Hi, everyone. As you probably noticed I love making projects out of Altoids tins this is already my 2nd Instructable of an altoids tin project ( DIY ALTOIDS SMALLS JOULE THIEF FLASHLIGHT )what can I say, I like the mints and I have many tins laying aroud so let's give them a new life.
I've seen a couple of Instructables on how to turn these small tins into mini portable speakers for the mobile phone, but in many cases they just fit a speaker into the tin without an amplifier circuit so I bet the sound is not really good.
I wanted to make this project as simple and basic as possible so that it can be copied easily and of course improved by anybody who wants to give it a try also I wanted to keep it as cheap as possible.
The heart of this project is the amplifier circuit based on the LM386 which is a power amplifier designed for use in low voltage consumer applications (It can be powered from 5v to 12v). The gain is internally set to 20 to keep external part count low, but the addition of an external resistor and capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200.
Of course you can go to the store and get a pretty good quality mini speaker for probably a bit less than I spent on this project, but where's the fun in that? We're makers let's build our own.
This DIY project is great for beginners in electronics. It´s not complex, It´s very cheap, it´s useful and it´s fun to use! I think I might make it into a Bluetooth rechargeable speaker. But that would be another project.
Step 1: Materials
1 - 3 mm LED – (Color of your choice)
1 - 3 mm LED Holder - Chrome or plastic.
1 - 100 Ohm resistor (Brown-Black-Brown)
1 - Male USB conector.
1 - 3.5 mm Audio Jack
1 - 10 Kilo Ohm Potentiometer
1 - 220 uf Electrolytic Capacitor
1 - SPDT Toggle Switch
1 - 8 Ohm Speaker (Mine is 3 Watt)
1 - LM386 IC
1 - 8 Pin IC Socket
1 - Small PCB board (mine is about 4.5 X 2 cm)
1 Altoids Tin - Flavor of your choice.
Step 2: Tools
Cutter (If you have a Dremel tool is easier)
Double Sided Tape or Hot Glue
Heat Shrink Tube or Electrical Tape
Helping Hand (Optional but very useful)
Step 3: Prepare the Tin
Ok, so if you want a nice and smooth finish this step is probably the hardest part. Take your time and do it carefully if you succeed in this step, you´re halfway gone in this project. I separate the lid of the tin to make it easier to drill and don´t bend the tin in the process.
Grab your drill bits. Find one that is as close to the size of your components. I found out that a 9/11ths sized drill bit works perfectly for the switch an audio jack but try to run on just smaller, because as you know, you can make the hole bigger but you can never make it smaller. I decided to use a scrap block of wood to prevent the tin from caving in and denting.
You may want to mark where you want each hole so measure out all of the internal parts (switch, audio jacks, potentiometer, led and USB conector) and decide on the best placement inside your tin for them all and make sure that everything will fit and nothing will interfere, use a nail or a push pin to leave a little dent this will help you to place your drill in the exact point you want yor hole.Now lightly press as you start drilling let the drill bit do the work for you. If you press hard against the tin you will mangle it.
Step 4: Making the Amplifier Circuit
I won't go over the whole process of soldering all of the connections together it's a very simple circuit with a few number of components. Just follow the schematic (I modified it a little, I didn't add the 0.05 uf capacitor and the 10 ohm resistor conected from pin 5 to ground) and you can see the pictures to help you understan the diagram. I solder extension wires that then will be soldered to the components out of the circuit board( Led, Switch,etc). I highly recomend to mount the circuit in your breadboar before you start soldering to check if everything is working fine.
To make the LM386 a more versatile amplifier, two pins (1 and 8) are provided for gain control. With pins 1 and 8 open the 1.35 kΩ internal resistor sets the gain at 20 (26 dB). If a capacitor is put from pin 1 to 8, bypassing the 1.35 kΩ resistor, the gain will go up to 200 (46 dB). If a resistor is placed in series with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be done by capacitively coupling a resistor from pin 1 to ground.
Don't forget to use heat shrink tubing on all of your exposed connections.
Step 5: Final Assemble - Soldering
We're almost done, to reduce the chance that we get a short you can use some electrical tape or like me you can cut a piece of faux leather and tape it to the bottom of the tin with some double sided tape this will make things appear classy.
Now just mounteverything in their place (I used double sided tape for the speaker an the amplifier circuit) and solder the wires coming out from the circuit board to their corresponding component, if you want you can put some heat shrink tubing so you can insulate your connections after soldering.
I used a pin to make small holes in a circular disposition on the lid of the tin just above the speaker, but this is step is optional.
At this point you can test to see if everything is working. So, is it?
Step 6: We're Done!!
Now just plug in your mobile phone or other Mp3 player and enjoyed your music!! To power your speaker you can use any USB power supply, when I'm in my bedroom I like to use my Power Bank.
This project actually turned out much better than I thought. Obviously it doesn't generate a ton of bass, but the volume it puts out is really surprising, given the size and the simplicity of the circuit. Believe me, It´s really LOUD!!
This is actually not my first Altoids Speaker, I build another one that is powered by a 9 volt battery (as you can see in the last 2 pictures, the red tin) and I'm planning to make another one but using a rechargeable li-ion batterry and of course with the corresponding charging circuit but that'll be a different project and another Instructable if you want.
I recommend this project for all starting DIY people. It works for both kids and adults. It gives you a practical gadget that you can actually use or give as a gift to someone.
It's a great weekend project for beginners and kids, and teaches a lot of electronic basics in the process.
Please let me know what do you think and If you decided to give it a try post a picture in the comments below.