Hello guys , I'm a self thought DIY fan , I love making small scale projects , I wanted to make instructables here but didn't have a nice camera to take pictures of the process.Well now I bought a nice camera so its time I start making instructables. Recently I've been into making audio projects , like a home car stereo based system. The last thing I did is what this Instructable will be about or DIY Small Portable 2.1 Speaker. Now since the projects is already complete I will mostly explain how it is done and publish the circuits you need to make, I plan on upgrading this one to make it better ,but not for now at least.At the end I will explain some modifications you could make.
Step 1: Parts You Will Need:
This is the electronic parts you will need :
-2 x PAM8403 Amplifier Boards - 1-2$ each
-2 x TP4056 - Charging Module for 18650 type batteries - 1-2$ each
-1 x DC-DC converters - they are IN 1-5V to OUT 5.1-5.2V - 2-3$ max each
-1 x MP3 Bluetooth Module - around 7-10$
-*1 x capacitor ( I used 0.1uF )
-*2 x 10K Ohm resistors
-*1 x 15K Ohm resistors
Now if you live in a country where it is easy and fast to order stuff from Ebay or Amazon (unlike me) I would recommend getting this stuff from there because at least where I live ( Bulgaria ) these things get a 400-500% or more price increase when sold in some shop.
* I used these for an RC filter for the bass speaker , I will explain that a bit later and give a calculator to calculate what values you will need to get a certain cut off frequency , so maybe you would like to use different values then me.
Everything else :
Well first of all of course you need something to put everything into.In my case I had a box from some old 2.1 speakers and I used the box that was the subwoofer and had the inputs and stuff on the back , but since not everyone will have these I will explain what you need to make a bit further.
-1 x Male USB A jacks
-1m of vinyl that you like - i spend like 2$ for it and only used like 1/3 of it leaving the rest for some other project
-4 x 18650 type batteries ( I got mine from old laptop batteries , will explain that later)
- 2x2 battery holders
-black and red cables (or other color for the V+ and V- )
-cable with 3 smaller cables in it ( for L,R and G for the audio signal) mine were white,brown and green but you prob should get red,white and black but it doesnt matter really , just need to pay attention to what color you use for what.
-small perfboard that you will use for the filter and something like a control board for everything
Options for speakers :
In my case I used some old 2.5 inch speakers from a DVD home theater (the bigger ones one the pictures).
Now since we are using 2 amplifiers - One for Left and Right and the other one for the bass , you could do it like me and only use 1 channel(by mixing the L/R signal from the MP3 module to the amlifier) (1bass speaker) or use both channels (2bass speakers) nice idea if you are gonna use 2 bass speakers would be little 1 inch speaker in the photos.
-1 x little antena for the MP3 module radio ( i didnt put one cuz Ill prob not gonna use the radio)
Step 2: Explaining Some of the Parts
18650 type batteries - now you could always just buy them , but like I said im a DIY fan so I bought 5 second hand laptop batteries , took them apart and from a total of 30 batteries 23 where ok to use.I will post an Instructable I used to discern which batteries are OK and which are for recycle .Where I live these batteries cost around 2$ each , I bought 5 laptop batteries for 2$ each which had 6 batteries in them for a total of 30 , like i said 23 of them were ok so I saved ALOT. Now these 18650 from laptop are after all second hand so they wont have the full capacity they are supposed to have and your result may differ you might get more or less live batteries.
I will explain in the next step how to do a basic testing on your batteries if you decide to get ones from laptop battery like me and not just get new ones.
TP4056 based 18650 charger - I will explain why you need 2 (or more) of these depending on how many batteries you decide to use ,these little modules are meant to charge 1 batteries at a time , I've tried with 2 works fine , but I havent tried with more and I don't recommend it . Ideally I would recommend using 1 module per battery. I used 4 batteries - 2 chargers for every 2 batteries.
DC-DC converter - from 1-5 to 5.1-5.2V step up converter - you need this to power the MP3 module together with the USB A jack . On most of the MP3 modules it says they work on 12V but that is actually the max Voltage they work at before stopping to work PERMANENTLY . It actually works from 5V to 12V.
