We came across this small 3x4 keyboard matrix which we had to use in this one project. Datasheets and all relating information had been lost a long time ago so we had no idea how it was connected. Velleman currently sells 3x4 keyboards, but with common output. However they look very much the same as our keyboard so we can probably assume that this these too came from Velleman... Well now to the point of this article; Because we had to figure the connection out by ourself, we decided to publish the diagram and save anyone else from the same trouble.
More information about keyboard matrices can be found for example from here: http://www.dribin.org/dave/keyboard/one_html/
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