Altoids Tin Speaker

Yet another Altoids tin speaker project. The speaker, circuitry, a single AA battery and 3.5mm male-male audio cable all fit together in the tin. Power is supplied with a Maxim MAX756 chip with circuitry right from the datasheet (see also the MintyBoost! both here and at ladyada.net) and amplification with an LM386 op-amp chip with circuitry again right from the datasheet (inspired by Make Magazine's Crackerbox Amp).

Anyone undertaking this project should have access to standard tools -- pliers, diagonal cutters, wire cutters and strippers, soldering iron and solder, multimeter, electric drill and brad point bits (more on these later). Experience making PCBs is also required.

Break Out of Your Pod -- Low Fidelity Audio -- High Fidelity Cool

Pictures
Several early commenters have noted the lack of pictures. There are now pictures detailing the preparation of the Altoids tin, battery holder, speaker, switch, audio jack, audio cable, and overall installation of parts and final assembly. There are also several pictures of the board with all of the electronic components installed but there is not a step-by-step walk through of this process. The main image for step 5 (Soldering Parts to PCB) has image notes identifying each of the parts.

If there are any additional pictures that you think would help the construction process, please let me know.

Step 1 Parts

Parts can be obtained from any of a number of electronic suppliers. Substitute as seems reasonable. The only crucial components are the speaker (because it fits so nicely into the tin) and the Maxim MAX756 and LM386 chips (because the board is designed for them). The links following the parts are to DigiKey and All Electronics.

Integrated circuits
1 x U1 -- LM386 audio amplifier DIP -- LM386N-1-ND
1 x U2 -- MAX756CPA DC/DC 3.3/5V DIP -- MAX756CPA+-ND
2 x Ux -- IC socket 8-pin DIP -- A32878-ND

Resistors
1 x R1 -- 10� 1/4W �1% metal film -- 10.0XBK-ND

Capacitors
1 x C1 -- 0.01�F -- 399-4150-ND
1 x C2 -- 0.047�F -- 399-4189-ND
2 x C7, C8 -- 0.1�F -- 399-4151-ND
3 x C3, C5, C6 -- 100�F -- P5152-ND
1 x C4 -- 220�F -- P5153-ND

Inductor
1 x L1 -- 22�H radial -- M9985-ND

Diode
1 x D1 -- 1N5818 Schottky 1A 30V -- 1N5818-E3/1GI-ND

Miscellaneous
Speaker 8�� 1/2W 57mm square (1) GF0576-ND
Battery Holder 1-AA 6" wire leads (1) 2461K-ND
Phone jack stereo 3.5mm (1) MJW-22
Audio cable 3.5mm male-male 12" (1) CB-400
Toggle switch SPDT 1/4" on-on (1) MTS-4

Image of all parts together with image notes identifying each part

Comments

[cboehm3]

in earlier comments you said you could use the lilypad power supply, and it would take out some components. do you know whick compnents you dont need? (sry, im new to this stuff.)

[matth3w]

Take a look at the schematic in step two. The entire upper part contains the components around the MAX756 chip. This chip boosts the ~1.5 volts from the AA battery to a suitable 5 volts for the amplifier chip. The LilyPad pad power supply does the same thing -- 1.5 volts in, 5 volts out. I do not remember the board layout well enough to say which components to remove, but most of the circuitry around each chip "belongs to" that chip. The power supply is at the upper end of the board and the amplifier chip at the bottom. NOTE -- I have not tried this with the LilyPad power supply but appearances suggest it should work.

[cboehm3]

thank you very much!

[drabinowitz]

I love it, unfortunately I am a novice in electronics and I have no idea about anything in circuitry.

[Schooniedude]

how did you put your toggle switch on, because i have one too but can't fiure out how to get it on.

[matth3w]

The part of the toggle switch sticking out through the tin should be threaded. See step 8. Using the nuts and washers that come with the switch, it can be secured fairly firmly (although I find it works loose after a while).