Step 3: Basic Testing on 18650 Batteries From Old Laptop Battery
There are a ton of videos and instructions on how to do this , but I will explain how I did it , so you can pick to follow my simple (maybe imperfect )way or search for one you like. As you can see in the pictures on this step there are a ton of different types of laptop batteries.From model to model they may contain from 3-4 to up to 10 x 18650type batteries but most common would probably get 4-6 per laptop battery. There are few technicalities to the process of getting the 18650 batteries from used laptop batteries , like checking how much Amp life they have left when fully charged but those require additional electronics to test (I don't have what is needed ,which would be a device that discharges the battery and measures how much amp it outputs before running out and needing recharging ) , so I made my own test. This is what you need to do :
First since you wont ever need the laptop battery again give it hell and disassemble it any way you can (depends on model so I can't give precise descriptions ) , but best would be getting 1-2 screwdrivers (flat head) and trying to pry the battery open where its joints are . You can pry it little by little from each side or just pry it open from one side enough that you can grab the 2 parts of the enclosure and pry it with you hands ( be careful not to hurt yourself ) .
After you manage to open up the enclosure cut any cables going to the batteries so you can take them out. After you've taken them out use pliers or something to remove anything unneeded from the batteries.
After you have cleaned you batteries you are ready to test which are good and which are not.Using a voltmeter set how it's set in the picture measure the voltage of each battery. Now the ones that measure 2,5V or more are probably ok to reuse , the ones below 2,3-2,4V are probably gone to battery heaven ( which means you could try to charge these but I don't advice or recommend this).
When you determine which batteries are for recycling and which will be charged , just charge the ones that measured over 2,5V (I did this by making a temporary charger using 1 of the charging modules like the ones in the 2.1 build) I recommend using a charger that charges slowly because of the things I have read these type of batteries are temperamental and since its unknown for how long the laptop battery you get was unused at least the first charge you make on them should be slow charged.An automatic one is also recommended - meaning that when the charger indicates that the battery is charged it either goes off or goes into trickle charge mode(supplies a really small current to the battery ).
This step I read about the ended up not doing - After you have charged the batteries measure the voltage and write it somewhere - leave the batteries for a few days somewhere with room temperature , then take a measure again , if there isn't any drop the battery is ok to use.
Step 4: Building a Box or Remodeling an Old One(like Me)
I'm not gonna go into a lot of details of how to make a wooden box , I'm just gonna explain what you need to make.Of course this model is based on mine , which as I said I will upgrade and remodel maybe someday.Honestly this is very nice model considering bass sound / isolating left and right speaker sound from the bass / and total size of the box. There are a lot of things you might decide to do differently after I explain everything, so you might not like the size of my box. The box in the pictures is what you basically need to make , its a simple box with an extra piece inside dividing the box in 2 , where you use 1 side for the bass space and a place to put a the MP3 Module and the other side for the left and right speaker , batteries , charging modules and amplifiers (i made that model quickly out of wood floor tiles just to show you guys what you need to make). I recommend using wood as it is the best for audio devices , something not too thin and not too thick , maybe around 5mm to 1cm. And after you make your box IF your using some scrap wood or just dont like how it looks or just like how some kind of vinyl looks you can put the vinyl AFTER you have decided where everything will be and you have made the holes for everything and BEFORE putting anything in the box.
Step 5: Making the Battery Packs
As I mentioned before the TP4056 based chargers aren't meant to charge a lot of batteries at once ( 2 at best ) so if you decide to use my setup you either use 2x 2x 18650 battery holders or 4x 1x 18650 battery holders.I suggest you use the 2x18650 battery holders. If you use 1xbattery holder make them into 2x2 by connecting the +(positive) of each 2 together. Now each charger will charge a set of 2 batteries which is ok.
