The whole point of this DIY:

There are plenty of cables and adaptors that you can purchase (or build using other DIY instructions) that will allow you to attach a modified MagSafe connector to a Kensington universal laptop power supply. I didn't like any of those solutions -- why?? Well, frankly, they were ugly and not elegant. Why would you start with your beautiful aluminum MacBook Pro and equally beautiful Kensington AC/DC adaptor -- then attach a hideous collection of adaptors, connectors, cables and excess parts?? Just to use a third-party AC/DC adaptor? Well, not this Mac user...

Below you will find a description of how I modified my Kensington and MagSafe cable to create a very simple and significantly more elegant solution to your AC and DC power needs. It is not intended to encourage you to do this on your own and I will not accept responsibility for any mistakes you make and any equipment you fry. But honestly, it is a surprisingly simple project if you have some basic requisite skills:

    * Basic electronics understanding

    * Basic soldering skills

If you choose to undertake a similar project, please read the entire instructions before you start. Make sure you understand why the instructions tell you to do something -- every instruction is there for a specific reason. Lastly, I repeat: I will not take responsibility for anything you fry, damage or blow up even if you follow these instructions exactly.

Here is a list of supplies that you will need:

    * Digital Multimeter (test outputs BEFORE connecting to your beloved Mac!)

    * Kensington 70, 85 or 120 watt AC, DC or AC/DC adaptor

    * Apple MagSafe cable (purchase one from eBay -- don't mangle your primary AC adapter)

    * Resistor 2.2 K Ohms (red to white)

    * Resistor 1.5 K Ohms (white to blue)

    * 1/8" heat shrink tubing

    * 3/8" heat shrink tubing

    * 1/2" Marine-grade adhesive lined heat shrink tubing

    * Soldering iron

    * Electronics-grade Solder

    * Electronics-grade Flux

    * Hot Air Gun (or other source of heat for tubing)

Step One: Cut and prep your Kensington Cable

After you cut the Kensington cable in half, strip the outer insulation back about 2 inches. You will see an outer shielding braid that is also the ground conductor. Inside the braid, you will find a larger gauge yellow wire (positive) and 3 smaller gauge wires -- red, white and blue -- used for voltage selection. Cut the wires to length as shown in the photo -- the outer braid should be full length. Cut the yellow wire about 3/8" shorter and strip the end. Cut the blue, white and red wires progressively shorter and strip the ends. Save the other end -- or better yet, make another cable and give it to a friend!

Step Two: Tin all the wires and attach the first resistor

Start this step by tinning all the ends of the wires you just clipped. Clip the leads on the resistors so they are fairly short -- approx 1/4" from the resistor body. Tin those ends as well. Solder the first resistor to the end of the red wire.

Step Three: Cover your first solder joint

Cut a short length of the 1/8" heat shrink tubing (approx 1/2" long) and slip over the resistor body and apply heat gradually. Allow the tubing to shrink tight over the resistor body and exposed end of the red wire.

Step Four: Attach the second resistor

Solder the two resistors together and attach the white wire to this same joint.

Step Five: Cover your second solder joint

Cut a short length of the 1/8" heat shrink tubing (approx 1/2" long) and slip over the second resistor body and apply heat gradually. Allow the tubing to shrink tight over the resistor body and be sure the tubing is long enough to cover the ends of both resistors and the exposed end of the white wire.

Step Six: Attach the blue wire and cover

Solder the blue wire to the end of the second resistor. Cut a short length of the 1/8" heat shrink tubing (approx 3/8" long) and slip over the end of second resistor body and apply heat gradually. Allow the tubing to shrink tight over the resistor body and be sure the tubing is long enough to cover the end of the second resistor and the exposed end of the blue wire. Note: It is a cleaner assembly if the blue wire and second resistor enter the same side of the tubing -- nothing comes out the end of the tubing.

Step Seven: Last bit of prep of the Kensington cable

Tin both ends with solder. Cut a length of 1/8" heat shrink tubing long enough to cover most of the twisted braid, with approx 1/4" exposed. Note: Make sure the twisted braid is SHORTER than the yellow wire, below the point where the yellow wire is stripped. This will help ensure there is no short circuit. Cut a short piece (approx 1/4") of marine grade heat shrink tubing and place over the cut end of the outer insulation and apply heat. This tubing is filled with glue that melts when heated and bonds to the cable insulation and the loose wires in the outer braid. This helps keep everything in place and prevents the braid from unravelling.

