parkerl:
I am attempting to run a brushless dc motor using a Mystery electronic speed controller (see picture). I have been unable to get any sort of reliable results; at best the motor will spin up for a few seconds then stop for long periods. I am using the standard Arduino servo library on the Arduino Pro. Does anyone have any experience with these motor controllers? Google searches haven't returned any useful information as to what input they expect. Any help would be much appreciated.
I've used the very same model of ESC without such issues (although one blew up on first test!).
You may well be triggering shutdown in the ESC - these controllers are generally v. reliable devices, but they take on the role of detecting possible failures in other parts of the system and powering down if a fault is suspected. This is vital in RC plane application. For instance the command input to the ESC should be a smoothly varying signal, should start at throttle-off.
The battery voltage is monitored by ESCs and they will reduce power and then stop if the battery voltage drops beyond set limits.
If you are not using an RC LiPo or NiMH battery pack to power the motor and ESC you are likely to have problems since peak current demands of tens of amps need to be met. You need to ensure all high-current connections are sound (the currents are beyond the ratings of most standard connectors, the specialized ones used for RC models are good, as are screw-terminal connector blocks)
So first check the battery and wiring is up to the task, then check your code doesn't change the servo output value in large jumps, ramp it up smoothly.