I got magnetic coils from a friend (http://www.diypemf.com/a-simple-pemf-device/), but instead of trying 15 HZ relaxating pulse provided by (http://www.diypemf.com/), I tried 40 HZ isochronic mp3, which as I later understood was differ from original 15 HZ pulse by the way it was modulated. In fact it was 200-300 Hz bearing frequency modulated with 40 Hz pulse. It is big a difference than it is used for magnetic field generation from the situation if it were just 40 hz signal.
So I got 200 hz magnetic field which appeared and disappeared 40 hz a second. I played it from my Iphone on maximum volume.
I applied it to my head and just in several seconds I feel difference inside and after I applied it my frontal lobe I felt really strong stimulated as if I drunk two coffees.
I tried it several times. Once I tried for more than a minute total for several parts of the head and got strange sensations in the parts of the head I touched with coils as well as small sparks in eyes. It all disappeared in half an hour.
I find 15 second applying of one coil to forehead is a good way to fight evening sleepiness.
I am interested to experiment ate with other frequencies and the way of modulation, but I am a little bit afraid that I will fire my brain.
One of the reason that I am not afraid so much is that coils are used in all kinds of headphones in all possible frequensies and not much damage was ever reported AFAIK.