I would like to make a vibrobot similar to this one. But probably a bit larger and somewhat "clever". I was looking at vibration motors on eBay and found very little characteristics. For less soldering I would like to power them directly from a pin. (I am a bit afraid joints will suffer from the vibrations.) I don't know which motor to choose. For example description of this one says maximum 70mA @ 3V. Another one consumes 0.15-0.23A @ 1.5-3V. But this one needs only 12mA @ 3V. I don't know how to understand those numbers. I would expect vibrations ~ I.U so the last one would vibrate much less than the first two. On the other side trying to source large current from the pin will lead to voltage drop so the motor will consume less current and be less efficient...
I also tried to find more info about vibration motors. Here I have found some interesting stats about 8x2.5 mm flat motor. There is this graph:
It looks like until the motor starts at about 2.4V there is no current. Then current consumption and speed quickly rises and when current is around 40mA it needs more voltage to operate but efficiency decreases. Is it "normal behavior" of motor or is it just artifact caused by not characterizing motor at voltage under 2.4V?
Also second page of this motor states "Typical Start Current: 60 mA at rated voltage". Does that mean the graph is for consumption of the motor when running but it will not start until it gets 60mA? Or will it just start slower when the current is not limited?
Do you have some experience with those motors and hints what to look for? For example if the flat motors are somewhat better than cylinder motors or vice versa?