Buzz
If you own a cell phone or pager, you're aware that having it ring during a movie or performance could lead to a serious situation in some places. Devices that vibrate in place of the ringer are not only convenient but crucial for urban survival, offering a quiet alternative that can be life-saving in certain contexts!
One device takes vibration technology to the next level. Any parent with a child who has a Tickle-Me-Elmo doll has seen this in action. Elmo uses a vibration system (designed to mimic body-shaking laughter) that’s powerful enough to make many kids drop the toy. The vibration system in a pager works similarly, only on a smaller scale, so let's consider Elmo as our example.
Here’s a Tickle-Me-Elmo doll:
A little dissection shows the control unit inside:
The control unit (on the right side in the image above) contains a small DC motor that powers this gear:
Attached to the gear is a small weight, roughly the size of a stack of five U.S. nickels, positioned off-center. As the motor spins the gear and weight combination (at 100 to 150 RPM), the off-center position creates a noticeable vibration. The same kind of mechanism, only much smaller, is found inside a cell phone or pager.
