By Dilshan R Jayakody 4S5DRJ

jayakody2000lk@gmail.com

This unit is specifically design to work with PC sound

cards, radio receivers and CD/DVD/Blue-Ray players.

Construction

This system use commonly available electronic

components and subs#tute components can also

use.

Supply voltage and current 12V – 15V (5A)

Output power 2 × 6W + 20W on 4Ω load

Output drive 2 full range speakers and 1 bass woofer

Audio input 1 stereo audio input

Bass Cut/Boost ±14dB

Treble Cut/Boost ±14dB

Addi#onal bass boost up to +35dB, and configurable for both 2 speakers and for bass woofer.

Addi#onal audio op#ons Loudness and bass mix

Table1: Techinical features and specifica�ons of 2.1 channel audio amplifier project.

Introduction

This ar#cle introduces high quality digitally

controlled 2.1 channel analog audio power

amplifier system. This project is mainly based on

TDA7377 AF power amplifier and PIC18F452 8bit

microcontroller. Basic technical features of this

receiver are covered in table1.

For maximum quality we recommended to use

components from same manufacturer. For

example some actual capacitor values and resistor

values are slightly varied from manufacture to

manufacturer, and this cause some minor

unbalances in output of amplifiers.

When soldering the PCB we suggested to

soldering small components such as jumper wires,

resistors first and moving to larger components at

last.

FIg.1: Prototype of 2.1 channel audio amplifier.

Also try to use IC sockets for all the DIP and

TDA7377 ICs. In our prototype all the integrated

circuits except 2 voltage regulators (IC5 - 7805

and IC6 - 7808) are connected to mainboard via IC

sockets.

All the controls, I/O and power terminals and

display modules are connected to mainboard

through wires, and for control and display lines

we recommended to use suitable ribbon cables.

For power and output wires 18-20 gauge mul#-

strand cables are recommended (these wires are

commonly used for automo#ve wirings).

In given PCB design 4 wires need to be installed

for I2C bus and MCU STAND-BY lines. For this,

standard Teflon coated 32-30 gauge wires are

sufficient.

Microcontroller�irmware

andsourcecode

This project is an open hardware project and all

the source codes of PIC18F452 MCU are available

to download at project website.

The source code of PIC18F452 is wriEen using

MikroC for PIC compiler and free version of this

compiler is available to download at

Mikroelektronika[1]

home page.

Currently available firmware is design for 8MHz

clock and other required MCU related seJngs are

listed in table 2.

Compiled HEX file for PIC18F452 is also available

to download at project website.

Configura�on Address Value

0x300001 0x0022

0x300002 0x000F

0x300003 0x000E

0x300005 0x0001

0x300006 0x0081

0x300008 0x000F

0x300009 0x00C0

0x30000A 0x000F

0x30000B 0x00E0

Table2: Required MCU configura�on values

[1]: Mikroelectronika home page is hEp://www.mikroe.com.

MikroC for PIC is available to download at hEp://

www.mikroe.com/mikroc/pic

Testingthesystem

AOer assembling the system it is necessary to

check all the power connec#ons are working

properly in this system. To check power lines

follow the steps in below:

1. Connect both AGND and DGND together and

from here onwards this connec#on is referred

as GND.

2. Unplug TDA7377, TDA7315, LA2650,

PIC18F452 and 1602 LCD module from the

mainboard.

3. Disconnect any audio inputs and outputs.

4. Supply 12V – 14V DC input to GND and V+

lines.

5. Check the voltages between IC pins which are

listed in table3.

If voltage readings are correct, plug all the ICs and

LCD module and hold down the SYSTEM-RESET

buEon and apply power to the system. While

holding the SYSTEM-RESET buEon press

Component Posi�ve lead Nega�ve lead Voltage readings

TDA7377 socket 13 9 need to be same as supply

voltage (= 12V – 14V)

TDA7377 socket 3 8 need to be same as supply

voltage (= 12V – 14V)

TDA7315 socket 2 3 between 7.8V to 8.2V

LA2650 socket 14 6 between 7.8V to 8.2V

PIC18F452 socket 32 31 between 4.8V to 5.1V

PIC18F452 socket 11 12 between 4.8V to 5.1V

1602 LCD connector 2 1 between 4.8V to 5.1V

Table3: Voltage readings for audio ICs and microcontroller.

POWER ON/OFF buEon and turn on the system.

Once you got the LCD on, release the SYSTEM-

RESET buEon and adjust the controls and check

the audio outputs.

AOer firmware update or at ini#al run, pressing

the SYSTEM-RESET buEon is essen#al to avoid any

damages to speakers due to high volume levels.

FIg.2: Bo(om side wiring and layout of prototype

amplifier PCB.

