safe way to attach coin vibration motor to arduino

In another one of my posts someone kindly pointed out that my vibration motor is drawing more mA from the arduino than is safe.

data sheet: http://www.sparkfun.com/datasheets/Robotics/310-101_datasheet.pdf

what is a safe way to use this motor... i am using both arduino uno and duem

thank you

w

use an H-bridge (http://library.solarbotics.net/circuits/driver_4varHbridge.html) in the picture, attach input a and b to arduino pins.

Thank you.

Is this something you can buy or need to build yourself?

As the motor is only to generate vibrations (no shaft) then there is probably no need to run it forward and backward. A simple transistor will do the job http://ctheds.wordpress.com/2007/10/30/tip-120/ The motor is only 2.5-3.8 volts so you will need a suitable way to power it. The UNO's 3v3 output is only rated to 50mA so is not suitable

Using an h-bridge can improve haptic performance (reversing the polarity stops the motor quicker), but as Riva mentioned there's no need if your doing simple vibration alerting. Tonnes of advice from the motor's manufacturer:

Discrete driver circuit http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-001-discrete-driver-circuits-for-vibration-motors

H-bridge http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-002-discrete-h-bridge-circuit-for-enhanced-vibration-motor-control-haptic-feedback

Integrated driver circuit http://www.precisionmicrodrives.com/application-notes-technical-guides/application-bulletins/ab-017-integrated-driver-circuits-for-vibration-motors

You can buy MOSFETs from tonnes of electronics shops (depending on your location), e.g. Maplin, Farnell / Element14, RS online, Radioshack. It's also worth checking Ebay, lots of sellers specialising in hobbyist electronics. For the h-bridge you can either build yourself out of transistors (actually a pretty simple build, the schematic looks way more complicated than it is), or buy an h-bridge chip.

A simple bipolar switching transistor, base resistor and a 1N4148 diode will be the cheapest option I reckon.