Word of caution: If I were you, i would not use these with mp3 players that use hard disk drives (as opposed to flash memory, like many newer ones) because there is a chance that the magnets in the speakers could mess up the data on the disk, and brick your player.
So i built this, not knowing how well it would work, and when I finished, I realized that I should have taken photos so I could make an instructable about it. So I have whipped out my trusty tablet, and recreated all the steps by drawing them out in painter 6. If anything is confusing, please tell me so i can clarify.
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Signing UpStep 1Materials
8mm male audio jack
Sheet aluminum. I just used aluminum flashing, which is extremely thin, and can be cut with scissors
Aluminum tape
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Decent audio equipment may have protection against this, but all I was told during my digital electronics classes was "don't connect outputs together, if they output different voltages then current will flow between them", hence the existence of tri-state logic.
(amps ( or ma) x V = watts)
so lets say your ipod battery is 3.7 V (it would be as it is a single cell lipo battery)
100ma = 0.1 A
3.7 x 0.1 = 0.37
lets say 0.4 W
a set of ear phones are about 0.05 W
thats 8 times the power of a set of earphones.
As for speakers only pulling as much power as is available , its sorta the other way round , there is no limiting on the ipod. it would be nion impossible to implement limiting , without the ipod knowing what sound output device it was connected to , earphones only pull 0.05 W , so no limiting is needed , headphones however , given half a chance will pull into the amps , thats why if you crack open a set of headphones you will find a resistor somewhere in the circuit , they are normally buried somewhere in the jack.
if you need any help pm me : )
Now i have a friends who is a complete audiophile, he has some extremely expensive earphones which are all cast acrylic, you can see right through them. On the protion of the lead where it splits into 2 to go to the L and R earbuds, there is a clearly labelled SMD diode and 2 resistors on a tiny little pcb.I found some 1 quid earphones in the pound shop , bought them and just out of sheer curiosity ripped them apart, no internal resistor anywhere ? So i put a multi meter on the leads and i was a massive 0 ohms , compared with 25 oms to my half decent earphones. I dont know this for sure but i would guess that this sit eh cause of their crappy quality and cheapness. so whack a multimeter on the terminals of the little speaker if you can and then again on the 3.5 mm jack to see if it does have an internal resistor or not, i know for a fact my half decent earphones do have a internal resistor ( that r the wire going to them has a resistance of 60 something ohms :P). Wouldnt say a resistor is the sign of quality, but aslong as its high enouhg to stop the ipods mosfets going into thermal runaway then it this should be ok. ill explain the parts with te speakers in a minute, my fingers hurt.
Speakers are designed to be a lot louder and move a lot more, therefore they will have thicker wire for their electromagnets and less of it , I have just measured a speaker similar to the one techno chicken sued at 4.5 ohms, no where enar as much resistance as a pair of earphones this will allow a lot lot lot more electricity (specifically milliamps) though eh speakers and through eh sound cards mosfets they might be ok now but i assure you those little pin head sized dots of silicon that are the mosfets for the sound amp are getting very very hot and slowly dying. I produce speed controllers for combat robots so i know a fair bit about how mosfets tick, and i tell you thaqt they can stand quite a bit of abuse until one day, they just die, you could run them over there limit for hours and they will eb fine , but suddenly with no warning they die and that's a new ipod motherboard at least. completely disregarding all of this, they will sound awfull, bass will be non existant and it will always sound tinny however much you fiddle with the EQ. And i hate ipods and everything about mac, and all my friends are mac fan boys, i feel your pain xana. so yeh , need any helpz repy and ill give you my email or msn or something.