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Answers : Technology

SFX 5.4 Louspeaker connected to Galaxy S/Arduino?

Hi All,

My brother kindly gave me a bag of electrical stuff that were being tossed from his office. Included is a SFX 5.4 Louspeaker (pics below). It has two screw terminals, and I was wondering if it would be possible to connect this to my Galaxy S phone. I have a length of headphone cable.
I've stripped off the headphones, and exposed the wires, however I'm a little confused as theres more wire than I was expecting. The other end of the cable terminates in a 3.5mm jack.
Anyone have any ideas on how to connect this up?
I'd also like to interface this with arduino, but getting it to work with my phone is first!

Thanks
Jason

2 answers	Answer it!

Jun 23, 2011. 9:25 AM

andy70707 says:

It is probably a multi-purpose cable that combines a microphone or control wire too. A standard 3.5" stereo cable should have 3 wires (ground, left and right) and a 3.5" mono cable should just have the two. I would test them with a multimeter as it is unclear what they are from the picture. The red is probably left, and one of the darker colours is probably ground. You will need to use a lighter or soldering iron on the ends of the wires before testing to melt the enamel off as they are coated in is so they can be bundled together in the cable. Then, you just connect up the ground and left speaker wire to the loudspeaker. Remember, it will still be pretty quiet as it doesn't look like the speaker has an amplifier. You can make one yourself with a LM368 and a few resistors and capacitors. Search LM386 schematic on google and you will find several low-power audio amps suitable for your application.

Jun 23, 2011. 11:10 AMinbox.jason (author) says:

Thanks for your reply, Andy70707! I've got a LM286 lying around, but no caps so till I order some in this has stalled. You've set me on the right path!
Thanks again!