• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Turning computer speakers into portable mp3 amplifier. Problem.

Not open for further replies.


New Member
I'm trying to make a portable mp3 amplifier out of two computer speakers. Now I have read this article on how to make them:
Also, here's a picture of my amplifier, battery pack and speaker: http://imageshack.us/g/163/img2012t.jpg/
I'm stuck at step 3 where you should add the power source (in my case a compatible battery pack). I have the battery pack and want to either solder it directly onto the board or connect them with the two wires that I cut from the power transformer. Where do I solder the two wired to the board or which two wires from the battery pack should I connect to the two wires from the old transformer? In other words, how do I connect the battery pack to the amplifier?
I know, the explanation wasn't the best but I would be really glad if you tried helping since I have had this problem for a long time now already...


Well-Known Member
Most Helpful Member
Most Instructables are designed by kids who know NOTHING about electronics.
This kid shows a 9V transformer and guesses wrongly that a 9V battery is the same. WRONG!

The 9VAC transformer has a peak voltage of 12.7V and when rectified and filtered produces 11.3VDC, not 9VDC from a little battery that drops to 6VDC during its life.

If you connect your 6V battery (it will be 4V when it gets old) to where the transformer connected then the full wave rectifier will reduce the voltage to only 4.6VDC with a new battery and only 2.6VDC when the battery is old. Will your computer speaker amplifier work from your battery that is only 2.6V to 4.6V?
Not open for further replies.

Latest threads

EE World Online Articles