Portable Retro Hi-Fi Speaker

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!

Step 1: Parts and Materials

Heres the list of goodies you'll need, and some details about them.

• A bookshelf speaker.  You're going to want something that will work well on only 10-20 watts of power, otherwise the battery life will be very, very short.
• Sealed Lead Acid battery.  I know these are heavy, but they're also cheap and very easy to charge.
• Circuitry.  The full bill of materials is on Step 3.  The circuit is based on the reference design for a TDA2003 10 watt audio amplifier IC and a generic lead acid charging circuit using a LM317 variable voltage regulator, used to control charge current for the battery.
• 18V laptop power supply.  It is important that it is 18V.  The lead acid battery charger circuit needs 18V and the amplifier doesn't like continuous operation above 19V.  Hopefully you can find one of these for cheap or free.  2A or more is plenty of current for this.
• Sheet metal.  Something to fill the hole in the back of the cabinet to make a new control panel out of.
• 2.1mm DC input jack.  For the input power from the laptop supply.
• 3.5mm stereo jack.  For your audio source input.
• Toggle switches.  For switching between wall power (charge) and battery power modes, and for on/off control.
• Potentiometer (optional).  To control volume, if you want the ability to control it separately from your device.  Controlling it from your device will save on your device's battery power, though.  The TDA2003 only uses the power you hear so there is no waste of power having it at maximum volume all the time.
• Chip heatsinks.  Definitely a good idea to add some small heatsinks for the ICs.
• Handle.  Something to make it easy to carry.
• Rubber feet.  To protect the wood and make sure the device doesn't slide away.

Comments

[gquirino]

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]

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.

[dtbingle]

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?

[pogodike200!!!]

and ,, how it sounds???????

[mattthegamer463]

It sounds great!

[pogodike200!!!]

because is very good men

[nilnate519]

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]

Hi, The T-block can be any 0.2" (5.08mm) pitch T-block or connector. Digikey part ED2609-ND or similar.

[nilnate519]

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]

Maybe these will work for you

http://www.radioshack.com/product/index.jsp?productId=10951399&filterName=Price&numProdsPerPage=60&filterValue=%2410.00+-+%2449.99

[nilnate519]

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]

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.

[nilnate519]

What are "VCC" "T Block" and "Wi" also how does the battery circuit connect to the speaker circuit.

[mattthegamer463]

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.

[brendan945]

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.

[johnson.taylor]

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]

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

[whizbo]

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!!

[mattthegamer463]

Thanks, thats pretty great, how long is the battery life at a reasonable volume?

[whizbo]

8 hours of great sound, then the base starts to distort a bit and requires the volume to be turned down.

[tylermeredyk]

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_M]

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]

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.

[Elipsit]

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 Lover]

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.

[mattthegamer463]

Wow, yes a lot of good points. The lead acid charging circuit would need to be changed, this one requires a 18V input voltage so charging from a car cigarette outlet wouldn't work. Definitely some neat ideas for somebody building a beefed up version of this. Thanks for the big post.

[Trike Lover]

Yes, I looked at your schematic and wasn't entirely sure why you'd gone for the 18 volt charger input. The SLA's will charge directly from a car cigarette lighter socket and don't seem to suffer any ill effects, based on my own experience.
The mini solar panel already has a charge controller built in, so no problem there.
Another option, if you _really_ want 18 volts at your charging circuit input and have only 13.8 VDC available, is to order a voltage "boost" board from EBay. These are essentially an upconverting switching power supply on a board, and will accept a variety of input voltages and give a set output voltage.

Anyhow, I'm trying to shoehorn a guittar amp, mixer, rechargeables, jacks, pots, etc. into a traveller's soap dish, to give a rechargeable portable headphone guitar practice amp. It's a tight fit.

Cheers & good luck.

P.S. I used four of those 1 watt solar panels to "top off" a 20 AH SLA battery, which in turn was running an electric cooler. They did a good job - I only had to resort to the "real" charger once in a while, I was surprised.

[mattthegamer463]

When you charge the 12V batteries directly from the cigarette lighter, can they be left indefinitely or do you need to make sure to unplug them after a certain amount of time?

Also, I bought that battery from a local store, brand new, for $15! Don't know why people keep telling me it is worth more than that. If it is, I guess I got a great deal.

[Trike Lover]

Your second point first - Yes, that is a great deal! I did some more checking around this morning and the lowest $ I found for that size of battery (new) was $27. So I sure wish I lived near your store, LOL!

