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ipod pin 18 to power fiio?

post #1 of 5
12/15/08 at 9:39pm
Thread Starter 
according to pinouts pin 18 on an ipod is 3.3 v out. A fiio e3 runs on a aaa battery, 1,5v. Using a dock connector, potentiometer for volume,e3 and a voltage regulator, shouldnt you be able to make a ln amp that plugs into the ipod, uses linout and runs off the players battery?
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post #2 of 5
12/15/08 at 10:31pm
I was looking into something like this before but got stuck on the whole single supply voltage and tying signal ground to V- to feed to the amp.

http://www.head-fi.org/forums/f6/loo...ed-amp-253261/
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post #3 of 5
12/16/08 at 4:41am
Thread Starter 
Hmm... neither of the fiios existed back then. The E3 prob has some chip to upconvert 1.5v, the E3 has a rechargable battery - 3.7v 190mah i think. Considering the size of the E3, it would be the perfect candidate, although it doesnt have a volume control.
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post #4 of 5
12/16/08 at 6:19am
One of the larger difficulties I ran into was the fact that V- is attached to signal ground and this forces you to use input and output caps on the amp and it does not behave well with virtual ground (has a habit of collapsing it ).
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post #5 of 5
12/16/08 at 9:52am
Thread Starter 
Ah yes now i see what you mean. Not worth the touble then... Still would be nice to make a fiio e3 that clips onto the bottom of my touch and has a volume control, even if its still battery dependant. I ordered parts for that today, just need something to tinker with even if i plan on using a tiny LOD and an E5 for my touch.

One way to fix the problem (kinda) if you have an iphone is to get one of those cases that has a built in battery so the battery is on the back of the phone. It normally acts as a backup battery for the iphone, but if you disconnected that link and made it run an amp instead you would have two seperate battery sources, but the effectiveness of the space it takes VS how much battery power it gives would be tenfold that of a normal amp. The phone would be thicker, but at least streamlined
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