Pocket BOOMbox Using ATtiny 85

Hello everyone,

Music have a great role in our every day life. Everybody loves it. The music will change our mood and have ability to keep us healthy. Now in this world the music listening is very simple. Because everybody had smartphones. It can store thousands of songs. I also use this, but some times it did't work (low charge, net browsing,...). That is a good time to think about a portable pocket size music player. In the market it is also available, but that have no speakers, only work with earphones. But I don't like the earphones. So I plan to make a pocket size portable music player with plays songs from the SD card. I name it as "Pocket BOOMbox". I search more about it in the internet and find that a person made a wave music player by using ATtiny micro controller. I love it. So I modify the circuit by adding a power amplifier and a battery charging system to it. Then I strike an another great idea, adding an emergency light to it. It will increase the demand of this portable music player. I love it very much. What is your opinion, Please comment me, What you think ?

For more details about the PCB design and circuit, please visit my BLOG page,

https://0creativeengineering0.blogspot.com/2019/06/diy-portable-pocket-music-player-using.html

The materials needed is given below,

1. SMD components given in the circuit diagram
2. ATtiny 85 or Digispark ATtiny85 development board
3. Tic-Tac box
4. Mobile speakers
5. Li-ion Cell
6. Screws
7. Acrylic paint
8. Nail polisher

The circuit diagram is given above. The brain of the circuit is the ATtiny85 micro-controller. It read the data from the memory card and decode it to the analog signal. The output weak signal is amplified by using the low voltage amplifier IC LM386. It drives the two speakers(connected in parallel). the speakers are obtained from the old mobile phones. The battery here used is the Li-ion cell. It charges by using the USB nano port. The emergency light LED is 3 small SMD LEDs. It is obtained from the mobile phone LCD back-light. The ON/OFF switch is an SMD slide switch. Which has 3 positions ON/OFF/ON. There is an SMD push switch. It is used to move to the next song.

For more details about the circuit, please visit my BLOG,

https://0creativeengineering0.blogspot.com/2019/06/diy-portable-pocket-music-player-using.html

The PCB design is done in the Easy EDA software. It is a double sided PCB. It is made by using the two single sided PCB glued together. The PCB design and the Gerber file are given here.

First we print the PCB layout into a glossy paper (photo paper). In the printing time the 2 sides are print separately and take mirror image of the front side and non-mirror image of the rear side.Then cut the two layouts from the paper. Then mark the same dimension of the layout into the copper clad and cut the 2 pieces from it by using hacksaw blade. Then clean its rough edges to a smooth one by using the sandpaper or file. Then clean the copper side using sandpaper. We successfully done this step.

Here we transfer the PCB layout to the copper clad by using heat transfer method. For this process we need a iron-box for heating it. First we clean the copper clad using sand paper. Then we stick the layout to each copper clad in upside down position and stick it by using insulation tape. Then cover it by using a small piece of paper. Then apply the iron-box to it for a 10-15 minutes. Then wait for cooling it and then immerse it into the water. Then remove the paper in the presence of water by using hand very carefully. After some time we get a good layout transferred copper clad. If you know other alternative methods which is better than my method, you follow that. OK.

This is the time for etching. Etching is the process to remove the unwanted copper from the copper clad. For the etching process we need copper sulfate solution. Take a small amount of copper sulfate powder and add it with water at required concentration. Then place the copper clad in this solution and wait for some hours. Take it from the solution when the etching is completed. Then remove the layout mask by using the sandpaper. Lower concentration is good for etching because it will precisely remove the unwanted copper.

In the previous step we made the copper traces. But in a long time the bare copper traces react with air and this will damage the traces. It will cause the device failure. To avoid this occasion we apply solder mask in the bare traces. Here I apply the solder mask by using a thin layer of solder. But in the industrial method there is a solder mask materials. But the simple way is mine. For this, first we apply the flux through out the PCB and apply a thin layer of solder by using the soldering iron. Then smooth the surface by using a sandpaper, apply it very carefully otherwise it damage the traces. Then clean the PCB by using the IPA solution.

Here we drill all the necessary holes in the PCB. The holes are used to connect the through hole components and for the via connection. Via is used to interconnect electrical connections in the two PCB sides. I use a hand drilling machine for it. I use a small bit for the drilling purpose. After completing the drilling smooth the PCB sides by using the file. Before the drilling process double check the drilling spots with the layout.

I this step we connect via connection by using small component legs conductor. Using this vias we can easily stick the two PCBs into a single double sided PCB without using the glue. First align the two PCBs at the exact position and insert the component legs to the drilled hole. Then solder it one by one. Then cut the extra length of the conductor. Then smooth the cutting ends by using a file. Then check all the connections are good. Our double sided PCB is ready

Here we going to doing the soldering work. All the components are SMD. So good care is needed, otherwise components will damage. Here the ATtiny is not soldered. Because it is soldered only after the programming. For soldering I use a micro soldering iron. The soldering gun is also useful for it. For a good solder joint we need flux. So first paste some flux to the component pads. Then by using the tweezers, place all the components in the right position in the right orientation with respect to the circuit diagram. Then using the micro soldering iron and solder wire solder the component to the pads. First solder the small components like capacitor, resistors,... then solder the large components like ports, SD slots, IC,... After finishing the soldering check all the connections and ensure there is no unwanted short circuits. Then clean the PCB by using IPA solution.

