what is the mechanism inside a cell phone that vibrates it?
thanks
Angry wasps.
NEVER open the case to your cellphone. I’m just sayin’.
It’s a little tiny motor with an eccentric weight on the shaft. The off-balance weight causes the vibration when the motor spins.
Your cheaper phones may use angry wasps. The better phones use a small motor with an off center weight. This vibrates when the motor is running.
Or possibly a motor with an offset wheel that spins rapidly, causing a side-to-side vibration.
But I still wouldn’t open the case, just in case it really is angry wasps.
Not quite side-to-side. In fact, the type of motion induced is, ironically, called gyration. Heh.
It is easy to tell the difference. A wasp phone will make a buzzing sound when it rings. An off centre weight phone will make an heavier note.
Ina ny case, it seems most phones these days are full of angry MIDI musicians. VERY angry MIDI musicians.
Anyone else here carry their cell phone (set on vibrate) in their shirt pocket right over their pierced nipple? No? Oh, uh…me neither. 
So the gyrations of the eccentric weight angers the wasps, causing the phone to vibrate? Or what?
For some it doesn’t matter if you never open the case. You will still get stung when you open up the bill.
Some pictures here. The motors, not the wasps.
Video game controllers use the same technology. If you have a translucent PS2 controller, you can see the weights and motors inside - one side has a smaller weight for light vibration, and the other has a bigger weight for powerful rumbling.
A warning that the link went to a place called “VIBRATORS - MOTORS” and thus maybe NSFW might be warranted.
Not wasps…
[HomerSimpson]
BEES!
[/HomerSimpson]
So…
On phone ring, do the angry wasps
All gyre and gymbal in the case?
All whimsy are the Straight Dopers
who fear their phones uncased.
Beware the jabber-talk, my son…