b increased correspondingly.

Graph

Analysis graph:

Calculation

Voltage peak to peak

Vpp= 20mV x 6 Vpp=2V x 4.2 = 0.12V = 8.4V

Frequency

T=1f

f= 1T

f= 10.2mx 4

= 1.25Khz.

Gain Voltage.

Av=voppv ipp

Av=8.40.12

= 70

Differentiate the gain voltage by used digital voltmeter and oscilloscope

Input Output

Diff %= 92.4−70

92.4x 100%

=24.2%.

Experiment C

Connect C

Ic=2.83mA Vc=1/2 Vcc= 6 C=22µF

Ib= 0.040mA Vbe=0.68 Vcc=12V

Graph

Analysis graph:

Calculation

Voltage peak to peak

Input Output

Vpp= 20mV x 5.8 Vpp=2V x 4 = 0.116V = 8V

Frequency

T=1f

f= 1T

f= 10.2mx 4

= 1.25Khz.

Gain Voltage.

Av=voppv ipp

Av=8.0

0.116 = 68.9

Differentiate the gain voltage by used digital voltmeter and oscilloscope

Diff %= 68.9−70.75

70.75x 100%

= 2.6 %.

Disconnect C

C=0 Ic=0.14mA Vc=1/2 Vcc= 6

Vcc=12V Ib= 0.04mA Vbe=0.68

Graph

Analysis graph:

Calculation

Voltage peak to peak

Vpp= 20mV x 5.8 Vpp=0.1V x 4.0 = 0.116V = 0.4V

Frequency

T=1f

f= 1T

f= 10.2mx 4

= 1.25Khz.

Gain Voltage.

Av=voppv ipp

Av=0.4

0.116 = 3.45

Differentiate the gain voltage by used digital voltmeter and oscilloscope

Diff %= 3.5−3.45

3.5x 100%

=1.43%.

Input Output

Discussion:

In this experiment we used common emitter to amplifying circuit. We also used NPN transistor

to configuration the potentiometer is used to increase or decreased the emitter base bias

potentials. Which will causes the output voltage to vary. The range at which this transistor

operates is between saturation and cutoff. When the transistor is turned to maximum level, the

condition is called saturation. When it is completely off the condition is called cutoff and when

the transistor is between saturation and cutoff, it operates in a condition called the active region.

Basic Transistor Operation for correct operation, the two pn junctions must be correctly biased

with external dc voltages. The operation of the pnp is similar as that of npn, but the roles of

electrons and holes, bias polarities, and current directions are all reversed.

The figure below shows the correct biasing of a bipolar junction transistor (BJT).

We must note the base-emitter (BE) junction is forward biased and the base-collector (BC)

junction is reverse biased. The forward bias from base to emitter narrows the BE depletion

region. Beside that, The reverse bias from base to collector widens the BC depletion region.then

the heavily doped ntype emitter region is packed with conduction-band (free) electrons.The free

electrons from the emitter diffuse easily through the forward biased BE junction into the p-type

base region. In the base, the electrons become minority carriers (like in a forward biased diode).

While the base region is lightly doped and very thin, so it has a limited number of holes because

of that light doping, only a small percentage of all the electrons flowing through the BE junction

can combine with the available holes in the base. These relatively few recombined electrons flow

out of the base lead as valence electrons, forming the small base electron current. Most of the

electrons flowing from the emitter into the lightly doped base region do not recombine, but

diffuse into the BC depletion region. Once here, they are pulled through the reverse-biased BC

junction by the electric field set up by the force of attraction between the positive and negative

ions. Electrons now move through the collector region, out through the collector lead, and into

the positive terminal of the collector voltage source. This forms the collector electron current.

The collector current is much larger than the base current. This is the reason transistors exhibit

current gain.

From graph above:

IE = IC + IB.

We also used same frequency in all experiment. But our output voltage value is not same. This is

because we used variety mathode to collect the data. The mathode we used is for fixed bias,

emitter self bias and biased independent of voltage gain. In fixed biased we need to find the

value of output at Vce which are from Collector to Emitter. From emitter self bias we need to

record the output voltage at collector, Vc. While in independent of voltage gain we also need to

find the output voltage at collector, Vc but in connect of capacitor or disconnect capacitor. So we

can calcalate the input voltage, output voltage and voltage gain.

Conclusion:

This experiment is transistor amplifier circuit. From this experiment we can conclude that we

understanding the basic characteristic amplifying circuit which we need to collect the output

voltage (Vce) from collector to emitter. From fixed bias Vop-p is 10.4V. from emitter self

biasing Vop-p is 2.52V when VR1 is minimum and 8.4V when VR1 is maximum. Then from

bias independent of β value is 8V when connect to C=22µF and 0.4V when disconnect capacitor.

We also understand the meaning of operation of transistor and transistor operating. We has

discuss about it at discussion.

Reference:

1. Laboratory manual for SFE 3013 Basic Electronic.2. http://hyperphysics.phy-astr.gsu.edu/hbase/solids/trans2.html.3. http://www.wisc-online.com/objects/ViewObject.aspx?ID=SSE3603.