I wanted to put a kick pedal pad up top to use with the drum stick. So I cut up an old IBM number pad off a keyboard, wired it to a mono 1/8" plug, and now I have a pretty indestructible "extra pad" to use along side the kick pedal. And I made it with stuff I had laying around!
Step 1: Materials... Cut Off the Number Pad From a Keyboard.
You will need an unwanted old wired computer keyboard... a nice durable older one.
An 1/8" Mono audio wire. $4 www.radioshack.com/product/index.jsp
A mono or stereo "Y" headphone jack splitter. $4 www.radioshack.com/product/index.jsp
Hot glue gun.
Wire clothes hanger.
Cut the number pad off with a jigsaw or a dremmel.
Step 2: Take Apart the Keypad and Check How the Switchs Work.
Take out any screws in the back of the keyboard, and carefully pull apart the layers of the keyboard.
Here are the layers:
The outside buttons.
The rubber layer that push the buttons back up.
Top pressure switch layer (thin plastic with wires etched in like a circuit board.)
Plastic separation layer.
Bottom pressure switch layer.
Bottom of the keyboard.
If you trace the upper switches you can see the individual etching that connects each button to the keyboard chip. The goal is to connect as many of the tracings together on the top layer with one wire, and the same with the bottom. The bottom layers are all attached together anyway, so in theory you only have to get a good connection on one wire... but the more the merrier... you are going to be whacking it with a drum stick!
Step 3: Cut the Wire and Solder It.
Cut the 1/8" mono headphone cable in half, and strip back 2 inches of the black outer coating. I used my teeth. Strip off 1 inch of the inner wire coating, and spin all the outer copper ground wires together to make it a single wire.
With the 1" inner wire, carefully solder it to the underside of the top layer (you can feel it is bumpier on the underside) and melt through the plastic a little to attach as many of those wires together. Hot Glue the connection to hold the wire to the plastic board. Do the same thing to the top of the bottom layer. Make sure not to melt anything in any other layer than what you are working on...
Step 4: Test It.
Google "Rock Band Drum Machine" and install the nice software Andrew Rudson made (free) to test the new pad. Unplug the kick petal and plug the keypad in. Check and make sure it works before you put it all back together. You should be able to just line up the layers and use your finger to complete the circuit.
Unplug it from the kit before you solder. There is no power going through the switches so you should not damage anything. But try it at your own risk. If it satisfactorily works (at least a few keys close together)... hot glue any exposed wires, and hot glue where the wire comes out the side to make sure you can't pull it free.
Step 5: Make a Rack to Hold It.
Take one wire hanger, bent the hook down to the bottom and bent the sides under the pads. Rubber band the hanger in place, and then rubber band the keypad to the hangers. It is pretty strong and has some give when you hit it with the stick. Plug the "Y" adapter in and you can use the pedal and the keypad at the same time.