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Offline cdalake1Topic starter
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« on: December 27, 2010, 01:59:12 pm »
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Hi, I'm new to thunting.com.  My dad and I have built Gary's PI-1 detector and are wondering what experiences others have had using this detector for gold prospecting.  Does it have issues with interference or ground signals, loop designs that have worked, etc... 

Any help will be greatly appreciated, Thank You

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Offline Homefire
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« Reply #1 on: December 27, 2010, 02:06:15 pm »
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Shield the coil and get the Sample Rate under 17us and it can do the job.

It's a good detector.

Have you tried his Spider coil?

Next best would be a Etched spiral.



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Offline cdalake1Topic starter
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« Reply #2 on: December 27, 2010, 02:33:11 pm »
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Homefire, thanks for the quick reply, I've read mentions of shielding the coils but haven't seen a good description.  How is it accomplished? 

Posted on: December 27, 2010, 02:30:10 PM
Ooops, forgot to answer your other questions about the coils we've tried.  We've wound one spiral coil just to test the detector, it measues 345 uH and seems to work well, so we are now researching coil designs for actual field use.   

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Offline DonAu
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« Reply #3 on: December 28, 2010, 10:56:12 am »
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 Hello cdaLake1,

I'm interested in PI detectors and at present am trying to find info on the relationship of loop size and detection depth ie is there a practical size maximum?

DonAu

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Offline GoldDigger1950
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« Reply #4 on: December 28, 2010, 11:48:03 am »
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Quote:Posted by DonAu
Hello cdaLake1,

I'm interested in PI detectors and at present am trying to find info on the relationship of loop size and detection depth ie is there a practical size maximum?

DonAu

The size of a coil can increase only to when it can be a multiple wire. A single wire has no inductance that is measurable.

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It's all about that moment when metal that hasn't seen the light of day for generations frees itself from the soil and presents itself to me.
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« Reply #5 on: December 28, 2010, 12:54:23 pm »
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Quote:Posted by cdalake1
Homefire, thanks for the quick reply, I've read mentions of shielding the coils but haven't seen a good description.  How is it accomplished? 

Posted on: December 27, 2010, 02:30:10 PM
Ooops, forgot to answer your other questions about the coils we've tried.  We've wound one spiral coil just to test the detector, it measues 345 uH and seems to work well, so we are now researching coil designs for actual field use.   
3m makes a shielding tape that works well.  Conductive paints,  Good ol Foil.



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Offline cdalake1Topic starter
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« Reply #6 on: December 28, 2010, 02:23:12 pm »
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Thanks for the info, where is the loop shield installed?  I'm assuming on the top side of the loop and then connected to ground, is this correct or are we talking about shielding the loop wires between the detector and the loop or both? 
We are planning to use shielded wire between the detector and the loop, any recommendation for this, I've read about using coaxial cable or shielded twisted pair. 

Cdalake1

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« Reply #7 on: January 22, 2011, 09:39:32 am »
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Greetings, I had difficulty with the cable between the coil and the detector, we solved the problem using cat-tv 180cm and another version, we dissected a cord from a CRT monitor and I used one of the three RGB cables with good results.
 And I have a question, if the shielding coil, detection sensitivity is not lost? and shild where it connects? to  minus battery or ground circuit?

Sorry if phonetic mistakes ....



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Offline GoldDigger1950
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« Reply #8 on: January 26, 2011, 05:01:55 am »
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The shield should connect to ground. The shielding will improve the sensitivity.

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It's all about that moment when metal that hasn't seen the light of day for generations frees itself from the soil and presents itself to me.
Let's Talk Treasure!
Offline cdalake1Topic starter
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« Reply #9 on: January 27, 2011, 11:20:47 am »
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I found a good article on making a fast loop with shielding for gold detection at the link below.  It discusses the importance of minimizing the capacitance the the loop and connecting cable along with different sheilding materials and the effect on sensitivity.   Some good proven ideas are outlined.

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http://www.geotech1.com/pages/metdet/projects/fastcoils/FastCoil.pdf



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