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NOTICE:
The electronics for this project are now available as a kit from Jameco electronics!  Includes a blank PCB and all components/connectors required to build this project. 

DISCLAIMER:  Batteries can be dangerous.  They can deliver high current if shorted out and start fires.  If they are improperly charged it is possible they can explode.  Please do not attempt anything that you are not familiar with and do not feel safe doing, and double-check your work.  I am not responsible for any damage or injury due to misuse of these instructions.


Portable audio is a pain.  Its either a huge boombox that eats D batteries like M&Ms, a bad-sounding iPod dock, or a virtually silent mini speaker set.  None of these will do for a true music lover.  Those who are so inclined and adequately skilled can build one that meets their exacting demands with relative ease.  Now you'll be all set for a trip to the beach or camping. 

A couple years ago while building an amplifier project I accidentally burned out the main driver from a set of Minimus 7 bookshelf speakers.  Radioshack has sold this pair of speakers in various forms for over 30 years, and they are well known for their great sound and low price.  I was quite bummed out that I was left with only one, collecting dust in my storage room, unlikely to ever be of use to me as a Hi-Fi speaker again. 

Then I was inspired to turn it into a portable Hi-fi speaker by installing a rechargeable battery, charger circuit and amplifier.  I had most of the parts needed lying around and managed to put the device together for only $15 additional costs.  A thrifty shopper could probably do the project for around $60.  Great value indeed!

In this guide, I will show you how I converted this speaker into a battery powered portable mini Hi-Fi system.  It works great!
 
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psharp2015 days ago

Hi

Nice project. I'm working on something similar, installing a raspberry pi for music streaming into an old transistor radio. I'm limited on space, as I imagine this build was too, the only way to fit a lead acid battery into the project is with it right up against the back of the speaker.

My question is, did you have the same problem? How close is the battery to the speaker magnet (it's a bit hard to figure out from the picture)? If they are close (as in 2-5mm), does that have any implication for the sound, or could it damage the battery?

Thanks

mattthegamer463 (author)  psharp2015 days ago
It's more than an inch away, but I don't think it would have a problem anyway, as long as it isn't touching the battery contacts.

Lithium polymer batteries for RC vehicles are coming down in price, take a look at implementing one of those to save on weight and get longer battery life. That's what I would do if I was doing it again.
Opparobent18 days ago

What if i want to use 220v ac instead of a battery, what transformer and rectifier do i need? And can you give me some explanation like how much are the output voltage, current and power after passing a transformer. Can I just use a bridge rectifier or you think there is a better method.It would be great if you give me other important details too because Im still new to this kind of stuff. Thank you very much.

mattthegamer463 (author)  Opparobent17 days ago

I recommend you use a 18-20V laptop power adapter. They are cheap, efficient, and easy to use. If you are new to transformers you should definitely be reading lots of theory material and understanding precisely what you are doing, as you know 220V AC can kill you.

Opparobent1 month ago
Can you also teach how to build a crossover? or at least pls give some advices
mattthegamer463 (author)  Opparobent28 days ago
http://www.diyaudioandvideo.com/

This page has many articles, tutorials, and calculators for crossover design and building.

very nice project , ive been looking for this for a long time thanks x)

JKPieGuy1 year ago

(I've tried submitting this question two other times, but for some reason the "Back-Space" button kept on turning the page back, thus loosing what I had wrote.)

Two questions though:

First, if batteries are usually charged about 2 volts above the battery rating, which in this case would 14V for a 12V battery, then why is 18v needed from the power supply?

Second, is it important to use a laptop charger, or can an AC-DC wall adapter with the same rating work? (Because as far as I know, a laptop power brick is just a cleaner supply of DC.)

Please respond back when you have the chance, and I'll really appreciate it. Thanks.

Also, another thing. You had said if we had any suggestions to leave them in the comments. Well I was thinking if you were to add some "Speaker Grill Cloth Fabric" to the front, it help keep the dust out, and prevent things from puncturing the speaker themselves. Plus it would look very nice if you were to use some vintage looking speaker fabric.

mattthegamer463 (author)  JKPieGuy1 year ago

Hi there, the reason for the 18V supply is so that there is some overhead for the charging circuit, since it uses a linear regulator for a constant current source. The 18V also gives the amp a little more overhead and volume capability when plugged in. The laptop supply is just because you can't beat laptop supplies for voltage and current capabilities, for the price. They can also be found cheaply or for free from a dead laptop. The clean voltage is also nice but any supply should do. I removed the speaker cover because it looks way cooler, and it isn't so obvious that its a speaker box when its on there so it isn't as good for pictures. I lost the dust covers a long time ago for this one anyway. Dust covers really doesn't do muc to prevent punctures but does help against UV damage from the sun.

Thanks for returning my question so quickly, I really appreciate it!

