Sunday, April 18, 2010


I got Issue 22 of Make on Friday, wherein is contained a project for a cat toy that "senses and Twitters felinogenic perturbations". (Heh.) I recently discovered -- while making a cigar box guitar from Issue 21, naturally -- that one of our cats, Sammy, luuuuuurves to play with guitar strings, since they dance all around and hold up well to clawing and nomming, being made of steel and all. As the cat toy project mostly consists of a paper bird on the end of a guitar string, I figured this one was a no-brainer.

It's a pretty straightforward project, although I did encounter one snafu. The core of the project is just a steel molly bolt installed into an enclosure, with a steel guitar string projecting up through the center. When the cat whacks the toy, the guitar string bends and makes contact with the molly bolt, which closes an electrical connection. It turns out to be a bit tricky to get the guitar string, molly bolt, and heat-shrink tubing lined up correctly so that the guitar string is not in contact with the bolt while at rest yet still makes contact easily when whacked. I ended up screwing up the first attempt and had to try again. But, I got it to mostly work on my second try.

Now, I'm no dummy. I know better than to spend hours soldering up a whole project, installing it into an enclosure, and then writing Arduino code for a cat toy, before finding out if the cat actually likes it. (Measure twice, cut once, as it were.)

So instead I took a decapitated USB cable that I have lying around that I use to prototype with a breadboard, and hooked up USB power/ground to the breadboard, and an LED in series with the toy's signal leads. I then plugged it into my laptop, which made for a quick and dirty 5V power source for testing.

The LED lit when I whacked it, so everything seemed installed correctly. I whacked it around a few more times watching the LED light up, until I realized I was playing with a cat toy. *ahem*  I then went to find Sammy.

By now the astute reader knows where this is going, of course. Sammy would have nothing to do with this thing. He could tell I wanted him to play with it (since I kept picking him and putting him back in front of it whenever he started to walk away), so he batted at it half-heartedly a couple times, then looked at me and meowed for dinner.

To confirm, I grabbed another guitar string and held it out for him, and boy howdy did he have a good time with that one. The toy, unfortunately, just doesn't have enough whiplash action to interest him. Since it stands vertically, the string's length has to be short so that it doesn't bend over under its own weight, but Sammy likes his strings to be full-length, I guess.

So, today I made a cat toy that was more entertaining for me than for the cat. My name is Dan, and I'm a Maker.  (Hello, Dan!)

All is not lost though, I have a couple ideas for how I can make a variant of this thing that Sammy will like. I think I will use a dowel for a hard vertical shaft with the guitar string placed horizontally on the top. Pulling on the string will make the dowel lever back and forth, which I can use to trigger a switch. This might actually even be easier and more durable than the vertical version, and has the advantage of not electrically connecting the cat to 5V DC.

When (if?) I get this working, I doubt I'll use it to Tweet, though. Or at least, if I do I intend to at least use it to trigger a webcam that grabs a snapshot or video of the cat at play. In this era of "video or it didn't happen", can I do any less?

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