rjk@sequent.UUCP (Robert Kelley) (10/07/89)
In _The_Amateur_Scientist_ section of Scientific American, Feb 1968, page 124, there's a description of a differential magnetometer capable of detecting a minimum difference in field strength of 3e-5 oersted. The magnetic field of the earth causes protons in water molecules to precess at a rate of about 2025 Hz. The article describes a device consisting of two bottles of water with coils wound around them, and a high-gain (2e6) tuned amplifier. A dc current is passed through both coils to align the magnetic dipoles, then the current is removed and the amplifier is connected to the coils. A beat frequency proportional to the difference in the magnetic fields at each bottle is heard at the output of the amplifier. It might be interesting to build a more modern version of the system described in the article. Another installation of _The_Amateur_Scientist_ describes another NMR setup and suggests adding ferric nitrate to the water. Why?
pierson@cimnet.dec.com (10/09/89)
If the interest was in an "early warning" device for Auroral activity, a simpler option is WWV. WWV includes a solar activity report in, in voice, the 18th minute of every hour. thanks dave pierson |The facts as accurately as I can manage, Digital Equipment Corporation |The opinions, my own. 600 Nickerson Rd Marlboro, Mass 01752 pierson@cimnet.enet.dec.com