Keyboard

This page is about my keyboard mod project, Which has been featured on hack-a-day.com!

It’s taken me a few months of hard work to figure out, modify, solder and construct this bad boy. This project started when I decided that I was over Bluetooth keyboards, and went back to my trusty ol Microsoft natural keyboard. After a few months the sheer size of the thing was severely annoying me. When I went looking for a split key without the number pad, sadly I found nothing. So I decided to build something! After some searching I found this apple keyboard that could split down the center and angle out at about 30 degrees. Although it was almost perfect, I decided that I couldn’t simply mod it. After all, it’s a Mac keyboard... So I decided to use a Microsoft comfort curve keyboard 2000 for the control board donor.

After a few weeks of ON and OFF prodding at the USB controller I had finally mapped out all of the necessary pin combinations that I needed to successesfully complete this project (Here is the the Spreadsheet). Now the real fun began. I took apart the apple keyboard optimistically thinking that this might not be too hard.

Once I got a look at the circuit pathways that apple had used, I almost pulled out some hair! Then I grabbed my dremmel and started gouging the board to cut through the circuit pathways and any possibly hidden under the surface. This is why the bottom of the keyboard circuit looks like a checkerboard.

I then began the arduous task of soldering all of the wires to the back of the key contacts. I decided to use on old IDE ribbon to provide me with the wire for 2 reasons:

1. Low Resistance
2. Flexible

Since the angle of the keyboard can be readjusted, it was absolutely necessary to have as much flexibility in the circuit as possible. A few weeks of (here and there) soldering later I had a working keyboard!!! I even ran a wire to the LED in the caps lock key from the control circuit.

Once the keys were soldered into the control board, I discovered a troubling issue. Upon pressing certain keys a ghost key press was produced. For example whenever the "I" or "E" keys was pressed the output produced "IE" this issue was found with several keys. I knew that I needed to include a diode to correct the issue; however I was a bit fuzzy as to the specifics. Upon doing some research I found that the cause of this issue is due to the fact that most keyboards function on a matrix, and when the matrix is scanned if 3 keys happen to occupy the same channels one key press on an individual channel can produce an unintentional electrical bridge to another channel simulating a key press. There is an abundance of Bad and Misleading information on the internet on how to correct this issue, however I found http://www.dribin.org was a refreshing and through insight into the matter. My personal thanks to "dd" for posting this information.

A quote from "dd's" website

"What happens is that closing switch B and switch D at the same time creates an electrical path from C1 to R2, bypassing the open switch C. The keyboard does not know that switch C is open and generates a "ghost" key press. Ghosting will show up when any 3 corners of a rectangle in the matrix are pressed at once. In my simple example, any 3 keys cause ghosting, but in a bigger matrix only 3 corners of a rectangle cause it."

The site goes on to recommend the diode "1N4148" which sell for $0.90 for a pack of 30 at any local electronics shop.

Now on to the case. This was a bit of a pain mainly because there were no function keys on the keyboard. They were located on a secondary keyboard, and if this was going to be usable at all had to be relocated. I cut out the buttons from the plastic housing of the secondary keyboard, and then I cut out the button circuit. Once again I soldered wires to the button terminals and I ran them to the underside of the keyboard to be spliced into the wire feeding the keyboard matrix. I then cut out spaces in the keyboard housing and worked in the function keys using Dynatron flexible bumper repair compound. I then gave it 7 alternating coats of silver and clear coat.

I Love the way it came out, and the action on the keys is AWSOME! For all the hardwork and time it cost me to complete, I realy enjoyed this project and I am especially proud of it.