PSN-L Email List Message
Subject: Re: Magnetic Phono Cartridge as a Seismic Velocity sensor ?
From: ChrisAtUpw@.......
Date: Tue, 11 May 2010 19:03:25 EDT
In a message dated 11/05/2010, gmvoeth@........... writes:
Might one use a magnetic phono cartridge as a seismic sensor.
Hi Geoff,
Phono cartridges are designed to do a very different job. The motion
is measured in thousanths of an inch, the frequency is the normal audio
range, the output is in milli volts and they use a ferromagnetic backing plate.
For a vertical pendulum you need at least +/-0.5 mm movement and for a
garden-gate pendulum +/-10mm movement with good linearity. The frequency
range is 10 Hz downwards, often to less than 0.05 Hz. These are not
difficult to construct using inexpensive NdFeB magnets. For a vertical pendulum you
can also use a Hall Effect magnetic sensor eg Allegro A1321.
Regards,
Chris Chapman
In a message dated 11/05/2010, gmvoeth@........... writes:
Might=20
one use a magnetic phono cartridge as a seismic=20
sensor.
Hi Geoff,
Phono cartridges are designed to do a very=20
different job. The motion is measured in thousanths of an inch, the freque=
ncy is=20
the normal audio range, the output is in milli volts and they use a=20
ferromagnetic backing plate.
For a vertical pendulum you need at least +/-=
0.5 mm=20
movement and for a garden-gate pendulum +/-10mm movement with good lineari=
ty.=20
The frequency range is 10 Hz downwards, often to less than 0.05 Hz. These=
are=20
not difficult to construct using inexpensive NdFeB magnets. For a vertical=
=20
pendulum you can also use a Hall Effect magnetic sensor eg Allegro A1321.<=
/DIV>
Regards,
Chris Chapman
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