[rescue] Oh no! This poor Origin server.....

[Dave McGuire]

On Apr 1, 2004, at 10:19 PM, Joshua Boyd wrote:
>>>> because I have an interest in proton-precession magnetometry and
>>>> gradiometry.  Someday I hope to have that much free time.
>>>
>>> I, in my insignificance, bow before the radiance of your magnificent
>>> |bergeekdom.  :)  I wouldn't know a proton-precession magnetometer if
>>> it leaped out from behind a field of monopoles and bit me in the ass.
>>
>>   Uhh, what?
>>
>>   Dude, they are *really* simple.  You could build one in an evening.
>> Seriously.
>
> How?

   Uhh, I'm not going to type up huge amounts of detail, but here's the 
basic idea:

   Go to Home Depot (or equiv.) and get a 9-12" section of 3 or 4" 
diameter PVC pipe and some end caps.  Fasten one end, fill it with 
kerosene, then fasten the other end.  Be sure to get a good seal.  Wrap 
a few dozen turns of fairly thick (~14ga) wire around it.

   Build an amplifier and a bandpass filter centered around 2.46KHz.  
Get a large-ish 12V battery (like a lantern battery) and a beefy DPDT 
toggle switch.  Wire up the bandpass filter/amp combo, the coil around 
the kerosene cell, and the battery in such a way that the coil can be 
alternately switched between the battery and the filter/amp combo.  
Connect the output of the amp to a speaker or a set of headphones, as 
well as a frequency counter.

   Voila.  A proton-precession magnetometer.

   Of course, myself, I would do it with some big MOSFETs, a 
microcontroller (no, not some monster with an MMU and an operating 
system, Josh. ;)), and an LCD.

   Here are some links:
   http://www.portup.com/~dfount/proton.htm
   http://members.aol.com/alka1/ProMag.html

        -Dave

--
Dave McGuire          "PC users only know two 'solutions'...
Cape Coral, FL          reboot and upgrade."    -Jonathan Patschke