Portable stereo amplifier?

[scwhiteley]

My name is Chad, and my success regarding electronics projects could be accurately described as: hit & miss.

That being said, here's what I'm trying to do:

I have a pair of 4-ohm car speakers, I have an iPod, and I'd like to use them to make a portable back-pack stereo (boom-bag). I'm hoping to use a bunch of D-cell batteries to power this thing, or perhaps I can get a hold of some lithium battery that will do the trick.

My problem is this:

Clearly one cannot just run a pair of car speakers using the output from an iPod, so I need an amplifier. I've not been able to find exactly what I need in the far reaches of the internet, so I may have to build one. But how? What kind of amplifier do I need? It needs to be small and efficient, able to run on D-cell batteries but able to power a pair of 4-ohm speakers. Am I asking too much? Is this even possible? I hope so.

I've made a few electronics projects in my day, some of them have even worked. I've got the equipment and the know-how to solder and wire and put stuff together, I just don't have the background or understanding of amplifier circuits to do this thing on my own. If anyone could help, that would be great. Even if someone could just suggest a good reference book that would set me in the right direction, that would be a huge step forward.

Thanks a lot!

S. Chad Whiteley

 

[Audioguru]

Years ago there were amplifier ICs that could operate from a 7.2V battery and produce 5W into 4 ohms when bridged but they are discontinued.

There are still a couple of amplifiers that use a 6V to 9V power supply and have an output of only half a Watt into 8 ohms. They cannot drive 4 ohms efficiently.

There are hundreds of bridged car radio amplifiers with 14W and more into 4 ohms. They need at least 13.2V which is a big battery.

You might be able to make a boosted amplifier from an LM386 half-watt amplifier and two power transistors. Then bridge two of these.

 

[ctownsend]

I did the same thing using two inexpensive ($15) computer speakers. They have a small stereo amplifier built in. Just plugged the MP3 player in.

I did not run it off batteries. I am not sure how long the batteries will last.

Maybe you can use rechargeables with a small solar panel??

 

[Audioguru]

Maybe you can use rechargeables with a small solar panel??

A small solar panel is in a solar garden light. It provides a very small amount of power to charge a little battery so it can dimly light one LED for a couple of hours after charging all day. A portable stereo needs a lot more power than a dim garden light. Maybe a huge solar panel (expensive) might work.

 

[finhas786]

just use a comp speakers and use a li ion batt