Let me put it this way: I built my original, working unit during high school one night in my bedroom. It was entirely constructed out of dead toys. The first framework on which the coil assemblies were mounted was a purple plastic Megatron helmet.

Kids, try this at home.

I’m dancing around non-disclosure here, but: most of the early experiments, as well as many current ones, make the mistake of using fields that are far too strong, far too high frequency, and far too diffuse. The trick is not to batter the brain into submission, but to coax natural activation patterns into supporting the induction signal rather than fighting it. There are superficial similarities between our work and light-and-sound machines, binaural generators…indeed some latter-day models incorporated such devices to produce certain effects. You can do neat stuff with LS machines, and probably, if you can figure out how to build one from scratch, you could build a simple version of my device.

http://www.barbelith.com/topic/16658

Over a scratchy speaker, a researcher announces, “Jack, one of your electrodes is loose, we’re coming in.” The 500-pound steel door of the experimental chamber opens with a heavy whoosh; two technicians wearing white lab coats march in. They remove the Ping-Pong-ball halves taped over my eyes and carefully lift a yellow motorcycle helmet that’s been retrofitted with electromagnetic field-emitting solenoids on the sides, aimed directly at my temples. Above the left hemisphere of my 42-year-old male brain, they locate the dangling electrode, needed to measure and track my brain waves. The researchers slather more conducting cream into the graying wisps of my red hair and press the securing tape hard into my scalp.

After restoring everything to its proper working position, the techies exit, and I’m left sitting inside the utterly silent, utterly black vault. A few commands are typed into a computer outside the chamber, and selected electromagnetic fields begin gently thrumming my brain’s temporal lobes. The fields are no more intense than what you’d get as by-product from an ordinary blow-dryer, but what’s coming is anything but ordinary. My lobes are about to be bathed with precise wavelength patterns that are supposed to affect my mind in a stunning way, artificially inducing the sensation that I am seeing God.

http://www.wired.com/wired/archive/7.11/persinger.html