PSN-L Email List Message

Subject: Re: Instrumentation Question
From: Geoff gmvoeth@.........
Date: Tue, 01 Jan 2013 07:12:15 +0000


On 12/31/2012 6:40 PM, chrisatupw@....... wrote:
> From: Geoff 
> To: psnlist 
> Sent: Sun, 30 Dec 2012 23:14
> Subject: Re: Instrumentation Question
>
> There must be some kind of strain gauge where you simply hang a weight 
> like a pendulum
> and any swing however slight would create a signal.
>
> ****Strain gauges give quite a low sensitivity.
>
> Then the signal would be omnidirectional which is what I am looking for.
>
> A single plane oriented sensor which produces an omnidirectional signal.
>
> A hovering mass like the globes you can buy
> suspended within a magnetic field
>
> ****Don't know- who makes them ?
>
> A gyroscope of light where you measure phase differences between input 
> and output
> A laser beam traveling through a fiber optic coil.
>
> ****These may be a bit temperature sensitive and require fairly expensive
> optical components.
>
> A foam pad which changes resistance with compression
> so you just put a mass like a gallon of water on it
> to measure vertical forces
>
> ???
>
> Isn't there something novel and cheap and easy to try ???
>
> ****Yes. 44mm OD Piezo Sounder Disks and a weight. I use about 1 oz.
>
>     Regards,
>
>     Chris Chapman

LOL, yes but looking at your design it takes a mechanical
engineer to put it together,

I would need a kit ready to build or one already prebuilt.

But with the economy like it is today, My fun days might be over.

I often thought an inverted pendulum with a couple of
pizo thingys flexing at the bottom in like a bridge affair
might do the job.

Even tho I cant play much anymore I will watch
as much as I can whats going on.

I cant wait to see what kind of seismometer
they eventually send to planets in the
solar system with gravity less than our own.

I think the one they sent to the moon was
quite conventional with a type of pendulum.
But can you imagine how much it cost
to build and get it there.

The moons seismicity is interesting to read about.
They even have seismic signatures of meteor strikes
on the moon.

Happy New Year 2013,
geoff

  
    
  
  
    
On 12/31/2012 6:40 PM, chrisatupw@....... wrote:
From: Geoff <gmvoeth@...........>
To: psnlist <psnlist@..............>
Sent: Sun, 30 Dec 2012 23:14
Subject: Re: Instrumentation Question

There must be some kind of strain gauge where you simply hang a weight like a pendulum
and any swing however slight would create a signal.

****Strain gauges give quite a low sensitivity.

Then the signal would be omnidirectional which is what I am looking for.

A single plane oriented sensor which produces an omnidirectional signal.

A hovering mass like the globes you can buy
suspended within a magnetic field

****Don't know - who makes them ?

A gyroscope of light where you measure phase differences between input and output
A laser beam traveling through a fiber optic coil.

****These may be a bit temperature sensitive and require fairly expensive
optical components.


A foam pad which changes resistance with compression
so you just put a mass like a gallon of water on it
to measure vertical forces

???

Isn't there something novel and cheap and easy to try ???

****Yes. 44mm OD Piezo Sounder Disks and a weight. I use about 1 oz.

    Regards,

    Chris Chapman

LOL, yes but looking at your design it takes a mechanical
engineer to put it together,

I would need a kit ready to build or one already prebuilt.

But with the economy like it is today, My fun days might be over.

I often thought an inverted pendulum with a couple of
pizo thingys flexing at the bottom in like a bridge affair
might do the job.

Even tho I cant play much anymore I will watch
as much as I can whats going on.

I cant wait to see what kind of seismometer
they eventually send to planets in the
solar system with gravity less than our own.

I think the one they sent to the moon was
quite conventional with a type of pendulum.
But can you imagine how much it cost
to build and get it there.

The moons seismicity is interesting to read about.
They even have seismic signatures of meteor strikes
on the moon.

Happy New Year 2013,
geoff

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