Volume Rotate to increase / decrease the volume

Bass

Press

Bass level

Press

Rotate to increase / decrease

Press

Treble

Rotate

Treble level

Press

Rotate to increase / decrease

Press

Loudness

Rotate

Press

Press

Loudness ON → Loudness OFF

Rotate

Balance

Rotate

Press

Press

LeO → LeO+Right → Right

Rotate

Subwoofer

Rotate

Press

Subwoofer ON → Subwoofer OFF

Rotate

Press

Bass Mix

Rotate

Press

Press

Sub Gain

Rotate

Subwoofer level

Press

Rotate to increase / decrease

Press

Bass Mix ON → Bass Mix OFF

Rotate

Bass Add

Rotate

Bass addi#on level

Press

Rotate to increase / decrease

Press

Return

Rotate

Rotate

Press

Menusystemde�inedincurrentversionof�irmware

Partslist

C1, C2 15pF

C12, C13 0.0027µF/50V

C14, C15, C16, C17 0.039µF/50V

C6, C7, C8, C9, C10, C11, C34 0.1µF/50V

C25, C26 0.22µF/50V

C27 0.47µF/50V

C19, C23, C24, C31, C32, C33 1µF/16V

C3, C4 2.2µF/16V

C18, C20, C21 4.7µF/16V

C5 22µF/16V

C22, C35 47µF/16V

C30 47µF/25V

C36 1000µF/25V

C28, C29 2200µF/25V

R2 330Ω

R1 2.2KΩ

R8, R9 4.7KΩ

R6, R7 5.6KΩ

R3, R4, R5, R11 22KΩ

R10 1MΩ

Q1 8.00MHz HC49U Crystal

T1 2SC945

IC1 PIC18F452

IC2 TDA7315

IC3 LA2650

IC4 TDA7377

IC5 L7805

IC6 L7808

S1 4Pin OMRON tac#le switch

S2, S3 2Pin push ON switch

ROT1 360˚ Rotary Encoder with push

buEon

LCD1 1602 - 16×2 LCD with HD44780

base controller

All the resistors are 1/4W carbon film type.

All capacitors which range between 0.0027µF to 0.47µF are Mylar capacitors.

Troubleshooting

The most common problem can occur in this

amplifier system is no audio from the power

amplifier IC. The most possible reasons are excess

supply voltage (which is above 18V) or short

circuits in output terminals of amplifier. TDA7377

is equipped with several protec#on features and

state of the protec#on system can be monitored

through Pin 10 of TDA7377 IC.

Second most common issue is LCD with 16×2

boxes. This occurs due to ini#aliza#on problems

of HD44780 controller. A common reason for this

issue is wrong wiring or faulty PORTD outputs.

If LCD output is too light (or dimmed), change the

value of R1 (2.2KΩ) resistor. We set this value for

commonly available Blue/White 1602 LCD

module.

SYSTEM-RESET

MODE / OPTIONS / VOLUME CONTROL

LEFT-SPK (4R)

RIGHT-SPK (4R)

SUB-SPK (4R)

C36 need to be located near IC4

C34 need to be located near IC5

C35 need to be located near IC2

IC4, IC5 and IC6 need separate sufficient heat-sinks

15V

- 5A

DC

INP

UT

PO

WE

R O

N/O

FF

AU

DIO

MU

TE

J2, J3 - 8R Tweeter and Woofer pairs connected in series

J4 - 4R 100W Bass Woofer

PIC18F452

+5V

+5V

DGND

8.00MHz

15pF

15pF

DGND

LCD-HD447803-HOLES16X2-3-HOLESDGND

+5V

2.2K

DGND

330R

+5V

2SC945

DGND22K

22K

DGND

+5V

22K

DGND

EC

12_S

W

EC

12_S

W

DGND

TDA7315

2.2M

FD/1

6V

2.2M

FD/1

6V

+8V

22MFD/16V

AGND

AGND

0.1M

FD/5

0V

0.1M

FD/5

0V5.

6K

AGND

0.1M

FD/5

0V

0.1M

FD/5

0V5.

