I’ve had this project sitting around for ages now. An automated way for the cats to have their laser fun without having to sit there with the laser pointer. (We get tired before they do, and by “we” I mean Evelyn.)

I got one of those DART laser toys, and they are pretty good. But have one huge drawback (besides sucking up batteries) — while their motion is random, they only draw the laser in a circle. The cats, of course, figure this out VERY quickly. So, being the lazy kids that they are, end up sitting around the DART and just pawing as the laser goes by. So much for exercise!

I was originally going to attach mirrors to two servos, then shoot a laser at them. One X, one Y, so you’d be able to “draw” with the laser beam. But you get a lot of power loss when you bounce off my cheapo mirrors (didn’t have any front surface mirrors on hand, and they are expensive and easy to damage).

So, I went searching again and found a design where the laser is mounted directly to one servo (to provide X) and the servo/laser combo is then attached to a bigger servo (to provide Y). Think how those robot welding arms work, and you get the idea.

This Instructable shows you what I mean: CatBot

Here is my work in progress.:

Toward the upper right, you see the laser module I scavenged from a dollar store laser pointer. It’s hot glued to a little servo. That little servo is zip tied and hot glued to a piece of erector set. The bottom piece of erector is screwed to the bigger servo (which is, for testing purposes, clamped in a vise).

I originally was trying to drive the laser using a 3.3V regulated supply. But, there are no specs on the laser, and I blew up two by over driving the current. This is why I use dollar store lasers. So, I went the hillbilly route and used a 3V coin cell. I call it hillbilly because you can see my header pin kludge to hold the cell. I tossed a switch on there so I can manually shut the laser beam on/off.

Toward the left is my go-to board for Arduino development. The Evil Mad Science Target Board. Because these servos don’t take too much current, I’m driving them directly off the Arduino pins. PWM (pins 9 and 10) handle the yellow/white signal line. I use the servo library to drive the code, so that’s pretty simple.

Now Evelyn is laser cutting a box to put the big servo and control board into. This will then get mounted on the ceiling, with the laser moving all over the house.