PSN-L Email List Message

Subject: Re: Magnetic Phono Cartridge as a Seismic Velocity sensor ?
From: ChrisAtUpw@.......
Date: Thu, 13 May 2010 08:19:04 EDT


In a message dated 12/05/2010, gmvoeth@........... writes:

i just  cant help but think there is a very simple way to do this that does 
not  require a mass and spring. Such as a strain guage and a mass, resting 
upon  it.
Hi Geoff,
 
    Strain gauges have too low an output.

You set  some mass on something like a bathroom scale and amplify the 
output from the  scale.
    These are likely to have too much in-built  friction.

Touch a  Phono Needle to the bottom of a mass on a spring. Why not get a 
meaningful  signal.
It should work just like any velocity sensor. Sum the outputs of a  stereo 
cartridge.


I told you three good reasons why a phono cartridge  would make a lousy 
seismic sensor. If you don't believe me, OK. Waste your own  time, effort and 
money, but don't waste that of other experimenters.
    You can make a seismic sensor with a large PZT  sounder disk and a mass.
 
    Regards,
 
    Chris Chapman





In a message dated 12/05/2010, gmvoeth@........... writes:
i just=20 cant help but think there is a very simple way to do this that does not= =20 require a mass and spring. Such as a strain guage and a mass, resting up= on=20 it.
Hi Geoff,
 
    Strain gauges have too low an output.
You set=20 some mass on something like a bathroom scale and amplify the output from= the=20 scale.
    These are likely to have too much in-built=20 friction.
Touch a=20 Phono Needle to the bottom of a mass on a spring. Why not get a meaningf= ul=20 signal.
It should work just like any velocity sensor. Sum the outputs= of a=20 stereo cartridge.
    I told you three good reasons why a phono car= tridge=20 would make a lousy seismic sensor. If you don't believe me, OK. Waste your= own=20 time, effort and money, but don't waste that of other experimenters.
    You can make a seismic sensor with a large PZ= T=20 sounder disk and a mass.
 
    Regards,
 
    Chris Chapman

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