[rescue] Oh no! This poor Origin server.....
alaric at caerllewys.net
Thu Apr 1 21:48:06 CST 2004
On Thu, Apr 01, 2004 at 10:43:36PM -0500, Dave McGuire wrote:
> 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.
Hmm. I believe I understand how that would work. Cool.
> 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.
And a solid-state relay instead of the DPDT switch? (Faster switching
> Here are some links:
Cool. Danke. :)
(Of course, I still have no idea what I'd use one for. I mean, I know
what it DOES, I just don't know what I'd DO with one.....)
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