I. PROJECT BACKGROUND AND DESCRIPTION

Think light emitting diodes (LED's) are just for flashlights and cell phone displays? Think again.

Today is an exciting time for those working closely with LED lighting systems, which allow completely

new uses of light. Once relegated to humble indicator lights in electronic devices, it would be able to

synchronize with the beat of the music.

These days, the LED is becoming a preferred light source for much more than simple indicators.

The LED has a simple and strong structure. The beauty of the structure is that it is designed to be

versatile, so we choose it to work with our transistor in this project. The project is fairly simple for

anyone with some electronic skills. “Sync LED to Music” shows how to build a LED lamp that

synchronizes with the beat of the music. It uses some blue LED's that pulses with the bass of the music.

You are listening to your favorite tunes, and you would like some light to blink on the rhythm .

The solution is pretty simple, you solder a transistor together with a switch, some LED’s and a stereo

jack connector and it’s done. The circuit is very customizable because you can keep adding LED's

depending on what voltage your power supply is. The setup of the lights is really up to you. Also you

may need to add a resistor here if your power source is a higher voltage than what your LED's need. The

main thing to consider when choosing layout for the LED's is your audio source and the power supply

you will be using. For this particular project we choose to make it run off a 9v battery and use an

iPod /MP3 for input. The jack of the project will be plug into an audio source and turn it up until you see

the lights. All it is really is using the voltage from the audio input to activate a transistor and turn on the

LED's. After plugging, the LED's will blink to the rhythm of the music. Some players will not be

powerful enough to drive the lights. We suggest any song with a distinctive beat. If you want to listen to

the music as well you need to get a splitter.

Speakers

2-way splitter

Audio

Synchronizing LEDs

Music Source

Music is everything and its evolution can be found everywhere. The existence of iPods and

MP3’s are proof of how much we love music. It also shows how technology grows with it. Music lovers

on the go need to have accessible music and music gadget. And with this “Sync LED to Music”, we can

play our favorite song with LEDs blinking to the rhythm of its beat even on the road. It is portable,

which is good for people who are always on the go. Lights that blink on and off in time with music are

often used by dance clubs to excite the crowd. We can construct big ones so that parties and night outs

would be a lot more fun having speakers with synchronize LEDs in it. But you can create your own

"light show" with just the music coming from an iPod along with “Sync LED to Music”.

DVD player

MP3 player

VCD player

MP4 player

IPOD

PC Tablet

Cellphone

Amplifier (optional)

Speakers

Synchronizing LEDs

II. TRANSISTOR UTILIZED IN THE PROJECT

A TIP31 is a standard type of NPN bipolar junction transistor used for medium power linear

switching applications. A TIP31 is complementary to a TIP31 PNP bipolar transistor. These transistors

are often designated as TIP31A, TIP31B and TIP31C. These additional designations indicate increasing

collector-base and collector emitter voltages. TIP stands for Texas Instruments Power transistor and 31 is

an arbitrary identifier.

The TIP31 pins are numbered from left to right: Base, Collector, Emitter.

Transistor operation:

TIP31 transistors amplify current, for they can be used to amplify the small output current from

a logic IC so that it can operate a lamp, relay or other high current device. In many circuits a resistor is

used to convert the changing current to a changing voltage, so the transistor is being used to amplify

voltage.

Ratings:

Model Vcb

V ce

Ice

Power (Tc = 25°C )

TIP31 40 40 3A 40W

TIP31A 60 60 3A 40W

TIP31B 80 80 3A 40W

TIP31C 100 100 3A 40W

Characteristics:

Parameter Manufacturer Manufacturer Manufacturer

Fairchild Samsung Semiconductor Micro Electronics

Vce saturation 1.2V 1.2V 1.2V

Vbe saturation 1.8V 1.8V 1.8V

Small signal DC current gain (Hfe)

25 25 20

Hfe bandwidth product 3.0 MHz 3.0 MHz 3.0 MHz

Figure 3. Safe Operating Area Figure 4. Power Derating

III. CIRCUIT FLOW EXPLANATION

Schematic Diagram:

9V DC SPST

Left Power

Channel

Right Power

Channel

Circuit Operation

The journey of operation begins with connecting 4 LEDs in the +9V battery. The LEDs are

soldered to a 2-position switch that will connect to TIP31. The intensity transmitted by the audio cord is

taken by TIP31 which causes the LEDs to blink with the music. A small black box is used to install

everything inside. Six holes were made where 4 in the top for LEDs and the switcher and cables on one

hole in each side. To arrange the components easier inside the box, the LEDs were soldered with one

small cable connecting each one.

The 3 pins on the P2 connector consist of left channel, right channel, and the ground pin being

the bigger. The ground from TIP31 must be connected on the other pin from the switcher. If there is any

signal coming from the audio cord, the LEDs will blink or will always be ON if it is in another direction.

Audio Source

Battery

Output

TIP31

Project Construction

The design of the project uses the following materials:TIP31 (NPN transistor), blue LEDs, 220Ω

resistors, audio cable, RCA jack, rocker switch, PCB, 9V battery, battery clip and connecting wires. It

includes soldering 2 LEDs together in series. Connecting the anode (long pin) of the first LED to the

cathode (Flat side/short pin) of the second LED. And the anode (long pin) of the second LED will be

connected to the middle pin of the TIP31 (the collector). It will be repeated for the second part of the

stereo input that is for the remaining pair of LEDs. The anodes of the last LEDs go to positive voltage.