6K

AGND DGND

0.1M

FD/5

0V

0.1M

FD/5

0V

AGND AGND

0.00

27M

FD/5

0V

0.00

27M

FD/5

0V

AGND AGND

RD

T103

4

RD

T103

4

DGND

4.7K

4.7K

+5V

AU

DIO

-IN

AGND

LA2650

0.03

9MFD

/50V

AGND

0.03

9MFD

/50V

0.03

9MFD

/50V

0.03

9MFD

/50V

AGND AGND AGND

+8V4.7MFD/16V

1MFD/16V

AGND AGND

AGND

4.7M

FD/1

6V

AGND

4.7M

FD/1

6V

AGND

47M

FD/1

6V

AGND

1M

AGND

1MFD/16V

1MFD/16V

TDA7377

AGND AGND

0.22MFD/50V

0.22MFD/50V

VC

C

0.47MFD/50V

2200MFD/25V

2200MFD/25V

47MFD/25V

AGND

AGND

1MFD/16V

1MFD/16V

1MFD/16V

22K

7805TV 7808T

AGND

VC

C

VC

C

0.1M

FD/5

0V+5

V

47M

FD/1

6V

AGND

+8V

VC

C

AGNDDGND

VC

C

1000

MFD

/25V

AGND

DGND DGND

IC1VDD

VSS

MCLR/VPP1

RA0/AN02

RA1/AN13

RA2/AN24

RA3/AN35

RA4/T0CKI6

RA5/AN47

RE0/RD/AN58

RE1/WR/AN69

RE2/CS/AN710

OSC1/CLKIN13

OSC2/CLKOUT/RA614

RC0/T1OSO/T1CKI15

RC1/T1OSI/CCP216

RC2/CCP117

RC3/SCK/SCL18

RD0/PSP019

RD1/PSP120 RD2/PSP2 21RD3/PSP3 22RC4/SDI/SDA 23RC5/SDO 24RC6/TX/CK 25RC7/RX/DT 26RD4/PSP4 27RD5/PSP5 28RD6/PSP6 29RD7/PSP7 30

1211

RB0/INT0 33RB1/INT1 34RB2/INT2 35RB3/CCP2 36RB4 37RB5/PGM 38RB6/PGC 39RB7/PGD 40

3231

Q1

C1

C2

A

DB0

DB1

DB2

DB3

DB4

DB5

DB6

DB7E K

R/WR

S

VDD

VOVSS

LCD

1

R1

R2

T1

R3

R4

S1

3 124

R5

RO

T1A

AA

BB

CC

RO

T1S

W

IC2INL11

TRIB-L 4

INR6

DGND18 SDA19 SCL20

AGN

D3

VCC

2

TRIB-R 5

OUT-R 16OUT-L 17

LOUD-L 9

LOUD-R 7

BOUT-L13

BOUT-R15

CR

EF1

BIN-L12

BIN-R14

C3

C4

C5

C6 C7

R6

C8 C9

R7

C10 C11 C12 C13

S2

S3

R8

R9

1 J1

IC3INL20

DET.OUT 7

INR1

BOO

ST2

ENABLE3 DATA4 CLK5

GN

D6

VCC

14

LED

8

BASSOUT 9

OUT-R 10OUT-L 11

LPF119

LPF216

LPF313

LPF412

VREF

18

DC

-CU

T17

VCAN

F15

C14 C15 C16 C17

C18

C19

C20

C21

C22 R10

C23

C24

IC4

IN14 OUT1 1

IN25

IN411

IN312

ST-BY7

OUT2 2

OUT3 15

OUT4 14

VCC

113

VCC

23

SVR6

GN

D9

PW-G

ND

8

DIAG 10

C25

C26

C27

C28

C29

C30

1

J2

1

J3

1

J4

C31

C32

C33

R11

IC5

GNDVI1

2

VO 3

IC6

GNDVI1

2

VO 3

C34

C35

J51

C36

HD44780 LCD

A

AB

B

E

E

1234

1

2

1

2

1 21 2 3

112

12

34

123 123

DC 15V INPUT SUB-SPK

LEFT-SPK

RIGHT-SPK

SYSTEM-RESET

1602 LCD DISPLAY

R.E

NC

OD

ER

AUDIO-MUTE

POWER-ON/OFF

IC1

Q1

C1

C2

R1

R2

T1R

3

R4

S1

R5

IC2

C3

C4

C5

C6

C7 R6

C8

C9

R7

C10

C11

C12

C13

R8

R9

J1

IC3C14

C15

C16

C17

C18

C19C20

C21

C22

R10

C23 C24

IC4

C25

C26

C27

C28

C29

C30

J2J3

J4

C31

C32

C33

R11

IC5

C34

C35

J5

C36

J8

IC6

SV1

J6

J7PIC

18F4

52

8.00

MH

z15pF

15pF

2.2K

330R

2SC

945

22K

22K 22K

TDA

7315

2.2MFD/16V

2.2MFD/16V

22M

FD/1

6V

0.1M

FD/5

0V

0.1M

FD/5

0V

5.6K

0.1MFD/50V

0.1MFD/50V

5.6K

0.1M

FD/5

0V

0.1M

FD/5

0V0.

0027

MFD

/50V

0.00

27M

FD/5

0V

4.7K

4.7K

AUDIO-IN

LA26

50

0.039MFD/50V

0.039MFD/50V

0.03

9MFD

/50V

0.03

9MFD

/50V

4.7M

FD/1

6V

1MFD/16V4.7MFD/16V

4.7MFD/16V47MFD/16V

1M

1MFD/16V1MFD/16V

TDA7377

0.22

MFD

/50V

0.22

MFD

/50V

0.47MFD/50V

2200MFD/25V

2200MFD/25V

47M

FD/2

5V

1MFD/16V

1MFD

/16V

1MFD

/16V

22K

7805TV

0.1MFD/50V

47M

FD/1

6V

1000

MFD

/25V

7808TV