From owner-biophysics@net.bio.net Fri Apr 01 23:00:00 1994 Newsgroups: bionet.biophysics Path: biosci!agate!howland.reston.ans.net!europa.eng.gtefsd.com!emory!news-feed-2.peachnet.edu!concert!hearst.acc.Virginia.EDU!murdoch!galen.med.Virginia.EDU!jbt6w From: jbt6w@galen.med.Virginia.EDU (Jeremy B. Tuttle) Subject: Re: Question:Vibration Message-ID: Sender: usenet@murdoch.acc.Virginia.EDU Organization: uva References: <199403181845.KAA02478@net.bio.net> Distribution: bionet Date: Thu, 31 Mar 1994 16:33:31 GMT Lines: 26 Vibrations in a recording set-up are usually due to two sources: 1) A moment or weakness in the system for holding the preparation and recording electrode. 2) A resonance in the set-up to a dominant building frequency. The first is solved by making sure the electrode is sufficiently coupled to the recording stage to prevent idendependent movements. The second is solved by decoupling the set-up from the building, ie. providing no resonant frequencies in common with the building. This is often accomplished by springing a mass on a cushion with a very low resonant frequency. So - it's common to see a 1" steel plate with magnetic holders, microscope, etc all mounted (no moment) and the whole floating on Barry-mounts (inflatable shocks), an active table, or even small inner tubes, from a wheel barrow, all on a strong table. Operationally, it is best to have only one set of cushions or shock absorbers instead of one under the table and one under the sprung mass. -- Jeremy B. Tuttle, Ph.D. tuttle@virginia.edu or: jbt6w@virginia.edu Associate Professor of Urology and Neuroscience Box 230 University of Virginia Hlth Sci Cntr TEL: 804 924 5634 Charlottesville, VA 22908 FAX: 804 982 4159 .