PSN-L Email List Message

Subject: Re: Questions from a beginner
From: ChrisAtUpw@.......
Date: Wed, 2 Aug 2000 17:24:19 EDT

In a message dated 02/08/00 17:10:53 GMT Daylight Time, lconklin@............ 

> My most important move was away from the driveway.  Up till that
> point I had a Toyota detector.


    This suggests that you probably ARE picking up magnetic interference. On 
your SG rig, you have a powerful bar magnet part way down the pendulum, don't 
you? This can react to any changes in the local magnetic field. Might it be a 
good idea to check if any of your noise signals are associated with any 
domestic appliances?    

    As a rough guide, a 1/4 x !/4 x 1 inch Alnico magnets as used for reed 
switches produced 50 nT at 53" and a smaller 4.5 x 4.5 x 28 mm magnet give a 
similar field at 45". This is about the change you see on the Earth's field 
on a 'quiet' day. Magnetic storms can give over 10x this. 



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Larry Cochrane <cochrane@..............>