Tuesday, August 14, 2012

USB Power Jukebox






Thanks :This project was designed by one of our readers " Mr. Sreenath C J".......



INTRODUCTION

This is a USB Power jukebox system without microcontroller.
In this project a USB player has been attached for music enhancement from pen drives/memory cards. It gives lot of comfort to the user since we can operate it at the time of power failure. We can also charge USB power devices/Phones and provides output DC voltages.
In this project consist of 3 sections, Mini ups system, USB power socket and USB audio player and USB power jukebox is a portable system.


BLOCK DIAGRAM






BLOCK DIAGRAM DESCRIPTION





           Standard step down transformer provides 12V of AC used in this circuit. AC output of transformer connected to mini ups circuit. The mini ups circuit provides an uninterrupted power supply to operate 12V, 9V, and 5V DC-powered instruments at up to 1A current. This circuit consists of   LED’s, diodes, zener diodes, battery, resistors & capacitors. The circuit immediately disconnects the load when the battery voltage reduces to 10.5V to prevent deep discharge of the battery. The capacitor C1 provides ripple-free DC to charge the battery.
         The output of mini ups system connected to USB power socket & USB player. Nowadays, many handheld devices utilizes this facility of USB port recharge their built-in battery pack with the help of an internal circuitry. Usually 5V DC, 100mA current is required to satisfy the input power demand.

USB AUDIO PLAYER MODULE





                  



                  USB Player module consists of USB/Memory card slot and music modes or functions can be operated by a remote. It  operates on  5V,250ma DC supply.

















CIRCUIT DIAGRAM


MINI UPS SYSTEM


Fig-1

USB POWER SOCKET



Fig-2





CIRCUIT DIAGRAM DISCRIPTION


MINI UPS SYSTEM


       This circuit provides an uninterrupted power supply (UPS) to operate 12V, 9V and 5V DC- powered instruments at up to 1A current. The backup battery takes up the load without spikes or delay when the mains power gets interrupted. It can also be used as a workbench power supply that provides 12V, 9V and 5V operating voltages. The circuit immediately disconnects the load when the battery voltage reduces to10.5V to prevent deep discharge of the battery. LED1 indication is provided to show the full charge voltage level of the battery. Miniature white LEDs (LED2 and LED3) are used as emergency lamps during power failure at night.

        A standard step-down transformer provides 12V of AC, which is rectified by diodes D1 and D2. Capacitor C1 provides ripple –free DC to charge the battery and to the remaining circuit. When the main power is on, diode D3 gets forward biased to charge the battery. Resistor R1 limits the charging current. Potentiometer VR1 (10K) with transistor T1 acts as the voltage comparator to indicate voltage level. VR1 is so adjusted that LED1 is in the ‘off’ mode. When the battery is fully charged, LED1 glows indicating a full voltage level of 12V.

       When the mains power fails, diode D3 gets reverse biased and D4 gets forward biased so that the battery can automatically take up the load without any delay. When the battery voltage or input voltage falls below 10.5V, cut-off circuit is used to prevent deep discharging of the battery. Resistor R3, zener diode ZD1 (10.5V) and transistor T2 from the cut-off circuit. When the voltage level is above 10.5V transistor T2 conducts and its base becomes negative (as set by R3, VR2 and ZD1). But when the voltage reduce 10.5V, the zener diode stops conduction and the base voltage of transistor T2 becomes positive. It goes into the ‘cut-off’ mode and prevents the current in the output stage. Preset VR2 (22k) adjust the voltage 0.6V to make T2 work if the voltage is above 10.5V.



        When power from the mains is available, all output voltages-12V, 9V and 5V-are ready to run the load. On the other hand, when the mains power is down, output voltages can run the load only when the battery is fully charged (indicated by LED1). For the partially charged battery, only 9V and 5V are available. Also, no output is available when the voltage goes below 10.5V. if battery voltage varies between 10.5V and 13V, output at terminal A may also vary between 10.5V and 12V, when the ups system is in battery mode.