Now that you explained why 18V is needed, it makes allot more sence. So basically what you're saying is: Instead of draining the battery while it's charging, the excess voltage powers the amp letting the battery charge steadily. You also have a very good point about the laptop chargers. You can find them quite easily and cheaply also. I also have to agree, it does look cooler seeing the actual speaker instead of a bland black dust cover.

I do plan on building one of these over the summer, but I can't seem to find any good Bookshelf Speakers lying around (and I don't really want to buy any from for say "Best Buy", cause for the price they charge, you minus well just buy a boombox). Though I do have some old car door mount speakers that my Father got a long time ago and never used. Was thinking of getting some plywood and routing that into a speaker box, though I'd probly make it stereo instead of Mono since I have two speakers. I'll make sure to let you know how it goes once I get around to it. I do want to modify the circuit just a tad, by adding an indicator light which would display Battery at full charge.

Question about that though. In order to get a stereo sound, wouldn't I just build two of the speaker amplifying circuits without the two mixing 1K Resistors at R9 and R10?

mattthegamer463 (author)  JKPieGuy1 year ago

Yes, just remove the resistors and send one channel to each circuit. For the full charge indicator, use a NPN transistor and a LED, and a pair of resistors that put 0.7V on the base of the NPN when 12V is coming from the + of the battery. The LED won't light until the voltage becomes 12V. You could use a trimpot in place of two resistors to make it adjustable trigger.

Could you make an instructable on how to incorporate a Radio and Auxiliary device in as well? Built in to the housing that is...
mattthegamer463 (author)  usMudack19981 year ago
Really it wouldn't difficult to do. If you can't imagine how to do it then how will you be able to accomplish it?
ManishS1 year ago
Thanks for sharing! It is superb and so easy to handle...

I would also show you portable electric router..It is so easy to use and easy to handle..

http://www.endicopowertools.com/portable-electric-routers.php

nettro12 years ago
Very cool
gquirino2 years ago
uhmmm what will happen if I failed to build a crossover and instead, directly connecting the tweeter and sub together? if the crossover is really needed can you please teach me how? 'cause im still new on these things and i would like to build this project because im also a music lover and a portable speaker will help me alot..thanks in advanced!! :D
mattthegamer463 (author)  gquirino2 years ago
A simple crossover is very easy to make, it only contains two components.  This tool will help you out http://www.diyaudioandvideo.com/Calculator/XOver/

Without the crossover some speakers can get grumpy about having to try to handle low frequencies (tweeters don't like that) or high frequencies (woofers just plain can't do it) so there's good reason to include one.  Sound quality will suffer without one as well.

dtbingle2 years ago
The kit by jameco with all of the components is either not complete or am I missing something? Unless I completely overlooked something, I don't see the .5 ohm 5w resistor, 1k resistors and has extra 47nf caps in place of the 37 or 39nf caps (can't remember which) in this jameco kit. Am I doing something wrong?
and ,, how it sounds???????
mattthegamer463 (author)  pogodike200!!!2 years ago
It sounds great!
because is very good men
nilnate5192 years ago
what type of Terminal Block was used for the project, looking on digikey and too many options for me to make a well informed decision
mattthegamer463 (author)  nilnate5192 years ago
Hi, The T-block can be any 0.2" (5.08mm) pitch T-block or connector. Digikey part ED2609-ND or similar.
nilnate5192 years ago
I am wondering what speaker and subwoofer to buy to make this a good project. Are these good speakers Tang Band W4-930SF. What about Subwoofer? Also recomend components that would be easy to get at a Radioshack
mattthegamer463 (author)  nilnate5192 years ago
Maybe these will work for you

http://www.radioshack.com/product/index.jsp?productId=10951399&filterName=Price&numProdsPerPage=60&filterValue=%2410.00+-+%2449.99
Also how do you hook up the subwoofer in the circuit and if I just wanted to buy speakers could I make my own inclosure?
mattthegamer463 (author)  nilnate5192 years ago
You will have to design a crossover circuit to filter low frequencies to the subwoofer and high frequencies to the tweeter. Crossover design is not a simple thing to do so I recommend you just get/buy an old speaker to use. Speaker cabinet design is also a pretty math-heavy thing so I recommend getting/buying a speaker for that reason as well.
What are "VCC" "T Block" and "Wi" also how does the battery circuit connect to the speaker circuit.
mattthegamer463 (author)  nilnate5192 years ago
Vcc is the circuit voltage. T-blocks are screw-down wire terminals. I don't know what Wi is or where you got that from.

The circuit schematic is pretty straightforward. There is a switch that disconnects the battery from the charging circuit and hooks it to the amplifier circuit.
brendan9452 years ago
I think as evidenced by the comments here, this is a great jump off point for anyone looking to build a portable audio system. I have been kicking this idea around for a while unsure where to start. This is exactly the kind of instructable I've been waiting for.
Maybe I'm confused but I read through this a couple of time and viewed the PDF. Where are you buying all of the electronics parts from?