Step 6: Making the "control Board" (this Is Where the RC Filter Is Too)
I've explained most on the picture. You need to get a small perfboard . Making the connections here is better then soldering cables to each other. You solder the output from the MP3 module from then on the same lines you connect the inputs to the amplifier for the L/R speakers.From then you connect one end of the 2 x 10K Ohm resistors to the L and R on the perfboard , the other end of the resistors you connect together , to that end you connect 1 end of the 15K Ohm resistor , the other end of that resistor connects to the positive end of the capacitor , the negative end of the capacitor connects to the G(ground) from the MP3 module audio signal output.Then the Input of the amplifier for the bass connects to the L/R(left or right input of the amplifier if you are gonna use 1 bass speaker or to both left and right inputs of amplifier if you are gonna use 2 bass speakers) to the +(positive) of the capacitor and the G(ground input of the amplifier) to the -(negative) of the capacitor. This is for the RC filter , with my values of the resistors you get a cutoff frequency(simply explained -the cutoff frequency means the highest frequency your bass speaker will produce) of 79.58Hz (which sounds nice ) now if you want to get a different cutoff frequency you need to change the values of the resistors and capacitor , HERE is a calculator to help you calculate what cutoff frequency you will get with what R and C values.
The other thing you need to make on the perfboard is to connect all the -(negative) ends of all the modules and device together on the board . For the +(positive) ends you can make it like me ( like in the picture) or directly without soldering to the perfboard , but you need to make the same connections.
Step 7: Other Connections You Need to Make
Now you need to solder 2 cables to the Male USB jack to the 5v+(positive) and 5v-(negative) pins , the other ends of the cables you connect to the MP3 module. This USB Jack you connect to connect to the DC-DC converter if you got like the one is used (that has an USB output) , if you got one without an USB output just connect the MP3 module to the DC-DC converter output ( you dont need a Male USB jack).
I've added a basic drawing of how everything connects to everything else.
The other thing you might have to do is connect a 3,5mm female jack if you happen to get a MP3 module that doesn't have an AUX input on the front panel. As far as I know all of these have an audio input. So if you got one that doesn't have an AUX input jack on the front you need to connect one to where the input on it's circuit board is(depends on model , check model schematics ).
Step 8: Suggestions , Tips and Things You Might Wanna Change
So far this is all you need to make a 2.1 Channel Portable Bluetooth,FM,AUX,USB,TF speaker system. I'll give you some ideas you might want to use or add the project.
- In the picture you can see how I mounted my charger modules , this is so the mini USB that are used for supplying V to the chargers are on the back panel , next to each charging module I made a small hole I filled with hot glue gun with transparent silicone , so when you are charging you can see what color is glowing inside ( red for charging , blue for charged ) . But this way you will either have to get a splitter to charge both at once or charge them 1 by 1. Since the charging module has USB and soldering spots for input V(voltage) you can solder cables to both chargers and then to some kind of female USB ( both + (positives) of the chargers to +(positive) of the female USB and same with the - (negative) ) so you can charge them both together.
- I've added a picture with the connections needed if you decide you want to add potentiometers , the one you put before the bass amplifier will be for the Bass and the one before the other amplifier will be for L/R speakers . You could add 1 more pot between the MP3 module output and the control board which will be for total volume. I decided not to use any because Im happy with how it sounds and you can control the total volume from either the MP3 module panel or with the remote control.
Things I plan to get/make for when I decide to upgrade this model which you might wanna do too:
- Try to find Grills for the L/R speakers - it couldn't , well at least without ordering them , so I improvised .
- If you don't already have some home speakers you might wanna use this at home too , not only outside.This is very easily made . You just need an 8 pin on-off-on switch instead of the 4pin on-off in this model (I've put a picture to show you how you need to connect it ) and a 5V 2A(or more A ,but not more then 5V) power source ( some kind of phone charger probably).
Step 9: P.S.
Now I know my design is far from perfect and a lot of people will find something that they don't like or think I haven't done properly and to those I would say "It's possible , after all I'm not an expert" , but in my opinion this is the easiest / cheapest way to make something that sound nice , last more then 1-2hours (like most out of the box bluetooth speakers do) and you can make the design any way you like. Now 3W (the amps max output) ain't a lot , but for something small and cheap these amplifiers are your best option , you won't be able to listen to it from 50m , but its a perfect speaker for camping , fishing trips , plus if you do the switch with 3 positions you can use it at a home system too. This is the basic of what you need to make a system like this one. There are a ton of different ways you can modify my project - like making it so the left and right speaker are detachable from the main body so you can put them like 1-2m away from each other to get a better surround sound.
IF ANYONE NEEDS HELP WITH ANYTHING I VISIT THE SITE REGULARLY SO DON'T BE AFRAID TO ASK ME !!