Poor Man’s DIY Makey-Makey
This post isn’t a guide, as much a proof of concept. I’ve tested it minimally. Makey-Makey’s are great, and I highly recommend buying some if you can. But if you want to try a project with your kids and see what comes of it, I think it has potential.
Most have now heard of the Makey-Makey, gator-clips and a USB board that turns things into inputs for computer(i.e., game controller out of bananas). I sat down today to think through a plan for a summer camp that would use a similar concept, but buying the kits just seemed too easy, and used money that I didn’t have in my budget. With some ninja-googling, I stumbled on this guide. Essentially, it covers breaking apart a USB keyboard, and repurposing the pins to do what you what. In my case, it was going to be a poor-man’s makey-makey.
If you’ve not taken apart a USB keyboard before, you may be in for a surprise. There isn’t a whole lot in those plastic shells. You’ve got three sheets of plastic. Two of them have conductive dots, and a third lays in-between with holes punched in it. When pressure is applied, the contacts on the outer sheets connect through the holes in the middle sheet.
Here’s the interesting part. All of the conductive dots are connected by lines. Each one going back to 1 of 20-ish pins. The top sheet has a set of pins, and the bottom sheet has a set. A board, the size of a matchbox car, matches the pin pairs and sends the assigned key. With the power of a sharpie, these lines can be traced back, and a matrix written out to show which keys are assigned to which pin pair. At this point, you can figure how many keys can be traced back to a single pin. Solder your wire to that pin, then add wires to each of the other pins. The other pins become your clips to attach to bananas, and the other wire is what will make the pair to send the keystroke.
This should give you several keyboard characters that you can use in Scratch to do just about anything that requires a button press. My first goal, is a stairway piano. Should you do this and beat me to it, snap a picture or video and let me know how it goes.