Charging from the cigarette lighter, you can leave them plugged in. The regulator in the alternator will not charge the car battery to more than 13.8 volts, and thus your SLA battery, which is effectively in parallel, will also not exceed the 13.8 volts. As the battery voltage rises to the maximum value, the charging current decreases. There is some extra load on the alternator, but for a battery of this size it's minimal.

When I am manually charging one of these, I periodically check the SLA battery voltage with a meter and disconnect when they're at or above 13.6 volts. The one thing you don't want to do is have it in the circuit when you're starting the car - hard on the smaller battery.

I have a pair of 20 AH SLA batteries in the trunk of my car, to run ham radio equipment independently from the car battery. A simple isolator relay disconnects these from the car battery when the engine is not running. So, if the radios run the trunk batteries down, my car battery is unaffected. There are also solid-state battery isolators available, but I've found the relay works for my needs. I do have a remote voltmeter near the dash and the radio and antenna controls which shows the trunk battery voltage.

Been digging around my tickle trunk and found an ex-stereo speaker in a good box about the same size as yours, so I'm going to give this a try. Cheers.

[mattthegamer463]

Sounds like a good idea. I wanted to take good care of this battery ($15 is still a good chunk of money) and want it to last a long time, and read that a regulated charging current, and not greatly exceeding 12V will keep the battery optimal.

Good luck with your project.

[Trike Lover]

A short P.S. - the SLA battery in your photo costs, new, considerably more than $15, even from wholesalers or when on sale. Even if all other parts were on hand, the battery is quite costly if purchased new. Any suggestions as to an inexpensive source for cells of this size? Just curious.

[pecamuzicar]

Hi,

Ok, it is nice to think about music lover apps in retro style. But when you already like it (your pictures show how you was careful), it is not bad to say something about real basic (not audiophile :-) audio requirements there.

To put inside of factory optimized box: PCB (Printed circuit board) with amplifier, charger circuit etc. even heatsinks, is not big problem (for heatsink you can use your aluminum plate for switches, then to add some not fat heatsink externally to get better cooling - you saw how is made many active speakers). It will not take internal volume so much to change characteristic of speaker box factory coupled with bas-mid speaker driver for optimum response in low frequencies. But, this your big battery obviously will do.

To keep characteristic in lower frequencies, maybe you could to change i.e. already fat front side of box, with some few mm thick aluminum sheet, of course with care to not mess your new looking nice speaker box. So, when you will put inside your battery, internal box volume should to stay same approximately.

Second point: it is better to make a couple of smaller quality speaker boxes, just to get stereo sound image - also very basic thing. If their internal box volumes together will be equally with your a mono box, you will get also about equally response in lower frequencies.

Boxes of some very small retro bookshelf speakers was made from thin (~3mm) cast aluminum. Overall dimensions was 12x12x18cm, light weight. But still, sound was very satisfying. For bookshelf speakers is recommended to keep them near angles of room to get better low frequencies, so if you want to use them outside, keep them in front of some wall, rocks ...

I hope it was useful. :-)

Cheers

[mattthegamer463]

You're right about that, changing the internal volume by adding components can have a negative effect on the sound. However I don't notice any negative effect here. The bass response isn't phenomenal to begin with because after all these are small speakers, they never had booming bass to begin with.

[ChrisYarrow]

This looks great and I love that you're using components from tech that people would normally skip after they stop working.

I have some JBL 6x9 speaker that I've been meaning to reuse for some time now. This is just the inspiration I've been looking for.

Cheers pal!

[sshim1]

this is great but a video along with this would help better explain

[mattthegamer463]

Sorry I didn't make one, do you have any questions?

[sshim1]

also how did u set up the battery to charge while its till connected to the circuit board

[sshim1]

i new to this i can get the pieces together but the im new to the circuitry part and all the layouts really don't help im more of a see and do

[mattthegamer463]

Isn't really a lot to see with the circuitry but building from a schematic is pretty straightforward once you learn what all the symbols mean. What do you mean about how did I set up the battery to charge? The battery is connected to a charge circuit, and when the battery is charging the speakers play off the wall power. When SW1 is flipped from "charge" to "battery" mode it rewires the battery (+) from being connected to the charge terminal to the amplifier + voltage. Now the battery is powering the circuit.

[sshim1]

oh okay thanks that helped alot