Keypad: The Matrix Decoded

[Homebrew]

Well i don't know about decoded, but hacked.  I've been reading the threads regarding keypads and wiring them and found that matrix keypads were a bit of a pain to hookup to a normal keyboard encoder.   However, cost being a concern, i set out to make one work.  I decided on this keypad i believe i found in one of the threads:
http://www.jameco.com/cgi-bin/ncommerce3/ProductDisplay?prmenbr=91&prrfnbr=347300&cgrfnbr=501&ctgys=

After hours(too many) of messing with it, I finally have a working product.   To save others this headache and to offer a cheap keypad solution, I threw together a pic showing the modifications that need to be made.  This is specific to this keypad, but someone might find it usefull.  


Here's the breakdown:
Red Circles: Connect Positive wires to each one of these contacts
Green Circles: Connect Ground wires to each one of these contacts(or you can daisy chain them together).
Yellow Line: These represent cuts in the traces of the PCB.  

With this diagram, it shouldn't take more than about 20 minutes or so to wire depending on your soldering skills/tools.  I'm not an electronics guru so if anyone sees flaws in my diagram, please let me know.   All in all not a bad keypad for $15 IMHO.  Now all i have to do is build the jukebox its going in  .  I hope this turns out usefull to someone.

-Kevin

[JamIt]

Homebrew,
This is great.  Your work and documentation is very appreciated.
--JamIt

[Homebrew]

UPDATE:
While fooling with it on christmas, i noticed that pressing 8 or 0 would set both off.  Quick fix, just had to make one more trace cut and that was it.  The original post's pic now reflects the correction, but for anyone that needs to see which is the new cut, here's a pic.  


Both pics show all the changes that need to be made to the keypad for it to work, this second pic just points out the new cut i added to fix the 8 and 0.  for anyone that may have attempted this already.  The keypad now works exactly how its supposed to.  Its a bit of work, but it does yield a cheap keypad that IMO is pretty nice looking.  Enjoy!

-Kevin

[mac188]

Has anyone got the pics to do this mod? Thnx in advance

[BobA]

Cannot find the pics for this one anywhere.   From what I remember he went on the back of the keypad and cut the traces to isolate the separate keys so they could be connected to a regular encoder.   He soldered wires on the back of the keypad much like you would do if you were modding a gamepad that did not have an identifiable common ground.  Each matrixed keypad will be different in this respect depending on the arrangement of the keys and the matrix.

[mac188]

Thanks for looking. I had the pics and instructions saved on my pc back when these were posted, but I  had a hard drive crash, and lost them.  Trying to get my project started up.