PSN-L Email List Message

Subject: Re: Fwd: Loudspeader Seismograph re: the Elektor magnetometer article
From: "Geoffrey" gmvoeth@...........
Date: Sat, 28 Apr 2007 00:03:50 -0700


Why Doesnt anyone ever talk Hall-Effect or Strain Guage or Variable Resistance or magnetic levitation like you take up most the 
strain with a spring but levitate grain or so with an electro magnet to counter gravity and set the period ??
You can use some kind of PID (Proportional Integral Derivative) Like the cruise control of an automobile to set the operational 
point ??
If I had cash I would try some of these but you need to have a PHD in Physics to get a Government Grant.

----- Original Message ----- 
From: "Charles R. Patton" 
To: 
Sent: Friday, April 27, 2007 12:07
Subject: Re: Fwd: Loudspeader Seismograph re: the Elektor magnetometer article


> Don't waste your money on this article.  It is done using a coil salvaged from a transformer fed to an amplifier with lots of 
> gain.  Strictly AC, no DC response possible.   I consider the definition of "magnetometer"  requires DC response. Misleading 
> advertising. As additional criticism, using a small coil salvaged from a transformer has very little window area (limiting the 
> "effective antenna height" acting as another limit) if you intend to receive ELF.   Bah, humbug, $2 wasted.
> Charles Patton
>>> Hi, The "May 2007" issue of "elektor electronics"
>>> magazine, contains an article using a loudspeaker
>>> as a vibration sensor (seismograph). Plus an article
>>> on ELF reception and a magnetometer.
>>>
>>> www.elektor-electronics.co.uk
>>>
>>>
>>> May be of interest ?
>>>
>>>
>>> Cheers Arie
>>>
>>>
>>>
>>>
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>>
>>
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>
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>
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>
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