On Fox News a week or two ago, there was a doctor who had a magnetic pulse
device he was using to treat severe depression. The transducer was what
appeared to be a ferrite C-core with perhaps a dozen turns of heavy wire,
connected to a cable running to a large cabinet. The device made cracking
noises (capacitor discharge?) at about a 5 to 10 Hertz rate.
He was heard saying to the patient that she would notice twitching in her
extremities when he found the right spot..
It actually seems to do some good, but I have no idea whether there have
been any actual studies done to remove the placebo effect as a reason.