Dane.Kouttron
Quick Power Supply for a Macbook G4
This
is also
useful if your stuck in the congo, and need to power a macbook g4 off
of 2 jeep batteries and hack apart a mini cell phone ear piece for
power. Jack Bauer approved.
| What? |
Build & Test | Conclusion | Image Directory |
| Component | Purpose | Image |
| Simple 3/32nd in audio jack | About
the same
size as an apple legit power jack internal plug only moderately over priced at your local radio shack Probably the most ridiculous use for the 3/32nd size, 2A over a mini headphone size cable, If apple ever goes into power engineering i'm leaving. |
 |
| Here is another image of the connector, next to a small battery for scale |  |
|
| Multmeters | ammeter / voltmeters are very useful, but not necessary | |
| Crufty Power Supply | 24v,
~2A power supply. i found this
crufting years ago, it was for a childs scooter, probably a charger.
After scoping the outputs, i found that with the addition of 100uf of
output capacitance it was clean enough for me to try it out on the
macbook. As the current output is less than optimal, i let the macbook
charge before attempting to boot. if the macbook attempted to charge
quickly while booting it would possibly brown out the power supply. Even if you only have a 24V 1A supply, use it to charge the laptop batts, (leave it pluged in with the laptop off), you could boot from the internal batts later on If youve got access to a varable power supply that can do 2 A use it (like this one) |
 |
Build &Test:
| Action | Purpose | Image |
| Solder | solder wires as shown. check for high impedance state between wires before applying power (there shouldnt be any resistance at all between the two wires, if there is (and its a low value) youve got a solder bridge. fix it. |  |
| Test | before booting the machine, have an ammeter in series with the supply, check the amperage consumed. ~1 A (while the mac is off, but charging) is appropriate. if its pulling far more than this, something is wrong. if you dont have an interna battery, but its not pulling crazy amounts of current, attempt a boot. |  |
| Here
is an image of
the adapter plugged into the G4 macbook, (Black USB drive has Ubuntu Kernel on it, for loading legitimate OS) |
 |
| Hurray
it works! Macbook running from 2 lead acid gel cells, thru an ammeter and a fuse. Macbook Battery also charges! fuse was necessary to prevent large amounts of damage if incorrectly wired. macbook consumes 1.2A at 24V (while not charging internal battery) and upwards of 2.2 A while charging internal lithium cell |
 |
References:
http://pinouts.ru/Power/apple_tibookpower_pinout.shtml
People who worked on this project:
| Dane
Kouttron (EE/ soldering / OS stuff) |
Emily
Krupczak Found the mac, helped out alligator-clipping / finding screws / generating ideas |
Special Thanks:
MITERS
Dane.Kouttron
Rensselaer Polytechnic Institute
Electrical & Electrical Power
631.978.1650