The right pins of the TIP31s (emitter) go to ground. And the remaining pins of the TIP31s (base) go to

the input. Then take the audio cable, strip the ends, and determine which wire is right and which is left.

Red is usually right and white is usually left. Another way to determine the sides is to take a multimeter

and do a connectivity test with each wire and part of the jack. The tip of the jack is right. The middle of

the jack is left. And the bottom of the jack is ground. Decide which set of LEDs will be right and which

will be left. Then connect the corresponding wires to the left pin of the TIP31. The positive part of the

battery clip will be connected to one side of a switch. Then the negative part of the battery clip will be

connected on the right pins of the TIP31s (emitter). And the other side of the switch will be connected to

the resistors. Then mount it all in a case.

Project Behavior

Condition 1: At less audio power output

If the output power produced by the audio source is low the light of the LED is less because in

this case the transistor would not drive enough current to the LEDs.

Condition 2: At high audio power output

When high power output is being produced by the audio source, the LED will eventually follow

the rhythm of the music being played at greater illumination intensity. This is because the transistor will

produce greater current across the LEDs.

Table 1.4

The Light Strength and Type of Music Relationship

The strength of light is dependent also to the type of music being played as shown in the

Table 1.4. To gain the maximum light strength one must play a Hip-hop type of music or any

techno remix.

Output Overview

Previously, the function of our transistor is to amplify current. As we all know in many circuits

a resistor is used to convert the changing current to a changing voltage, so the transistor is being used to

amplify voltage.

This simple project aims to build a circuit that can make the LEDs blink with the sound that

comes out from the audio cord. It synchronizes with the bass sound of the music. Typically, the LEDs

light up whenever the bass hits.

For some additions/modifications for this project we recommend the following:

The first addition is adding an output jack wired in parallel to the audio input wire. Unfortunately

the case we used was a little too small for this.

Different configurations of LEDs. Many people may prefer to use different numbers/colors of

LED. The main thing to be careful of is VOLTAGE that you draw. (Series vs. parallel). The next

step that we are going to try is maybe using a RGB LED.

Transistors. Use an NPN that is rated for the appropriate voltage.

The LEDs in interesting cases. We are going to try mounting them in a pair of portable

speakers.

IV. PICTURES OF THE PROJECT

The Materials

The gathering of materials: starts from the left side( 9V battery, battery clip, 4 blue LEDs, 2

TIP31 transistors, 2 220 Ω resistors, audio cable, jumper wires)

Additional:

Breadboard Testing

cathode (negative) anode (positive) Collector of TIP31

The cathode of the LED will be connected to the middle pin (collector) of the transistor and the anode will be conneted to the resistor.

resistor

switch wire

The other leg of the resistor is connected to the switch.

Base of TIP31

Emitter of TIP31

The switch is connected to the positive node of the battery and the negative node of the battery will be connected to the right pin (emitter) of the transistor. Then the left pin (base) of the transistor is connected to the input.

(+) Positive node of battery

(-)Negative node of battery

blue LED

audio cord

LED lights up, an indication for its operation. If there is any a signal coming from the audio cord, the LEDs will blink.

The Assembling

switch

connecting

wires battery clip

LEDs transistors audio cord

The journey of operation begins with connecting 4 LEDs in the +9V battery. The LEDs are

soldered to a 2-position switch that will connect to TIP31. The LEDs were soldered with one small cable

connecting each one. The 3 pins on the P2 connector consist of left channel, right channel, and the

ground pin being the bigger. The ground from TIP31 must be connected on the other pin from the

switcher.

The Final Product

Top view of the final product connected to an iPod. If there is any signal coming from the audio

cord the LEDs will blink following every beat of the bass of music being played.

V. BILL OF MATERIALS

QUANTITY MATERIAL COST (Php.)

2 TIP31 (NPN transistor) 18.00 each

4 Blue LED 6.75 each

2 220Ω Resistor 0.35 each

1 Audio cable 37.85

1 Plastic case 60

2 RCA jack 19.75

1 Rocker switch 15

1 PCB 2.8

1 9V battery 62

1 Battery clip 5

½ meter wire 2.25

TOTAL COST Php. 230.50

Equipments:

soldering iron

soldering lead

wire cutters/ strippers

mini power drill

screw driver

electrical tape

lactite

VI. REFERENCES

http://www.danielandrade.net/2005/12/06/howto-blinking-leds/

http://www.instructables.com/id/LED-Music-Sync-Lamp/

http://www.kpsec.freeuk.com/components/tran.htm

http://www.electronics-project-design.com/LightingProjects.html

http://www.instructables.com/pages/search/search.jsp?cx=partner-pub-25

http://www.colorkinetics.com/support/tutorials/quickview/index.html

http://en.electronics.org/Light-emitting_diode

http://www.explainthatstuff.com/howtransistorswork.html

http://www.zambotimes.com/archives/26753-Gadgets-With-3GB-Memory-Sometimes-Just-Isnt-

Enough.html

MINDANAO UNIVERSITY OF SCIENCE AND TECHNOLOGY

College of Engineering and Architecture

SYNC LED TO MUSIC

In Partial Fulfillment as a Requirement for ECE 21 (Electronics II)

Submitted By:

DUNQUE, KRISTINE MAE P.

TUBOJAN, JUNEL A.

BUSIS, LOEMIRO B.

Submitted To:

LLOYD JHON B. ESTAMPA, MSEcE

February 2011