Fundamental of Electronics

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  • Topic: Amplifier, Gain, Oscilloscope
  • Pages : 3 (451 words )
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  • Published : May 6, 2013
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Task 3:

In order to modify the circuit that we created in TASK2 by adding the capacitors C1, C2 and C3 and fixing the value of R2 to be 10K, as shown in figure. We were asked to calculate the voltage gain of the amplifier for the two different values of Rc.

Figure 2
Source:
Figure 2
Source:
In this task we used the function generator to produce a sine wave of 30mV and 50mV Vp-p at the frequency of 50 KHz. We connected CH1 to fed this generated signal in the oscilloscope at Vin. In the other hand, Vout should be connected to fed CH2 of oscilloscope. The voltage gain of the amplifier was to be calculated for two different values of RC using the following formulas:

AV = RC/re where re = 25mV/IE
IE = VE/RE where VE = VB – 0.7
VB = VCC *(R2/(R1+R2))
Theorthically :
When Rc = 3.3kΩ VB=3.03v
VE= 3.03 -0.7=2.33v
IE= VE/RE=1.059x10-3 A
re= 25mv/IE= 25/1.059x10-3=23. 60
Av= Rc/re =139.8

When Rc = 3.3kΩ VB=3.03v
VE= 3.03 -0.7=2.33v
IE= VE/RE=1.059x10-3 A
re= 25mv/IE= 25/1.059x10-3=23. 60
Av= Rc/re =139.8

When Rc = 4.7kΩ
VB=3.03v
VE= 3.03 -0.7=2.33v
IE= VE/RE=1.059x10-3 A
re= 25v/IE= 25/1.059x10-3=23.60
Av= Rc/re =199.1

When Rc = 4.7kΩ
VB=3.03v
VE= 3.03 -0.7=2.33v
IE= VE/RE=1.059x10-3 A
re= 25v/IE= 25/1.059x10-3=23.60
Av= Rc/re =199.1

A: B:

The values of VOUT were to be read from the oscilloscope. The experimental voltage gain values were to be calculated using the formula: Av(exp.) = Vout / Vin. All of the calculated and measured values are tabulated in Table 4.

| Rc=3.3kΩ| Rc=4.7kΩ|
Vin| 28mv| 50mv| 20mv| 40mv|
Vout| 7.2v| 4v| 3.83v| 8.12v|
Av ( theoretical)|...
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