Subject: Re: Pot and Tube Horizontal Seismometer Are you by chance talking about fLat on water connected by lever rm to a potentiometer ? Possibly a strain guage of some kind ? know there more to it than that, but this should be the basic idea ? ----- Original Message -----=20 rom: "Chuck / Judy Burch"o: ent: Monday, August 01, 2011 10:18 AM ubject: Pot and Tube Horizontal Seismometer Hi Geoff,=20 This is a horizontal fluid seismic sensor, basically consisting of=20 a horizontal tube with both short ends upturned vertically and filled=20 with fluid to about half their height. This is like a small manometer=20 with a long connecting tube. If you accelerate the tube horizontally,=20 the fluid level rises in one end and falls in the other. A fluid=20 restriction is connected in the centre of the horizontal tube to=20 prevent the fluid from oscillating. To get a long period, you either=20 need a very long tube, or you can fit much larger diameter cylindrical=20 cans on both tube ends. One of the easier ways of measuring very small=20 changes in the fluid level is to make the fluid electrically conducting=20 and to insert two vertical wires a few mm through the fluid surfaces on=20 both pots. The coupling between the pairs of wires is measured with an=20 AC voltage, then rectified and the signals from both ends are amplified=20 and subtracted to give the seismic signal.=20 . Regards, . Chris Chapman = Subject: Re: Pot and Tube Horizontal Seismometer
Are you by chance talking about fLat on water connected by lever arm to a potentiometer ? Possibly a strain guage of some kind ? I know there more to it than that, but this should be the basic idea ? ----- Original Message -----=20 From: "Chuck / Judy Burch" <cjburch@...........> To: <psn= list@..............> Sent: Monday, August 01, 2011 10:18 AM Subject: Pot and Tube Horizontal Seismometer Hi Geoff,This is a horizontal fluid seismic sensor, basically c= onsisting of a horizontal tube with both short ends upturned vertically and filled =with flu= id to about half their height. This is like = a small manometerwith a long connecting tube. If yo= u accelerate the tube horizontally,the fluid level = rises in one end and falls in the other. A fluidrestriction isconnected in the centre of the horizontal tube to <= /PRE>prevent <= TT>the fluid from oscillating= .. To get a long period, you eitherneed a very long tube, or you can fit much larger diameter cylindricalcans on both tube ends. One of the easier ways of measuring very small = FONT> changes in= the fluid level is to make the fluid electrically conducting <= /PRE>and to insert two ver= tical wires a few mm through the fluid surfaces onboth pots. The coupling between= the pairs of wires is measured with anAC voltage, then rectified and the signals = from both ends are amplifiedandsubtracted to give the seismic s= ignal..=Rega= rds,.Chris C= hapman