I bought some of these: http://www.tcs-motor.com/en/product-details-193.aspx info shows 3vdc and 115ma
My test rig is as follows. Uno pin 11 with analogWrite value 127 ie im trying to get 50% duty cycle. This goes to base resistor of a 2n222a, emitter to gnd, collector to -ve terminal of device, +ve of device to 5v. The setup is exactly as I would have for buzzer or relay, lazily ommitting flyback diode.
I cant get any airflow in or out of the damn thing. I have varied base resistor, duty cycle, and even used an external psu at 5v, 6v even 9v.
I have measured current through the beast at e.g. 100ma with 6v in @ 50%. This seems to me to be ideal operating point., but no airflow. I even had 175ma through it at 9v with 2.2k base resistor...still nowt.
Other points...I tried 2 or 3 to rule out a dodgy unit. Same results. In all cases mentioned above the unit buzzes (appropriately for the duty cycle if u know what I mean) so it sounds/seems like the thing is working...but it aint! I even dismantled one to see if it had its own oscillator like an active buzzer, but all there is is a magnet and sprung moving coil.its like a tiny loudspeaker in fact minus the cone.