[wrksnfx]

You can use some thread locker tape (less mess than the fluid) you can get it at your local auto parts store and its used to hold bolts in place to keep them from coming loose due to vibration.

[Firebreathing]

So, would this be a way of adjusting the volume? Or would I need some other sort of volume control attached somewhere?

Also, I was considering attaching a LED so that it flashes with the music. Would I be able to fit it (and the larger battery that I would need, I assume) in the tin?

[Focuscar]

Really, wat a nice idea.

[Kanellos]

I would like to make one of these, but I'm kind of a noob and have no idea where to find some of the parts that were marked obsolete or the sites are down. Please post new locations on where to get?

[matth3w]

The essential part that seems not to be made anymore is the MAX756CPA chip that is the basis of the power supply and allows the ATS to run on a single AA battery. A possible replacement (which I have not tried but expect to) is the LilyPad Power Supply (see SparkFun or other places). It provides 100mA at 5V from a single AAA battery and should fit in an Altoids tin. It will replace about half of the components. The rest of the parts are generic and can be found (maybe no longer at the exact pages referenced) at DigiKey, Jameco, Mouser and others. I have had trouble finding the 12" audio cable from AllElectronics but there must be others.

[oad94]

If you were to use the LilyPad Power Supply could you explain how to hook it up to this? And what else you would need?

[Kanellos]

Alright. So really I just have to google the parts or, like flyin muffin said, hit up radioshack?

[A flyin muffin]

RADIO SHACK

[LiLGq]

This is a very clever project, bec. of the IC MAX756CPA this uses a single aa battery not the 9v battery which makes cheaper but my problem is how loud is this amp reaches??

[matth3w]

The ATS definitely will not deafen you. It is louder than the speakers on a modest laptop and quite a bit louder than an iPod Touch (these are my two points of comparison). It is loud enough to fill a room with sound but definitely not overwhelming. Good to travel with as long as the magnet of the speaker doesn't wipe something clean! There are several version of the LM386 which may make a difference. The high gain settings, however, lead more to distortion than volume. Also, the volume on the device being played seems to have a big effect. Early iPods had to be turned up so loud that they distorted the sound even before it reached the amplifier. Newer ones are better.

[LiLGq]

tnx..

[PazzoPazzo]

(removed by author or community request)

[Motts]

Would it be possible to add to and modify this into a sort of mini amp with a headphones jack?

[matth3w]

The ATS is mono which would cut down on its usefulness with headphones. I imagine that you could replace the speaker with a second jack (there would be lots of room without the speaker) for headphone output. To get stereo input and output you would have to put in a second amplifier chip or use one designed for two channels. Better to look into something like the CMoy Pocket Amplifier which is designed as a headphone amplifier, has stereo output, volume control, and is built using perfboard rather than an etched circuit board.

[Motts]

right, good plan. I have dozens of these tins anyway, no point in trying to conserve one. Thanks for the link!

[monopoly_on_37212]

How complicated would it be to use a 1/4 inch jack instead on an 1/8 inch? would you just switch out the jacks or would you have to upgrade the components as well?

[matth3w]

Space considerations would probably make it difficult to fit in a larger 1/4 inch jack. There is little enough room between the speaker and the front side of the tin for the 1/8 inch jack. Other than that, there would be no need to upgrade any components. It might be easier to get a 1/8 to 1/4 adapter to plug in the outside.

[chicken12175]

could you just use a 3.5mm input jack instead of a stereo input and 3.5mm male-male input?

[nomuse]

That's clever, fitting a boost power converter in there. Given the relative efficiencies of boost conversion vs. 7805, it should get the same or better battery life as a 9V (and the batteries are cheaper, too).

[Delta25]

is needed the 9 volt imput or you only need de AA battery?

[JamesGecko]

 What is the audio quality like? Does it sound, say, tinny?

Yes. Somebody had to say it.

[mdmx93]

were did you find the MAX756CPA? ive been looking for it for weeks now and nobody has it in stock...could you give me an alternative to the chip?

