report electronic circuit 1 audio amplifier

Instructor: PhD Nguyen Vu Thang Student’s name: Pham Viet Hoang Student’s ID: 20182951AUDIO AMPLIFIER REPORT:- -----SCHOOL OF ELECTRONIC AND TELECOMUNICATION... List of figures:Figure 1:

Instructor: PhD Nguyen Vu Thang

Student’s name: Pham Viet Hoang

SCHOOL OF ELECTRONIC AND TELECOMUNICATION

Table of Contents

1 Introduction 4

2 Technical specifications 4

2.1 Function 4

2.2 Description 5

2.3 Parameters 5

3 Block diagram 6

4 Block designing 7

4.1 Circuit sketch 7

4.2 Stage 1: Voltage amplifier 7

4.3 Stage 2: Current amplifier 10

4.4 Stage 3: Power amplifier 15

5 Simulation 17

5.1 Simulating process 17

5.2 Simulating result 18

6 Testing with breadboard

7 Layout PCB circuit

8 Conclusion

9 References

List of figures:

Figure 1: Block

diagram……… 6

Figure 2: Audio- amplifying circuit sketch………7

Figure 3: Voltage- amplifying circuit sketch………8

Figure 4: Current- amplifying circuit sketch………9

Figure 5: Power- amplifying circuit sketch……… 10

Figure 6: Circuit simulation on the Proteus software………11

Figure 7: Simulating result on Oscilloscope……….11

1 Introduction

In term 2021.1,I learn about amplifiers and transistors, and now,I design the audio amplifier circuit using BJT for more understanding about its operation and its application

The circuit is capable of amplifying sound

Good sound quality: Clear sound and low noise

Connect with the speaker

be designed to build a full circuit for the audio power amplifier

2.3 Parameters

Power supply: 15VDC

Input signal: 100mV AC (The signal is supplied through the audio jack from our computer or smartphone).

Efficiency: Frequency response: Frequency response is the term used to describe the range of tones that a stereo system can reproduce The range of frequency response should be wide enough (20Hz to 20 KHz) The frequency response should be flat (linear)

Amplifier gain: Combination of the pre-amplifier’s gain and the amplifier

power-3 Block diagram

Our product is divided into 6 main parts: AC input signal, Power supply, Voltage amplifier, Current amplifier, Power amplifier and Speaker or Load

Figure 1: Block

4 Block designing

4.1 Circuit sketch

We use:

• The NPN transistor, BC547 to amplify the small input signal because it is used as

a small signal transistor for VHF (very high frequency) amplifier

• TIP41C, TIP42C to amplify the power of signal because they are power BJT

4.2 Stage 1: Voltage amplifier

We employ the Common-Emitter voltage-divider bias setup in the voltage amplifier circuit The voltage-divider bias setup is less affected by temperature changes, which is why it is more stable than other biasing systems The voltage gain is increased by using the bypass capacitor

Figure 2: Audio- amplifying

DC Mode:

Figure 3: Voltage- amplifying

- Based on the data sheet of BC547, choose:+ The working point of Q is: = 6V ; = 12.5mA+ = 250

- Apply Kirchoff’s voltage law:

- Apply Kirchoff’s voltage law:

= + + +

= x + 0.7V + 1.5V

= 16.34k

= 16k ; = 330

4.3 Stage 2: Current amplifier

I choose emitter – follower Darlington connection configuration to amplifier the current Stage 1 does not amplify the current so much At this configuration, the voltage gain is always approximately 1 I want to use this circuit to amplifier the small current with high gain to increase the Power

= = 0.07 mA

- Stage 2 need to amplify to the value of

Current gain of stage 2 is:

Because the output current of this stage will cause important effect on stage 3 (namely heat effect on T4 & T5), so based on the datasheet of TIP41, I choose the working point of T3 is ( = 6V, = 0.25A) At that point = 55

= - = 15 – 6 = 9V

- From the operation point of , assume that = 0.73V

= 0.25 A

= = = 4.55 mA

= = 4.55 mA

- With = 4.55 mA, based on the datasheet of BC547, choose = 110.

4.4 Stage 3: Power amplifier

The output stage of a Class AB amplifier combines the benefits of both a Class A and a Class B amplifier while reducing the drawbacks of each, such as low efficiency and distortion It outperforms class A and has less distortion than class

B I employ a pair of normal forward biased diodes within the amplifier's biasing configuration to correct for any temperature-related change in the base-emitter voltage (VBE), as illustrated below

- The output device is an 4 – 3W speaker.

- To avoid damage the equipment, we have:

= 4 , = = 2.5W

= = V

= = 3.16V x 4.5 V

The input voltage is 100mV

The maximum voltage gain of the system is:

= =

= 45

- avoid signal distortion, choose 2 = 2 x 4.5 = 9V

Figure 5: Power- amplifying

5.2 Simulating result

6 Testing with breadboard

7 Layout PCB circuit

8 Conclusion

On the breadboard, the output sound is audible, however TIP41 and TIP42 are extremely hot.

I learned how to construct electronic circuits and run simulations as a result of this assignment I may have made a mistake during the procedure, and I am hoping that the teacher can assist me in correcting it Thank you so much for everything.