[andyreynold]

Hey folks.

I recently discovered two things about my FiiO amp.

1. It makes my KOSS SB45's sound better with certain music
2. It eats AAA's very quickly

I was hoping to remedy the second item on that list by powering it from a USB power source. I know that USB outputs about 5V, and that my FiiO requires 1.5V. I'm not sure what component(s) I should be looking for.. a resistor, maybe a voltage regulator? Please let me know if you have a better idea of how to build a circuit that can output 1.5V from 5V. Also, if it can be done, an on and off switch would be a nice addition.

Thanks for your time and cheers!

 

[brandnewgame]

Wait for an E5 with li-ion battery or switch between two rechargeable triple As? Just trying to save you hassle

 

[andyreynold]

Quote:

Originally Posted by brandnewgame /img/forum/go_quote.gif Wait for an E5 with li-ion battery or switch between two rechargeable triple As? Just trying to save you hassle

Those are both good ideas.. but considering how often I use the headphones, I would probably end up recharging/switching AAA's almost every day.

Thanks for the reply though!

 

[elliot42]

What you need to use is the trusty LM317 voltage regulator, that will get the 5V down to 1.5 with the right configuration. It might be a tight squeeze, unless you can find the chip in a package smaller than the regular TO220.

 

[diredesire]

Quote:

Originally Posted by elliot42 /img/forum/go_quote.gif What you need to use is the trusty LM317 voltage regulator, that will get the 5V down to 1.5 with the right configuration. It might be a tight squeeze, unless you can find the chip in a package smaller than the regular TO220.

That would have been my suggestion. LM317s also come in TO-92, but the current they can sink is smaller (IIRC 350mA vs TO220 1.5A).

You need to see how much current the device takes to see if it will be possible on the USB bus, first. I am certainly guessing it can be done, though.

 

[mape00]

I think it would be a good idea to build a fake AAA battery connected to a usb port using the LM317 since the battery is loaded sideways in the FiiO.

 

[alamakazam]

I tap direct with 5v USB to FiiO and it works!! well is overheating\

 

[geob]

Quote:

Originally Posted by brandnewgame /img/forum/go_quote.gif Wait for an E5 with li-ion battery or switch between two rechargeable triple As? Just trying to save you hassle

Get yourself some 850 mAH Ni-MH rechargeable's and a USB based charger. You will only need to change batteries once every 20 hours or so.

 

[Moontan13]

Quote:

Originally Posted by andyreynold /img/forum/go_quote.gif Those are both good ideas.. but considering how often I use the headphones, I would probably end up recharging/switching AAA's almost every day.

NiMHs can also drop below acceptable voltage pretty quick. I had to find AAA cells with a lower MAH rating to get around 8 hours of run time.

 

[Captain ?degard]

My frankenfiio (now v2) runs off two AA's: http://www.head-fi.org/forums/f5/qui...17/index2.html

that might be an idea for you - itll make the thing bigger but still. if you do 4 parallell connected AA batteries plus the AAA in the fiio in a configuration that makes the fiio longer but not wider or thicker, itll still fit behind a player well (if thats where you use it) and the battery life will be 15 times as long