Break & Test One

Take a short break and inspect your work. If you're happy with your solder joints and are positive there are no short circuits, go ahead and connect your cable to your Kensington AC/DC adaptor. Set your Digital Multi-meter to test for DC voltage and then connect the black and yellow leads -- using alligator clips so you don't have to hold on. CAREFULLY plug in your Kensington adaptor to AC power and measure the output voltage. Unplug the Kensington adaptor from AC power. If you are happy with the output voltage, continue...

Step Eight: Prep the MagSafe cable

Cut the AC adaptor end off the Apple MagSafe cable. Note: You can make this cable as long or as short as you like. I used the maximum length of the white Apple cable -- this cable is very thin and flexible. I prefer this over the thicker black Kensington cable, so I kept as much of the white cable as possible.

Step Nine: More prep of the MagSafe cable

Strip the cut end of the Apple cable -- much like the Kensington cable, you'll find a sheild braid that is the negative conductor and only a single conductor (positive). Cut the center conductor slightly shorter, strip the end of the center conductor and twist the ends together as shown.

Step Ten: Last bit of prep of the MagSafe cable

Tin both ends with solder. Cut a length of 1/8" heat shrink tubing long enough to cover the twisted braid section past the end of the center conductor. Note: The heat shrink tubing covers the braid PAST the end of the center conductor to help prevent short circuits. This is important!! Cut a short piece (approx 1/4") of marine grade heat shrink tubing and place over the cut end of the outer insulation and apply heat. This tubing is filled with glue that melts when heated and bonds to the cable insulation and the loose wires in the outer braid. This helps keep everything in place and prevents the braid from unravelling.

Break & Over Cover Tubing

Take a short break and inspect your work. If you're happy with your solder joints and are positive there are no short circuits, pat yourself on the back and wipe your brow. BEFORE you continue: Cut a length of 1/2" marine-grade heat shrink tubing that is long enough to cover THE ENTIRE joint -- past the two short marine-grade bands. Those two marine-grade bands around the insulation ends will help secure the Over Cover into the proper position. Slide the Over Cover piece down the white Apple cable. You MUST do this step BEFORE proceeding!

Step Eleven: Join the two center conductors

Note: BEFORE soldering the two wires together, cut a short piece of 1/8" heat shrink tubing and slide down the yellow conductor -- as far down as possible. Solder the yellow Kensington wire to the white Apple wire. Try to do this with a minimum of heating to help ensure the heat shrink tubing doesn't shrink prematurely. Slide the tubing over the exposed solder joint. Apply heat and shrink the tube! Particularly since this this is the primary source of high amperage in this system, it is CRITICAL to ensure there is no exposed conductor in this particular joint.

Step Twelve: Join the two ground conductors

Note: BEFORE soldering the two wires together, cut a short piece of 1/8" heat shrink tubing and slide down one of the twisted ground conductors -- as far down as possible. Solder the two ground/braid conductors together. Try to do this with a minimum of heating to help ensure the heat shrink tubing doesn't shrink prematurely. Slide the tubing over the exposed solder joint. Apply heat and shrink the tube!

Break & Test Two

IMPORTANT: Make sure the cable is working as you want BEFORE moving past this step. Take a short break and inspect your work. If you're happy with your solder joints and are positive there are no short circuits, go ahead and connect your cable to your Kensington AC/DC adaptor. Set your Digital Multi-meter to test for DC voltage. CAREFULLY plug in your Kensington adaptor to AC power and measure the output voltage. Unplug the Kensington adaptor from AC power. If you are happy with the output voltage, connect to your MacBook and make sure it works...

Final Step: Position and shrink the Over Cover

Note: Because this final Over Cover tubing has an adhesive liner, don't rush this step. When you are happy everything is working as desired and to the quality standards you are willing to live with, slide the Over Cover tubing into position and apply heat. Be sure the adhesive is heated enough to melt and press into place -- starting at the center and moving outward -- to remove any air bubbles.

You're Done!

You now have an elegant (not to mention long) cable that doesn't have all that junk you would otherwise have to live with. It won't fall apart like other solutions and works great!

July 2009 Update

As you can see in the top photo, I have made another cable using the MacBook Air MagSafe cable (with a right-angle plug). When used with the white Kensington AC/DC Power Adapter, it looks practically like a genuine Apple solution!

I substituted the final over-wrap tubing with white shrink tubing -- locks much nicer! See the first photo on this page.

2009 MBP 17” likes the 70 watt adapter just fine. It has been working great. If the battery is COMPLETELY depleted, the 70 watt adapter will not provide enough power to boot the MBP. But, after 10-15 minutes of charging, everything returns to normal...

(c) Copyright 2008 - 2009, Erik Moon, All rights reserved.