This is just a quick lesson that expands a bit on the "button" lesson earlier. I just got a bunch of new toys and wanted to do something with one of them this evening for you.
If you want to buy one of these, here's the one I picked up, or you can just go to eBay and search for 4x3 matrix array keypad. These are a DOLLAR, or less in quantity.

Here's the article with video on the blog
If you want to buy one of these, here's the one I picked up, or you can just go to eBay and search for 4x3 matrix array keypad. These are a DOLLAR, or less in quantity.
Here's the article with video on the blog