> > Sensor: Golitsyn pendulum + moving coil transducer. .... > Could you take a picture or give a little more explanation about your > instrument please. I don't think I've heard of it before. It seems the original "Lehman" instrument was developed a long time ago by Boris Golitsyn. Quoting from http://psn.quake.net/sgsenstxt.html which quotes from September, 1975 Scientific American Magazine "The Amateur Scientist" the following " When an amateur builds a seismometer, he is most likely to choose an instrument of the electromagnetic type developed in 1906 by Boris Borisovich Golitsyn, a physicist who was also a prince of the Russian Empire. A seismometer of this type picks up earthquake waves with a pendulum that supports a coil of insulated wire between the poles of a magnet rigidly linked to the earth. The relative motion between the magnet and the coil caused by tremors in the earth generates corresponding electric currents in the coil. The currents can be amplified to operate a pen recorder. " As best I can determine, Lehman in the late 1970's described a particular two vertical strut instrument that he made. Somehow his name stuck to the generic "garden gate" or " Golitsyn" type instruments ever since. I believe that it is mostly PSN folks that use the term Quoting from http://www.seismicnet.com/info/homefaq.txt "CONSTRUCTION INFORMATION - INSTRUMENTS & SENSORS: A very good article was published several years ago in the AMATEUR SCIENTIST by Scientific American. Titled, "How To Build A Simple Seismograph to Record Earthquake Waves at Home" by Jearl Walker. The article was published in Scientific American, 1979, v. 241, No.1, pg 152-161. It described the construction of a horizontal seismic sensor and preamp circuit designed by James D. Lehman. At the time, Mr. Lehman was with the Physics Dept., James Madision University, Harrisonburg, Va., 22807. " The June 1953 issue of Scientific American, "The Amateur Scientist", conducted by Albert G. Ingalls, described a Golitsyn type seismometer - using a vacuum tube amplifier. The availability of amplifiers removed the need for the large mass and some "interesting" circuits to facilitate recording of the early 1900s electrical or mechanical designs. Certainly by 1953, many commercial seismometers were using the "garden gate" or " Golitsyn" design. Most of these designs use a single rigid vertical strut. I have no idea what advantage the Lehman two small vertical strut design has other than the local hardware store might not have large enough diameter copper tubing. Cheers Ed Thelen _____________________________________________________________________ Public Seismic Network Mailing List (PSN-L)
Larry Cochrane <cochrane@..............>