VKey Voltage Keypad Hookup Guide
This Tutorial is Retired!
This tutorial covers concepts or technologies that are no longer current. It's still here for you to read and enjoy, but may not be as useful as our newest tutorials.
Byron J. 
Resources And Going Further
The VKey is a great way to add up to 12 buttons to a project, while still leaving many I/O pins for other tasks.
For more on the VKey Voltage Keypad, check out the links below:
Modifications
There are a number of possible alterations that can be made to the VKey, to tailor it to a specific application.
Different Switches
The VKey comes with 12 PTH pushbutton switches, but can support nearly any normally-open SPST switch, such as arcade buttons or microswitches.
To connect other switches, connect them to the pair of pads on the left of the tact switch footprint, as seen from the front of the board.
Voltage Source
While the VKey is primarily intended to interface with a microcontroller, that doesn't mean it can't be used for other applications. The circuit is similar to those used in analog synthesizers to extract a control voltage from the piano keyboard. You could use the VKey to drive any device with a control voltage input.