Do you like the quality of computer speakers and wish you could take them camping but never could because they run on 250V. Or do you just have a pair of old speekers lying around and looking for somthing to do with them. Then this instructable is for you!
In this instructable I will give you step by step instructions on converting a pair of genius speakers to run off two 9V batterys.
For a couple of months I have ben working on trying to perfect a lm386 amp but gave up after I contuied getting bad static quality. I picked up a pair of geinus speekers wich I liked the quality of. And I then thought that they would never possiably need 240V to run so I opend them up and found out that they had a 240V to 9V step down transfourmer so I set to work converting them to run off 9 volt batterys.
Step 1: Parts & Tools.
Tip cleaning sponge.
Wire stripper (not showen in picture).
Soldering iron gas (if you have a gas soldering iron).
2 X 9 volt battery snaps.
2 X 9 volt battery.
Genius speakers (SP-K06).
Step 2: Remove Front Plate.
Using a lardge knife slide the knife in between the plastic and fabric. Gentley work your way around the speeker box (olny the main one) levering off the front plate, take care not to stab the speaker.
Step 3: Open Up.
Remove all screws, there is four of them two on the front and two on the back.
Step 4: Working Out How Much Current You Need.
I thought that somthing of the size of my speekers wouldn't need 240V to run, inside found a stepdown transfourmer stating that it provided 9V at 0.3A. I did some research and found that most 9V batterys supply 200/300ma meaning that I would need two batterys in paralell to make it run if the batterys supplyed 200ma each.
Step 5: AC to DC?
AC current stands for alternating current witch means that the power changes from positave to negitave and then back to positave and the other wire being ground.
DC stands for direct current and means that one wire is always positave and the other is always negitaive or grond
AC is not as usefull as DC but things like transfourmers cannot run off DC and it is easyer to convert AC to DC so mains power (the power that is supplyed from wall plugs) supplys AC.
AC wich is a problem for us becausThe transfourmer supplys e batterys olny supply DC, and DC it is harder to convert into AC.
Luckley the circuit that was in my speeker had four diodes aranged as a bridge rectifyer. A bridge rectifyers purpose is to convert AC to DC witch is what our batterys supply. This means that what looks like our board draws AC the board its self actually converts it into DC before it reaches anything so we can connect our batterys directley to the input.
Step 6: Preparing the Battery Connecters.
Strip about 1cm of the ends of your battery connecters and twist all he positaive and all the negitaive leads together (posative to positaive and negitaive to negitaive).
Step 7: Cut the Wire!
Cut the two wires that run out of the transfourmer and into the amp leaving enough wire from the board to strip and solder on to. Then strip about 1cm from the ends of the cables that run to the amp. Twist these cables onto the battery connectors. Polarity does not matter because of thee recifyer. Then solder these cables together. Wrap all exposed wires in tape and tape to the side of the case too stop rattling.
I did not have any photos of soldering because my iron blocked up. I will be adding pics when I can solder again.
Step 8: Remove Transfourmer and Power Cables.
This step is optional. I planned on adding a dpdt switch to toggle between batterys and wall plug later so I left it in.
Un-screw the transfourmer from the casing then using a pair of plyers squeeze the clip that holds the cable in and then pull out. Cut the power plug off and pull the cable through. You can throw out the transfourmer, keep it for use in other things or convert the speekers back later.
Step 9: Finish! Add Batteys, Reassemble and Test.
Add the batterys and test. I wrapped the batterys in tape to stop them shorting on anything. Put the batterys inside the casing and tape down to stop them bashing around and breaking anything. Re-assemble the speekers the same way you pulled them apart.
Done. Thanks for reading my instructable. I will be uploading more soonish like How To Make A Grass-Kart (go kart).