CELL-PHONE TOWER

A cell-phone tower is typically a steel pole or lattice structure that rises hundreds of feet into the
air. The box houses the radio transmitters and receivers that let the tower communicate with
the phones. The radios transmitters and receivers connect with the antennae on the tower through
a set of thick cables. The tower and all of the cables and equipment at the base of the tower are
heavily grounded.



HOW VIBRATOR WORKS IN CELLPHONE

If you have a cell phone or a pager, then you know that having it ring in the middle of a movie or
performance is enough to get you killed in some cities. Vibrating devices that quietly replace the
ringer are therefore life-saving devices that are an important part of urban survival!
Figure below shows the inside of a small toy which vibrates heavily similar to a cellphone
device.

Inside the control unit is a small DC motor which drives the gear. Attached to the gear, there is a
small weight. This weight is about the size of a stack of 5 U.S. nickels, and it is mounted
off-center on the gear. When the motor spins the gear/weight combination (at 100 to 150 RPM),
the off-center mounting causes a strong vibration. Inside a cell phone or pager there is the same
sort of mechanism in a much smaller version.