Create External Buttons for Your Keyboard

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Here are the materials and tools that you will need for this project.

Materials
Keyboard
Large Push Light
Masking Tape
Thin Insulated Wire

Tools
Wire Strippers
Knife
Screw Driver

Start by removing the screws on the back of the keyboard and opening it up. Inside you will find several sheets clear plastic. The top sheet and the bottom sheet will have etching that resembles a circuit board. These are the button contacts. The middle sheet is plain but has a hole at the location of each contact. This sheet acts as an insulator between the top and bottom sheet.

The etched plastic sheets connect to a small circuit board. Whenever a button is pressed, the contacts on the plastic sheets touch and the circuit board registers key stroke.

Locate the contacts for the key that you want to be able to activate with an external switch. Larger keys like the space bar may have more than one contact. 

Take a pair of small insulated wires and strip the insulation off of the ends. Place the exposed copper wire over the keyboard contact. Then tape it down with a piece of masking tape. Try to tape it down tightly so that it makes a good connection. Do this for the contacts on both the top sheet and the bottom sheet. 

Now you need to test it. Plug the keyboard into your computer. Then take the free ends of the two wires and touch them together. If everything is working properly, the computer should register the key stroke just as if the button had been pressed on the keyboard.

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To route the wires outside of the keyboard, we need to cut a slot in the housing. Hold the wire up to the edge of the housing where you want the slot to be and mark the edges. Then use a sharp knife to cut a slot for the wire in the side of the keyboard.

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Now you need to find a switch or button that you can connect to the wires and use to activate the keyboard. This can be any kind of switch. I chose to use the switch from a small push light. But you could also use any small push button switch. You could use a magnetic reed switch. You could even use a pressure plate.

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You need your switch to be a momentary switch. If the switch latches and stays in the ON position it will just be like someone is holding down the key on the keyboard. But if you have a latching switch that you would like to use, you can often modify it so that it acts as a momentary switch.

To do this, start by taking apart the housing of the switch. Be very careful not to lose any small pieces that might be inside. Somewhere inside the switch, there will be a pin or a hook of some kind. This is what latches the switch and holds it down. Carefully remove this pin. Then carefully reassemble the rest of the switch. Be sure to get all the small parts back in their original locations. If all went well, you should now have a momentary switch.

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Now you just need to connect the switch to the wires from the keyboard. To do this I cut the wires that connected the switch to the light and I stripped the insulation off of the ends. I inserted the wires from the keyboard through the mounting hole in the back of the push light. Then I soldered the wires together. To help keep the solder connections insulated, I wrapped them in tape. 

After making these connections, you should again test it. Plug the keyboard into your computer and press the switch. If everything is working properly the computer should register the keystroke.

Now just reassemble the housing of both the keyboard and the button. Try not to disturb the wires too much in the process.

Now you just need to find a few creative ways to use your new external keyboard buttons. The simplest application is to just use it to scroll through Reddit or to start and stop your music player. Or you can use it or gaming. That way you can control character movement, aim and hit commands all at the same time. You can also use it to help data logging. You can easily count the number of times that an event happens using a spreadsheet. Just count the number of times that a letter is typed. This design also makes it easy to set up controls for people with limited mobility. 

The only down side of this design is that you can't use that key on the keyboard while the external switch is attached. So if you want to be able to still type on the keyboard like normal, then you need to two keyboards. One will let you type and the other will have the external switches connected. This shouldn't be too much of a problem because you can get cheap keyboards at a thrift store and most computers have plenty of extra USB ports to use.

Most problems that you will experience are caused by a loose connection between the contacts on the keyboard and the wires. There are several ways that you can deal with this.

You can make the connection tighter by applying more tape. You can use a paper clip to hold the wire tightly against the contacts. Just cut a small hole in the plastic that will let you slide half of the paper clip to the other side of the plastic. You can also use conductive glue to attach the wires. If all else fails you can trace the wires back to where they connect to the circuit board and solder the wires directly to the circuit board.