1. EXTERNAL GUIDE INTERNAL GUIDE
HOME THEATRE SYSTEM 5.1
A Report submitted by
KOUSHIK NARAYAN.G
RAHUL SIDDHARTHA.T
VIGNESH.J
Under the guidance of
EXTERNAL GUIDE INTERNAL GUIDE
MR.SALIM MRS.HELINA RAJINI SURESH M.E

2. SYSTEM ANALYSIS
DEFINITION: “System used to achieve theatre acoustical effect at home”
EXISTING SYSTEM
Generally Home Theatre Systems are designed to transfer the audio signals from one or more DVD’s to the six speakers including the subwoofer.
For this process amplifiers and low pass filters are used along with channel selection switches.

3. NEED FOR THE NEW SYSTEM
The existing Home Theatre Systems are designed such that they can handle only DVD inputs and they have limited power output .
A Home Theatre System should be capable of transferring two channel Stereo input signals to the 5.1 speakers along with the DVD output signals. The new systems should support high output power.

4. SYNOPSIS
With Home Theater System 5.1 one can enjoy the real acoustical effect as that of a theater in one’s own living place.
The main objective of our project is to design and develop a Home Theater System 5.1 with a DVD input and a 6 channel output.
In this particular Home Theater System 5.1 we use PIC16C72 which acts as an interface and as a switch between the remote and the volume control IC NJW1153.
Based on the functions selected PIC will generate a control data which is given to NJW1153. An 8 bit A/D converter present in the PIC16C72 is used to convert analog signals from the voltage divider (enables the characteristics) circuit into control data in the digital format.
Based on the input control data the NJW1153 performs functions like volume control, tone control and Input selector gain control on the selected input channel.

5. The input channel may be any one of channel A (5. 1), channel B (5
The input channel may be any one of channel A (5.1), channel B (5.1) or the stereo input (2 channel). The output signals from NJW 1153 are amplified using TDA 7265, which is a class AB Dual power amplifier and are given to 5.1 speakers.
In case of subwoofer a II order analog Butterworth low pass filter is used for producing low frequency signals (160Hz) prior to amplification.
The main idea in designing this system is to connect the two channel stereo input along with the DVD inputs to the 5.1 speakers via NJW 1153.

6. SYSTEM SPECIFICATION BLOCK DIAGRAM CH.B 2 CH.STEREO VOLTAGE DIVIDER
CIRCUIT
PIC
16C72
POWER SUPPLY
NJW1153
LED
DISPLAY
AMP
LPF
CH.A 6
CHANNELS

7. Features of PIC 16C72
It is nothing but Peripheral Interface Controller.
Acts as an interface and as a switching circuit between the remote and the volume control IC NJW1153.
Only 35 single word instructions
All instructions are single cycle (200 ns) except for program branches which are two cycles.
Operating speed DC – 20 MHZ clock input
DC 200 ns instruction cycle
A/D module.

8. Features of NJW1153 NJW 1153 is a 6 channel electronic volume IC.
It includes input selector, tone control, volume, mute, input selector gain control, volume output gain control and 3 REC outputs.
Each mode and conditions are set by the 3 wired serial control data.
FEATURES
Operating voltage ±4.5 to ±7.5V
Input Selector (x 8)
REC output ( x3)
Input Selector Gain Control Gain : /-3/-6/-9/-12dB
Volume Output Gain Control Gain : /+3/+6/+9/+12/+15/+18dB
Volume to -100dB/1dBstep, MUTE
Tone Control (Tr & Bs) to ±10dB/1dBstep
Subwoofer output addition to L, R channel output
Subwoofer output ON/OFF control

10. The three signals namely REQ, SCK and data are transmitted from PIC 16C72 microcontroller to the NJW1153 IC via pin 31, 30, 29 respectively.
The clock signal is enabled 0.8 μs later than REQ signal.
Each bit of the data is transmitted during the negative edge of the clock cycle. Thus 16 bit data is transmitted and after transmitting the entire data.

11. PIC as a switching circuit
There are three control signals from the microcontroller to the NJW1153 IC.
The control signals are
REQ
SCK
DATA
Depending upon the control data the operations like
Multi channel selection
Input selection
Tone control treble
Tone control bass
Volume control for 6 channel(5 Speakers and 1 subwoofer)
are performed.

12. Control data of NJW1153 is constructed with 16 bits.
D0-D3 bits are used for indicating chip address.
D4-D7 bits are used for selecting address.
D8-D13 bits are used as data bits.
The selected address ranges from 0000 to 1001.
Volume control one is selected for adjusting the volume of channel 1.
Similarly volume control for all these six channels can be selected using ‘select address’ bits as shown.

13. The input selector gain control & the volume output gain control are selected if the selected address is 0110.
Similarly for the select address of 0111.Tone control treble is selected and for 1000 tone bass is selected.
When the select address is 1001 input selector and multi channel selector is selected.

15. TONE CONTROL-TREBLE/BASS

16. MULTICHANNEL SELECTION &INPUT SELECTION
The multi channel selector selects the
Two channel input signal (stereo inputs)
Multi channel input signal A
Multi channel input signal B

17. AMPLIFIER SECTION
The audio signals that are received from the DVD inputs after passing the NJW 1153 IC is amplified using TDA 7265 before being fed to the 5.1 speakers.
DESCRIPTION
The TDA7265 is class AB dual Audio power amplifier.
One TDA 7265 amplifier is capable of amplifying signals that are destined to two speakers. Hence six speakers in 5.1 system can be amplified using three amplifiers.
The other features supported by this TDA 7265 are:
Wide supply voltage range (up to ±25V ABS Max.)
High output power
Mute (pop free)
Short Circuit Protection
Thermal Overload Protection

18. FILTER CIRCUIT SECOND ORDER ANALOG BUTTERWORTH LOWPASS FILTER
The filter is designed for a cut off frequency of 160 Hz and the gain of the filter is found to be dB.
FC=160 Hz, WC = 2fC=1004.8rad/sec Let c=.33F, R1=5.128k, Rf =3k
On substituting in
Vo / Vin = Ao (1/R2C2)
S2 + (3 – Ao)s + 1
RC R2c2
Gain in db = 20 log |V0|
|Vin|
Gain= dB

19. FLOW CHART YES NO NO YES POWER ON DEFAULT CHANNEL A CHANNEL SELECTION
CHANGE CHANNEL
UPDATE NJW1153
CHANGE
BASS
VOLUME
TREBLE
POWER ON
YES NO NO
YES

20. 2 channel stereo input can be connected to Home Theater System 5.1.
CONCLUSION
FEATURES
2 channel stereo input can be connected to Home Theater System 5.1.
LED display to indicate the status of the device.
Provision of Input Selector Gain control and Volume output Gain control.
ADVANTAGES
The very best advantage is that the 2 channel stereo input can also be connected the 5.1 speakers along with other DVD inputs.
The power output is very high compared to other systems (5000 watts).
Treble, bass, volume control is performed using NJW1153 & PIC 16C72.
Voltage divider circuit is designed to produce unique voltage for each parameter.

21. THANKYOU