      Outputs at points B and C provides 9V and 5V, respectively, through regulator ICs (IC1 and IC2) while output A provides 12V through the zener diode. The emergency lamp uses two ultra-bright white LEDs (LED2 and LED3) with current limiting resistors R5 and R6. the lamp can be manually switched ‘on’ and ‘off’ by S1.

       The circuit is assembled on a general-purpose PCB. There is adequate space between the components to avoid overlapping. Heat sinks for transistor T2 and regulator ICs (7809 and 7805) to dissipate heat are used.
The positive and negative rails should be strong enough to handle high current. Before connecting the circuit to the battery and transformer, connect to a variable power supply. Provide 12V DC and adjust VR1 till LED1 glows. After setting the high voltage level, reduce the voltage to 10.5V and adjust VR2 till the output trips off. After the settings are complete, remove the variable power supply and connect a fully-charged battery to the terminals and see that LED1 is on. After making all the adjustments connect the circuit to the battery and transformer. The battery used in the circuit is a 12V, 4.5Ah UPS battery.







USB POWER SOCKET


       A USB port, in practice is a capable of delivering more than 100mA of continuous current at 5V to the peripherals that are connected to the bus. So a USB port can be used, without any trouble, for powering 5V DC operated tiny electronic gadgets.


       Nowadays, many handheld devices (for instance, portable reading lamps) utilize this facility of the USB port to recharge their built-in battery pack with the help of an internal circuitry. Usually 5V DC, 100mA current is required to satisfy the input power demand.
Fig. shows the circuit of a versatile USB power socket that safely converts the 12V battery voltage into stable5V.This circuit makes it possible to power/recharge any USB power-operated device, using in-dash board cigar lighter socket of your car.


       The DC supply available from the cigar lighter socket is fed to an adjustable, three-pin regulator LM317L (IC1).capacitor C1 buffers any disorder in the input supply. Resistors R1 and regulate the output of IC1 to steady 5V,
Which is available at the ‘A type female USB socket. Red LED1 indicates the output and zener diode ZD1acts as a protector against high voltage.



PCB LAYOUT




MINI UPS SECTION











FIG-1




USB POWER SECTION
















FIG-2





POWER SUPPLY UNIT



                   All electronics words only with low DC voltage. We need a power supply unit to provide the appropriate voltage supply. In this project a Dc voltage source of 12V is used to run and charge the circuit and regulator IC (7405, 7409) is used provide regulated 5V and 9V supply.



PCB FABRICATION

The PCB fabrication involves the following steps

1. PREPARATION OF THE LAYOUT

       First the circuit is drawn in orcad capture and the layout is prepared by the orcad layout plus as explained in the layout making procedure. From the layout plus the mirrored image of the top layer is printed on the butter paper. Using this, the film can be made and is exposed to the UV. 

2. FILM PREPARATION

        In this process, the negative of the film is made on photogenic film. For this, the printed image of the layout in butter paper is placed over the film and it is exposed to the UV rays from the top so that the film will be exposed to the UV rays in the regions other than the layout. Then the developer solution is made and the film is taken out of the exposure unit and is put in the developer solutions, then the reaction will take place, then the regions not exposed by UV rays will become transparent and the other regions are dark in color. Thus the negative is produced. Then the film is washed in fixing solutions. After that the film is kept for drying.

3. TRANSFERRING OF THE LAYOUT TO COPPER CLAD

          First the copper clad sheet of required size is cut by using cutting machine. Then the sheet is cleaned by using steel scrubber. After perfect cleaning of the board, it is dipped in the photo resist solution so that film of the photo resist is formed on the board. Then the copper clad sheets placed in an oven for sometime, so that the photo resist will fixed to the surface of the board.

           The next step is to form an image of the layout on the copper clad sheet. For that, the negative of the layout is placed over the sheet. Then it is placed on the UV exposure unit so that the UV rays will fall on the photo resist over the board in the regions of the layout where the negative is transparent. Then the board is taken out and put in a developer solution for about 1.15 minutes. After that, the board is washed gently in water for about one minutes so that the chemical reaction take place in the regions exposed by the UV rays. Then the board is washed in a dye so that the dye will be fixed to the layout regions. Thus we get the visible image of the layout on the board. Then check the layout on the board with the actual circuit. If any mistakes, the above processes are repeated. If layout is correct, the board now ready for etching.






