MouseAir launches toy mice for the amusement of cats

Mouse Push Solenoid

After the mouse has dropped from the loading tube, it needs to be pushed into position between the motors that launch the mouse. I appropriated an inexpensive and rugged two-wire 12V solenoid that is used inside car doors to push up door locks. If you energize it one way, it shoots out, and if you reverse the polarity, it pulls back in. A set of two relays to swap plus and minus accomplished the push and the pull. Originally, I bought this solenoid to launch the mouse from MouseAir, but I quickly found that it just didn't have enough energy to fire the mouse more than a few inches. However, I later found that it provided plenty of energy to move the mouse between the thrust motors.

Thrust Motors

One of the most interesting parts of this design was figuring out how to provide enough energy to shoot the mouse through the air. I looked at some pneumatic designs, such as those used for potato guns (too messy and hard to control); at direct solenoid pushes (old pin ball machines use 50V to throw balls around, but I wanted a 12V system), and at some kind of cocked, spring-loaded throwing arm (this idea would have worked and would have looked very cool, but it also would have been a bit more dangerous). Finally, I saw a ping-pong-ball-launching machine that used two motors to accelerate the ping pong balls.

I determined that inexpensive 12V DC motors with some medium-hard plastic wheels would work with my projectiles and that 7,750rpm motors were more than I needed. A optimally placed mouse will go more than 7 meters with no problem at all. Figure 7 shows a mouse ready to be launched by the solenoid and motors, and Figure 8 shows the completed project

Figure 7: A toy ready to be launched.
Figure 8: The completed MouseAir prototype project.

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