Homemade Nexus S Dock with resistor trigger

After a bit of searching I made a dock for my Nexus S and thought I'd show the results here.

I found out about polymer clay in this post (the thanks button is disabled for some reason...).

And I used the resistor values listed here, as some other threads showed they also worked with the Nexus S: Fun with resistors (home/car dock mode + more)

I ordered a Sparkfun microUSB breakout board, bought some resistors at a local electronics shop and four blocks of black Fimo clay at a nearby arts shop. I had the other supplies on hand:

-Soldering iron, solder, etc.
-Shrink wrap in various sizes.
-Hot glue.
-Aluminium plate.
-USB cable.
-Narrow and slightly rounded file.
-Box cutter or exacto knife.

I made the cable first (and did not take pictures at that time) and ensured that part worked before tackling the clay portion of the project.

I soldered one end of the resistor on the breakout board and the other directly on a stripped portion of the ground cable. The data wires remain functional as I am using a wall charger that properly shorts the D+ and D- wires to enable AC mode. I secured everything to the board with hot glue and finished off with shrink wrap.

This was my first time working with Fimo and it went well. I wrapped my phone in cellophane for a test fit along with the modified cable. The cable however isn't rated for the baking temperature so this was only temporary.

After baking, it turned out that I had misplaced the portion meant to hold the cable, so I snapped it off and made another with some left-over clay. The cured material can handle rebaking with no issues.

A bit of rework on the attachment point with a knife, test fit again, glue the board and file a notch for the buttons.

The phone slides in and out smoothly. I'm quite satisfied with the results.

Update: dock still works great. I've made one mod though: I took an old mouse pad, tore off the cloth on the top, cut a shape matching the dock's bottom, and hot glued the two together. This anti-skid pad means I can turn off the alarm or answer a call (which the phone answers in speakerphone mode right away) without inadvertently moving my phone on the nightstand.

Goodbye,

Darkshado

Thanks for the feedback!

daudster: sorry, but its too late for a video. The good news is that there are plenty of good soldering tutorials out there.

This post by Fallon also has nice pictures that are very close to what I've done myself.

I started with the cable.
My "donor" USB cable was a standard compliant color coded affair. (Red Vcc, Black Ground, Green D+, White D-)
Checking with a multimeter to be safe is a very good idea.
Given the gauge of your typical USB cable wires and the breakout board's holes I suggest you presolder your wires.
Holding the stripped end of your wires with a sufficiently massive pair of pliers will make a nice heat sink to prevent melting the insulation when soldering.

Instead of doing like Fallon and placing the resistor above the breakout board, I soldered one pin on the board, the other on a stripped section of the ground cable "downhill" from the board. If you want to do it like this, make sure that you don't short your resistor with the ground cable. Then cover with shrink wrap.

Lousy ASCII art diagram below:
(Breakout board on the left)
ID--------R------\
GND--======---====

Depending on your exact design, this may not be necessary, but I opted to secure the small gauge wires to the board with hot glue, prior to covering with a larger diameter length of shrink wrap. While this cable's solidity might not be commercial grade, tugging on the cable by mistake would not risk as much damage.

Also a departure from Fallon's post is that I am using a Samsung OEM wall charger that shorts the Data wires in the charger itself, enabling AC mode, so no need to do it on the breakout board. My cable is confirmed working on the computer with both ADB and USB Mass Storage file transfer.

Test as you go to make sure none of your solders introduced unwanted short-circuits. (Fail to do this is and you could very well KILL your precious Nexus S or computer.)

Now, the Fimo part.

This was my first time ever working with Fimo and it turned out to be easy. As you work the material you heat it a little (friction) and it becomes a bit tacky to the touch so I worked on a small sheet of aluminium foil, wax paper might be better yet.

The aluminium plate is used for curing, as its much easier to handle with oven mitts and solid enough for this purpose.

Roll three blocks of Fimo in a sheet about 6-8 mm (¼") thick. With a blade, cut the excess on each side to end up with a properly sized rectangle for the back and bottom of the dock. These leftover bits will serve to support the back as well as the breakout board.

I kept my back flat, you may want to have it curved like the Samsung OEM one. Your choice, I chose flat because its easier to make and to simplify reuse with minimal modification when I'll change phones down the road.

The notch in the bottom for the buttons may be done before or after curing. Before, your fingers, a pen, coffee stirrer sticks or popsicle sticks all work. After, a rounded file or sandpaper.

My first breakout board support was misaligned so I had to break it off. For this reason I suggest you consider doing it in a second curing. This way your test fits are going to be much more accurate.

Most cables aren't rated for high enough temperatures to follow the Fimo in the oven for its curing. That's what lead me to making a support with a notch and using hot glue to finish the job. It's also flexible enough in case your alignment isn't perfect.

Goodbye,

Darkshado