4. ETCHING OF THE LAYOUT

         When the board is ready for etching it is placed in the ferric chloride solution. It is checked in regular intervals to prevent over etching and successive damage to the port. After the etching is complete, the board is taken out of the etch and washed in water to remove the excess ferric chloride. Now the copper lines are exposed and hence the body is checked with the magnifying glass to see whether all the lines in the layout are clearly formed now the board is ready for tinning.

5. TINNING

         For tinning, the PCB is cleaned well and the flux is supplied to the surface then it is passed through the tinning machine. In tinning the copper lines are platted with an alloy of TIN & LEAD.

6. DRILLING

         After tinning, the next process is drilling. In this the holes of required sizes are drilled in the PCB wherever needed, using an electrical drilling machine.
SOLDERING

           Soldering is the process of joining two or more similar or dissimilar metals by melting another metal having low melting point.

SOLDERING FLUXES

            In order to make the surface accept the solder readily the component terminals should be free from oxides and other obstructing films. Soldering flux cleans the oxides from the metal. The leads should be cleaned chemically or by scrapping using a blade or a knife. Small amount of lead should be coated on the cleaned position of the leads and the bit of the soldering iron. This process is called TINNING. Zinc chloride, ammonium chloride and rosin are the most commonly used fixes. These are available in petroleum jelly as paste flux. The residues which remain after the soldering may be washed out with more water accompanied by brushing.

SOLDER

              Solder is for joining two or more metals at temperatures below there melting point. The popularly used solders are the alloys of TIN(60%) and LEAD(40%) that melt at 375 deg Fahrenheit and solidifies when it cools. Most of the soldering wires are flux cored type. When such solder wires are used extra soldering flux is not required.      


SOLDERING TOOLS

SOLDERING IRON

               It is the tool used to melt the solder and apply at the joints in the circuit. It operates in 230V mains supply. The normal ratings of the soldering iron are 10W, 25W, 35W, 65W and 125W. the iron bit at the tip of it gets heated up with in a few minutes. 10W and 25W soldering irons are sufficient for light duty works.
Soldering gun: it is a gun shaped soldering tools used especially when more heat is required. Its trigger is a switch which controls the ac power.
Soldering station is an equipment which provides an iron and a control console that controls the temperature. The tip temperature is maintained by a feed back control loop.

DESOLDERING

              It is the removal or solder from a previously soldered joint. Desolder pump is a commonly used device for this purpose. When the solder melts by the action of the soldering iron, a trigger on the desolder pump should be activated to create a vacuum. This vaccum pulls the solder into the tube. 


COMPONENTS PRICE LIST
                                  


COMPONENTS                                                              PRICE  

BATTERY                                                                             450

TRANSFORMER                                                                    60        

LM317                                                                                      12

7805                                                                                          10

USB MODULE                                                                      450

TIP127                                                                                      15

LM3914                                                                                    55                                                            

LOUD SPEAKER                                                                    25

VOLTAGE REGULATOR (7805, 7809)                                10

                                                         





APPLICATIONS

- It can be used for charging mobile phones, iPods etc

- Constant DC Outputs for DC powered devices

- Supports SD/MMC/MS cards for music enhancements
































ADVANTAGES  



ADVANTAGES


- Backup upto 24hours.

-  Portable system



































LIMITATIONS




- Only certain phone supports USB charging


FUTURE SCOPE


-          Small scale USB powered electronic devices can be operated by this system.
-          USB audio player can compatible with other audio devices ,amplifiers etc
-          Upcoming new i-pods requires USB charging



CONCLUSION


                         One of the primary objectives of an engineer is to endeavor to deliver best product or most efficient service at the lowest cost to the end user. System has been tested and was found to meet the expected result.
                   
                         Aim of this project is to design and construct USB power jukebox device. We have accomplished our aim and were successful in creating the device.


BIBLOGRAPHY


-          http://www.circuitstoday.com
-          http://www.electronicsforu.com

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