Hello, Marshall, For those who wish to make their own, Beck gave a design using an air-core cross-over coil of about 2.5 millihenries of inductance. Such coils are off-the- shelf items used by audiophiles for their loudspeakers to avoid the distortions that comes with saturation of iron-core coupling transformers. Beck mentions a vendor, MCM Electronics of Centerville OH 45459 and a particular coil, the 2.5mH, 0.58 watt #50-940. It cost $10.65 in 2000 but has gone up in price since then. MCM does stock larger air-core cross-over coils than this one, though. A pair could be used to channel magnetic flux into deeper tissue, or to concentrate flux of N or S polarity if that is desired.Beck's design uses a photoflash camera attachment using DC batteries, though I think an AC-powered party strobe might be handier (I found one for fifty cents at a yard sale.)
Best regards, Matthew