Additionally how did you do the PCB? I actually have quite a bit of "blank" PCB but I'm not sure the best method of transcribing/etching onto them. What do you recommend?
mattthegamer463 (author)  johnson.taylor2 years ago
I didn't say where I got my parts since for most people it is up to their preference to get them from a local store, internet, eBay, etc. and people's location determines where they can and can't buy from. Listing sites would be mostly useless. I get my parts from Digikey but almost all these parts are available anywhere that sells electronic components. Even Radioshack should have all this stuff.

I made the PCB using the laser printer and magazine paper iron-on transfer method. Works great and is practically free. Alternatively PCBs can be manufactured in china by internet order for as little as $1 apiece. Here is a guide I loosely follow to do my boards
whizbo2 years ago
I built a slightly larger speaker on the same premise.
http://stories.parts-express.com/stories/2444-en_us/category/Speaker/story/16637/redirect.htm

There are lots of efficient Class T amps out there. That can save you some time. Here's a wonderful review http://www.tnt-audio.com/ampli/tripath_amps_e.html

I went with the The 41HZ AMP-3 and I've been very happy.

Technically mine is portable, but it's not light. Your design looks like a great size. Cool build!!
lil_ricky.jpg
mattthegamer463 (author)  whizbo2 years ago
Thanks, thats pretty great, how long is the battery life at a reasonable volume?

8 hours of great sound, then the base starts to distort a bit and requires the volume to be turned down.
add this
http://www.amazon.com/gp/product/B007R8PVJS/ref=oh_details_o01_s00_i00
cheap and sounds great
i just put this into some earmuffs turned out great
Joe_M2 years ago
I think the amp is a litle like reinventing the wheel. There are some great low cost amps that have a RCA input, volume, tone, and head phone, that would do nicely on that big battery. They are stereo, but I think there are some that can be set to mono, and double the power to one channel.
I love the idea of making your own kick-ass boom box. You could incorporate a cheap mp3 type player, and add any amount of ram of MP3 music, or whatever audio format you like.
mattthegamer463 (author)  Joe_M2 years ago
Yeah definitely. The integrated MP3 player would be great. Deal extreme has some really good looking ones for $10. The amp and battery charge circuit on one board was unnecessary but since I didn't have either as a pre-made or kit type, I just made them myself. Good practice on the PCB making techniques too. Haven't made one that way in over a year.
Elipsit2 years ago
Solid project as per usual. Not sure why there is so much flack about pricing, the main focus of an instructable...is to instruct, which he did quite well.
Trike Lover2 years ago
Interesting project. Your idea of including a rechargeable 12 volt battery is a good one. If I were building it I think I would also make some provision for a cord to connect to an automobile cigarette lighter socket, using a power cord jack with a switch that would disconnect the internal battery and connect the car battery supply. You might also want to include a switch (DPDT, center off?) to give the option of charging the internal battery directly from the cigarette lighter input, bypassing the charging circuit. You would then have the option of internal battery power, external auto battery power, or charging the internal battery.

Another provision that might be useful would be to put in a 7805 regulator alongside the LM317, the output of which would go to a jack where the power cable for an mp3 device could be plugged in (all mine run on 5 VDC at less than 500 mA. Connector choice would be up to the individual; a chassis-mount standard 4-pin USB socket would probably mate with most mp3 player cords. (+5 VDC and Gnd. on pins 1 and 4).

If you wanted to get really "green" on the battery charging side, you might consider purchasing one of the small "battery maintainer" solar panels that put out about 14-15 volts; output power is 1.2 - 1.5 Watts.

I frequently see these on sale for as little as $10. They have built-in car battery-charging circuits, so you could again use a switched cable input jack, with the switch bypassing the internal charging circuit, and connecting the solar panel directly to the battery. If you were having your fun in the sun, one of these would charge the battery without an external power source, and extend your "run time".

If your speaker box was a bit longer, the panel could mount right onto the box. Alternately,, devise a folding stand with a few pieces of stiff wire, or wooden dowels, to align the panel at the best angle for maximum solar capture. Have a couple of clips to hold the panel onto the box side when not in use. These panels work even if placed in the rear window of a car, or on a bicycle carrier rack, so it could continue to charge the internal battery in transit.

Finally, for those who don't want to etch their own boards or build their own amplifier board, single-chip mono amplifier boards with suitable power outputs and input voltage requirements are available on various online auction sites, some for as little as $10. The lazy man's way, yes, but for those with less experience in building circuits, these offer an alternative, and still let the builder do the other parts of the construction.

Just a few thoughts, not meant as a criticism of your very neat and attractive project.
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