I got an Uno starter kit about a month ago and have been having fun running through the tutorials and learning about electronics. Then I found this old toy in the thrift store. Someone had switched it on and I could hear a motor turining inside, but no movement from the wheels. I thought it would be fun to try and fix it up or at least salvage the parts.
It turns out the toy was intended to entertain cats. The original toy was basically an rc controlled mouse (or cat) that had a stuffed mouse on the end of a wand. It could move forward, do a clockwise turn in reverse, and randomly move wand thus jerking the stuffed mouse around. Basically it played with your cat for you. The one I found in the thrift store was missing the wand and the IR remote that was used to control it.
Video of the original toy: https://www.youtube.com/watch?v=-2a30Gdn3Vk
Closer examination showed that they toy had a "sensor" mode in addition to just being switched on. I'm not sure what it was supposed to do. Looking inside I could see 2 motors, an IR receiver, 3 photoresistors, and a PCB with 2 EMD812 ICs. Since there is no good way to know what IR codes where used to control the motors, I decided to see if I could bypass the IR controls by soldering a signal wire directly to the EMD812.
Success! I was able to engage the motor that controlled the wheels. Unfortunately, the toy's fuse blew while trying to drive the motor for an extended period. Bummer...at that point I decided to forget about reusing the emd812s and go with the L293d that came with my kit.
I tested the two old motors from the toy and found the one that blew the fuse was drawing a lot of mA and behaving erratically. So I figured that motor was bad. I replaced it with the other old motor.
I tested the old photoresistors and the IR receiver. They still work! I learned the hard way about interference from the motors affecting the IR receiver. I knew my code was good.
Anyway it's been a fun journey of learning. I am at the point now where I have a working motor and remote control. My next steps are to:
- install a switch to turn off (better than removing batteries)
- install the photoresistors
- write code to automate the mouse based on photoresistors (maybe move toward darkness - like a real mouse?)
- try to get it all to fit in the orginal housing
Cheers,
Bill