Kindle 3 DIY Light

The Kindle 3 uses a screen technology that looks almost like glossy magazine print.  What makes it remarkable and so easy to read is that it uses ambient light to illuminate the screen rather than a back light.  The quality of the image is fantastic in normal reading conditions, but gets difficult to read in low light situations.   
Amazon, in their great redesign of this product has thoughtfully included an in-built power source to run a light.  For a mere $60 Amazon provides a light-equipped leather cover that can tap into the power source.  
This Instructable will show you how to tap into the power source and build your own lighted cover.

Difficulty: Moderate

For some reason the photo notes feature broke half way through this instructable.  If something is unclear, please post a question and I will do my best to clarify.  Hopefully the feature will be unbroken in the future and I can add some more helpful notes.

(By the way, I haven't been here in a while and I'm disappointed to find that Instructables is trying to sell "PRO" formatting features to the people that actually GENERATE their content for FREE.  Lame.)

TOOLS:
* Google SketchUp (not needed, but helpful for viewing and manipulating plans)
* printer
* dremel tool with rotary cutting, routing, and grinding bits
* vice
* safety glasses
* ear protection
* assorted files
* scissors
* hobby knife 
* soldering iron
* drill and assorted bits
* multi-meter
* small clamps 
* coping saw

MATERIALS:
* 1.5 mm stainless steel sheet 
* 6.5 mm bass wood sheet
* 2.5 mm bass wood sheet
*160 x 230 x 23 mm hard cover book (W x L x H outside dimensions)
* heavy cardboard/plastic sheet
* braided elastic band
* glue stick
* gorilla glue
* 2.5mm screws
* 2x 3mm bright white LEDs
* 3x 1K ohm resistors
* 3x 220 ohm resistors
* stranded hookup wire
* proto board 
* SPST or DPDT micro switch (SPST for on/off) (SP Three Throw for low, off, high) RSOnline.co.uk Part 718-2317  or similar
* solder

Some Useful Information for other K3 Hackers:
Dimensions:
* Top power port 6mm wide x 8mm deep
* Bottom power port 5mm x 8mm
* Clips ~ .5mm thick
*~114 mm between ports

Electrical:
* Top port - +4V
* Bottom port - ground

Step 1 Create the Clips

The Amazon lighted cover uses two small brass clips to hold the K3 to the cover.  The kindle slides first onto the bottom clip at an angle and then a spring-loaded hook attaches to the top port.  My solution uses the elastic band in the upper right corner to secure the kindle instead of the spring-loaded clip.  
Check out the lighted cover instructions  from amazon for a better idea how the clips work.

1) Use the attached PDFs as a template to create the clips.  Print out each template and use a hobby knife to cut a template free.  Use a glue stick to attach the template to the 1.5 mm stainless steel plate.   NB! The PDFs are set for A4 paper and should print to the appropriate scale if A4 paper is chosen.

2) Cut the rough form using a cutting bit in a dremel tool.

3) Use the grinding tool to remove excess material and shape the clip.  It may be necessary to apply a new template if it becomes scorched or damaged.

4) Use a grinding bit to remove around .5 mm from each side of the portion that will attach to the kindle, leaving the rest of the clip intact.  To make this easier, I fastened the clip into a vice and only allowed the portion I wanted to grind to stick out. 

5) Check your dimensions against the diagrams below.

6) Test your clips by gently pushing them into the ports.  The lower clip should rotate upward as it slides into the port.  The clips should slide into the ports with very little resistance.  If it does not slide easily, grind the clip down and compare it to the printed templates.

7) Switch the kindle on and set your mulit-meter for DC voltage and check the voltage across the two clips.  It should be around 4V.  The top port should be positive and the bottom ground.  If there is no voltage across the clips, ensure the kindle is on.  When it is in sleep mode, the light will automatically turn off.  I also found that when my bottom clip was slightly too short, it did not properly make contact. 

8) Carefully drill 3mm holes in the clips.  A drill press and machine oil will help greatly in this process.

Comments

[qwerty156]

Sorry if i am being dumb but where is the power supply form the kindle?
I cant seem to find it?

[txoof]

The Kindle 3 has two tiny slots on the left side. Those two slots can be used to attach the reader to a cover like this one.  Inside of those tiny slots are electrical contacts that supply ~4V.  If you want to get an idea what you're shooting for, check out this (slightly obnoxious) video for a closer look at the guts.  I tore mine appart to measure the voltage and get a better idea of what the clips needed to touch.
If you follow the patterns I supplied, you should be able to grind out a clip that works fairly well.  I used stainless, but you could probably use brass stock as it is MUCH easier to work with.  I just couldn't lay my hands on any here in Norway.
Let me know if you have any other questions.

[qwerty156]

Oh wow thanks!
It works!
The 220 Ohm resistor would work for full brightness right?
thanks!

[txoof]

And, be sure to post some pictures of your finished product. I'd love to see what you finally end up with.

[txoof]

The brightness depends on the resistor. Greater resistance will give you a dimmer light. The minimum resistance depends on your particular LED. Check the data sheet. In general, around 200 OHMs is the minimum for a 3mm LED.

[qwerty156]

Yeah thanks!
I am using 5 3mm White leds in parallel.
Do you have anytips to make some sort of a diffuser?
Hot glue doesnt work that well!

[dquintans]

I'm a bit late to the party, but for future readers, ping-pong balls, pieces of styrofoam, and packing peanuts are excellent for diffusing. Just grind the front of the LED down smooth and flat to provide a wider viewing angle, then glue a ball of styrofoam down so that it covers the LED entirely.

[txoof]

If you can dig up a busted LCD screen, there are some great diffuser layers between the CCFL and the liquid crystal.