I made a video about SMD soldering using SMD rework station. May be it is helpful for you. The video is given above. please watch it.

It is the time for programming. The ATtiny85 is taken from a Digi-spark development board. For the programming, the program code is in the form of Hex file. So for the programming I use a USBasp programmer. It is an interface board for programming the micro-controller from PC. First I solder some wires from the ATtiny development board and connect it to the USBasp programmer. For the connection I use Vcc, GND, MOSI, MISO, SCK,Reset pins of the ATtiny with the corresponding pins in the USBasp programmer. Then I burn the Hex file to the ATtiny by using the AVR Burn-O-Mat software (I already install the USBasp driver in the computer). Select the micro-controller, Hex file, programmer and the port (given in the image). After successful burning, we going to set the fuses in the micro-controller. Burn the fuses very carefully. The required fuse settings is given in the above image. follow that. The programming is done. The Hex file is attached here. The program is not write by me. It is obtained from the given web-page. http://elm-chan.org/works/sd8p/report.html

Now is the time for desolder the ATtiny micro-controller from the development board and solder in into the music player PCB. For the desoldering I use a hot air gun (SMD rework station). First apply some flux to the micro-controller pins. Then by using hot air gun and the tweezers remove the chip from the board and place it to the music player PCB. Then by using micro-soldering iron and solder wire solder it correctly in the correct orientation. Double check the connections once again. Then clean the PCB using IPA solution. For the desoldering work the above desoldering tutorial video is helpful for you. Please watch it.

If you don't have a SMD rework station then you use the micro-soldering iron for the purpose. But it is little bit harder. Some time it damage the IC. It is not a professional method. I made a tutorial video about it. Please watch it. Link given below,

https://youtu.be/fUvZoXheO9Y

In this step we going to made an enclosure for our tiny music player. I search for a good small sized box which is suitable for it. In my search I find a beautiful tiny one. It is a Tic Tac box. Tic Tac is a brand of small, hard mints manufactured by the Italian company Ferrero. Tic Tac are usually sold in small transparent plastic boxes. So this beautiful tiny transparent box is selected for my music player. First I remove the sticker from the sides. Then I place the PCB inside it and mark the position of the SD card, USB mini, headset ports. The I make holes based on the markings by using soldering iron and other tools. Then finish the holes. Also make a hole in the side for the power switch. So now we finish all the enclosure skeleton works.

Here I doing the painting work. The paint is increase the beauty of our music player. Here for painting I use Acrylic paints. A silver colored acrylic is used. It is available in the powder form. So first make a solution of the powder by mixing it with the binder solution. The mix it very well. Then I clean the plastic box and make some rough surface by using sand paper for better adhesion. Then paint the whole plastic box by using a good quality small brush. After setting apply multiple coats of the paint.

I forgot to make hole for the speaker. Here I made the hole for speakers, switch and the preset. The speaker are select from old mobile phones. These speakers are good. I choose two identical speakers. First mark the speaker dimension and make hole with exact dimension by using cutting blades. Then use a file to precisely adjust the dimension. Then make small holes for the push switch and the preset resistor. Then I connect the speakers to the PCB by using small wires. The speaker are connected in parallel to get more sound. In parallel connection connect the speaker in same polarity. Otherwise cause destructive interference thus decrease the volume. Check the polarity carefully.

Now connect a small Li-ion cell to the PCB and insert a memory card. Ensure that the memory card contain wave files (wave file conversion is discussed in the future steps). If the testing is a success one then insert the PCB inside the enclosure and fix it in the correct position by using screws. Ensure that the switches and the ports are easily accessible. Also solder the wires for the LED light and take it out.

First align the two speakers at its right position and primarily fix it that position by applying the super glue (avoid to enter the glue to the speaker diaphragm). After it apply some hot glue and and apply hot air gun to it to fix very well. Then wait some time for setting it. Then fix the Li-ion cell inside the enclosure by using double sided tape. Then connect the wires to the cell with the correct polarity.

I choose the three small SMD leds preset in the mobile phone LCD display back light. It is fix at the top cap of the Tic Tac box.first make some small holes in the cap and fix it by using the hot glue. The three LEDs are connect in a parallel manner by using small wires. Then connect the wires from the PCB to the LED in the correct polarity.

It is the last assembling step. Here we connect the top part of the enclosure to the box. It is fix in it position by using small screws. Now we complete the assembling procedure.

In this step I add some colors to enhance the beauty of the pocket boombox. For the coloring I use nail polishers of red and violet color. The red color is provided through the edges and the violet is provided to the sides. Also for the speaker I paint the violet color. This is my art work for extra beauty. How is it ? You choose your favorite colors and designs.

The music player only support the wave files. It is an uncompressed file format. The widely available music formats is mp3. So it is necessary that to convert it into the wave format. For this process I use an application named "Switch Sound File Converter" from NCH software family. I use this software, this is very good for the conversion. The essential setting for the conversion is given in the above images. Please observe and follow the settings. Then write the wave music into the SD card. Then insert it into the music player and enjoy.

The Above images shows the final finished products. It is time for enjoy. You copy your favorite songs to the SD card and play it without a problem that where you are.

Hundreds of songs in you pocket....

Its your Pocket BOOMbox.

Thanks for your support.