[matth3w]

This seems to be a problem :-( It seems like Maxim has replaced the MAX756 8 pin DIP with much smaller packages but the same low input voltage (see the MAX1674). The second version of the Minty Boost uses a different chip but it requires 2 AA batteries, not just one. Mouser has a few of the MAX756 left (as of April 4, 2010) but it seems like a redesign or breakout board so that the smaller packages can be used is in order. You might also contact Maxim directly and ask for a few samples. You never know.

[chicken12175]

is there any way i can use an LM311 chip as the amplifier. can you do a schematic for this chip please as this is the only chip i can get easily. BTW great guide!

[matth3w]

I haven't had experience using the LM311 chip, but a quick survey suggests it's really a comparator and not an amplifier. I would recommend sticking with the LM386-3 (more powerful than the LM386-1) because I know it works :-). The online electronics supply companies will accept small orders, so the parts should be available (I suppose this depends on where in the world you live). Good luck sourcing parts.

[chicken12175]

OK
cheers for the advice and will try to get an LM386 chip

[adumas]

Hi. Love this design.. Quick question...

Going over the schematic one more time, what is J2 on the lm386 diagram?

[adumas]

Oh, thanks.. I was scratching my head over that one...

 We built your circuit, etched out a board and it works great... So we are thinking of making several more...

Have you sent the Eagle layout to a company for etching? And, is the one provided the most current one?

[matth3w]

J1 and J2 are "jumpers". They are just pieces of wire that go on the top of the board (small pieces of green wire visible on the top of the board). It allows me to use the top of the board in a few places without making (or having made) an actual double-sided board. The part in the schematic allows me to connect to wires in the schematic and have something to move around on the actual layout. The wires coming into the jumper on the schematic are set to the same net, so the effect is just having a single wire.

[adumas]

Sorry, but I seem to have directed my reply to myself and I don't know if you got the message. Here it is again - just to be on the safe side...

Oh, thanks.. I was scratching my head over that one...

 We built your circuit, etched out a board and it works great... So we are thinking of making several more...

Have you sent the Eagle layout to a company for etching? And, is the one provided the most current one?

Also, I tried to use the gain feature - I put a 10uf cap, pos to pin 1 and neg to the middle lug of an audio 10k pot; then took one of the other ends of the pot and hooked it to pin8,... I then could control the volume - but the sound quality is not clean... I'm using an ipod as the source... If I don't use the gain and just the volume from the ipod - it is clear... If I lower the sound from the ipod to mid range, and then try to use the gain and increase the volume, then there is distortion... Is that how the gain is supposed to work?

[matth3w]

I am glad you like the project. I had a lot of fun making it. I haven't had boards made because I will never need as many as the minimum quantity and they are quite expensive in small batches (unless someone knows where I can get 5 for $20.00). Also with the drilling of the tin and everything else, it seems like a difficult project to assemble into a kit.

The schematics and board are the most recent version.

I am not sure if what you describe is how gain is supposed to work but it certainly describes how it does work. The early versions were used with a powerful (?) MP3 player and the sound was good at low volume and no gain. Then someone used a wimpy MP3 player and had to crank the MP3 volume up so much that there was considerable distortion. Adding just a single wire between pins 1 and 8 helped a lot. To get good sound you have to strike the right balance between gain and MP3 player volume. I don't think there is a simple answer and I am quite sure I don't understand the complicated one.

[AKninja04]

Why do you wire the input coming from the audio jack to the negative input on the lm386 instead of the positive?

[AKninja04]

Also, where do all of those grounds connect back to? Sorry if these are very novice questions.

[matth3w]

I followed the schematic for the Crackerbox Amp to determine the connections to the LM386. I don't think it matters which input you use. I also think it made the layout slightly easier, but I could be misremembering. The grounds connect back to the battery ground. Look closely at the constructed board for the green wire jumpers. I think one goes from the LM386 area back the the power area. I had to use them because I etched my own board and couldn't make it double sided. This may make it look like there is not a connection back, but there is.