http://www.headphoneamp.co.kr/ftp/sijosae/Gallery/ - view Sijosae's Designs
Originally I was assmebling Radio Shack pre-made battery packs (2xAA or 4xAA) in Altoid tins with USB (5V) connectors. However these AA cells were large & required both frequent battery changes, low voltages, required cables and had poor charge times for a dead iPod...problems.
See Ted's excellent reviews: http://home.speedfactory.net/tcashin/ipodbattery.htm
Firewire has better potential, smaller packages and requires no cables. Newer iPods only...
Using rechargeable NiMh 9 volt batteries provide higher voltages for use with firewire than AA's, although most have only 700mAh while the AA batteries can be obtained up to 1200-2700mAh. However AA Packs of 6 or 8 can be awkward, heavy and hard to manage easily. Alkaline 9v's can be had online or at discounts as low as 55 to 99 cents ea.!
So we use 9v in series or parallel with firewire!
comments on AA vs. 9v batteries? Rechargeables vs. Alkaline dry cells
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Working on small Cmoy amps I found many small designs online I liked. The Duracell was perfect for a single 9V solution. An Altoid tin will easily house Dual 9v (serial or parallel) and provide power similiar to the Apple AC adapter and the IEE1394 firewire output from a desktop or laptop.
Having used USB powered at 5 volts this promised to provide better performance for both old and "new" iPod's.
Firewire specs: http://www.1394ta.org/Technology/Specifications/









































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http://www.apple.com/pr/library/2004/oct/26u2ipod.html
Smaller units only require 5v at 500mA via USB for charging.
Check your make/model. Some will change some not.
All iPods are voltage/current sensing as are the wll warts and plugs.
But always test and use proper grounding or voltage/current protection!
Using solid state voltage regulators or LDO's will step up Voltage and drop current or step down voltage etc.
All the extra voltage or current MUST go somewhere. A complex regulated circuit is possible that allows proper mA and V+ to ipod and also allows monitoring of battery life or rechage for NiMH or LiPo sources but is more expensive and complex....
but it didn't charge...help please?!
Here are the pin outs...you must connect the numbered pins.
http://ipodlinux.org/Dock_Connector
you need to find which wire is the USB V+ and which is GND
and then the Firewire V+ and GND
then connect the commond GND to all th other GND.
This will VARY BY CABLE. So test pins for dock end and find the cable that matchs pins on the dock connector. then solder those to a 9v snap connector
Pin#/Functions
Note: These pins were previously listed in reverse order.
1FireWire Ground 1
2 FireWire Ground 1
FireWire Data TPB (+)
USB Data (+) 2
FireWire Data TPB (−)
USB Data (−) 2
FireWire Data TPA (+)
8 USB VBUS Power +5 VDC (from computer) 2
FireWire Data TPA (−)
Accessory Indicator 3
11 Firewire Power +12 VDC 4
12 Firewire Power +12 VDC 4
+3.3V Power (to power iPod accessories) 5
15 USB GND 6
16 Ground 6
Serial RxD
Serial TxD
Serial GND
S-Video Luminance 7, Component Pr
S-Video Chrominance 7, Component Y
Video Out - Composite Video (for ipod colour when slideshow activated)8, Component Pb
Line In - Left
Line In - Right
Line Out - Left
Line Out - Right
Line Out - Common Ground
30 Ground
Even large Research or academic (lasers, masers or rail-run etst) use 12v lead acid or dry cell in series or parallel combos with massive capacitors to get many amps/Joules of power for testing ...the dry cells have large resistance and impedance whereas capacitors can "dump" and provide that megavolt and multi joules "kick"...
E
Lithium based battery chemistries are pretty dangerous when your making/using non-comercial chargers, as in, buy them in a case from large comercial brands if your not too sure, or get someone who knows. Best buy lithium batteries with the charger, that way your generally garenteed to get the right stuff.
I know in the UK you can get 3000mAh Energizer rechargables. I've got about 8 or so and I use the engergiser recharger which holds four, so I cycle between to give me 6v for electronics prototyping.
The mini 12v batteries are pants. They have an absolutely minimum mAh rating.
mAh is how long the battery will last acording to the amps drawn. e.g. my 3000mAh batteries will last for 10 hours if I only need 300mA from them, should I need 3A (3000mA = 3A) then they'll only last an hour and so on.
can you please help me?