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  #26  
Old 04-26-2012, 02:37 PM
goldfinder goldfinder is offline
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Default What frequency?

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Originally Posted by humhum View Post
Hi Erevnitis, I make test with my LRL before one year and it be very sensitive of Aluminum ( like your PD) from 100m . Why ? I not understand.
May be that not have classificator for gold. What you think?
If you are using a frequency in your LRLs what is that frequency? If not a frequency is there filters in your circuitry? It their resonance is not correct your unit may be picking up signals from other metals like the aluminum.
Goldfinder
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  #27  
Old 04-26-2012, 05:15 PM
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humhum humhum is offline
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Quote:
Originally Posted by goldfinder View Post
If you are using a frequency in your LRLs what is that frequency? If not a frequency is there filters in your circuitry? It their resonance is not correct your unit may be picking up signals from other metals like the aluminum.
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I use filters for 50Hz.
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  #28  
Old 04-26-2012, 06:31 PM
Dave J. Dave J. is offline
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Default geographic region makes a difference

Simple twin-T notch filter tuned for 60 Hz will knock out most aluminum and copper interference in the Americas. Oddly enough these materials seem to know where they're located and in most of the rest of the world their frequency is 50 Hz. For use worldwide, just cascade a 60 Hz notch with a 50 Hz notch and ya got it covered.

The original Fisher Gold Bug (approx. 1986) had a 60 Hz notch filter for knocking out those pesky aluminum and copper signals. The system was set up to nonetheless be able to detect a full can of beer, since ya wouldn't want to pass that up. Unfortunately we weren't able to keep it from detecting empty beer cans as well, even just a few drops of dried beer residue was enough to fool it. But that was the all-analog olden days. Nowadays we're working on a software app to solve the problem.

--Dave J.
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  #29  
Old 04-26-2012, 10:40 PM
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Qiaozhi Qiaozhi is offline
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Quote:
Originally Posted by Dave J. View Post
Unfortunately we weren't able to keep it from detecting empty beer cans as well, even just a few drops of dried beer residue was enough to fool it. But that was the all-analog olden days. Nowadays we're working on a software app to solve the problem.

--Dave J.
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  #30  
Old 04-27-2012, 07:19 AM
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humhum humhum is offline
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Quote:
Originally Posted by Dave J. View Post
Simple twin-T notch filter tuned for 60 Hz will knock out most aluminum and copper interference in the Americas. Oddly enough these materials seem to know where they're located and in most of the rest of the world their frequency is 50 Hz. For use worldwide, just cascade a 60 Hz notch with a 50 Hz notch and ya got it covered.

The original Fisher Gold Bug (approx. 1986) had a 60 Hz notch filter for knocking out those pesky aluminum and copper signals. The system was set up to nonetheless be able to detect a full can of beer, since ya wouldn't want to pass that up. Unfortunately we weren't able to keep it from detecting empty beer cans as well, even just a few drops of dried beer residue was enough to fool it. But that was the all-analog olden days. Nowadays we're working on a software app to solve the problem.

--Dave J.
My Filter is for Reject of 50Hz, and sensibility of other all frequency.

http://www.geotech1.com/forums/showthread.php?t=14475
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  #31  
Old 04-28-2012, 02:50 AM
goldfinder goldfinder is offline
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Default 50m Khz may be Au freq

In my analysis of gravitational resonances 50 Khz popped up as one of the possible for gold. Also, if the dowsing and MFD bunch are to be believed, 5 Khz is another Au frequency which is a 1/10th subharmonic of50 Khz.

If 60 Khz is the aluminum frequency range you might consider changing your filter to that and make sure the bandwidth of your notch filter isn't so wide it also excludes 50 Khz.
Goldfinder
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  #32  
Old 04-28-2012, 04:15 AM
Dave J. Dave J. is offline
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You're confusing Hz with kHz. Aluminum and copper frequency is 50 or 60 Hz depending on your geographic region. Major gold frequency is 19.2 kHz, but that's a geographic variable, too. Rumor has it that Africa is a hot spot for 13 kHz and 48 kHz, maybe Carl's heard the same rumor.

As I explained in a prior post, the peculiarities of specific targets can throw off frequency calculations. For example cans that contain or have contained beer also "hit" at 19.2 kHz, maybe it's the golden color that skews it. Brown beers come in bottles, not cans, so I guess we'll never be able to test the "color skews it" theory. ......Hmmm.....I haven't seen Rainier Ale ("green death") in at least 20 years, don't think they make it any more. But back in the 1950's Pearl Bailey sang the radio ad that it really made her canary sing (great ad!), maybe the residue of green beer in a green can would make a metal detector beep? But wait, canaries are yellow, so is gold? This stuff is 'way too mysterious for the mortal mind to fathom! Maybe mortals should stick to simple stuff like theology or how to eat spaghetti.

--Dave J.
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  #33  
Old 05-02-2012, 12:38 AM
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Erevnitis Erevnitis is offline
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Quote:
Originally Posted by aft_72005 View Post
Hi Erevnitis
I saw your webpage , your LRL boxes is very nice with elegance , and one thing interesting me,
You use IR transmitter type LED in your most project .
Please explain how it works??
The IR led and lens is good but the ultraviolet better
aft_72005 where are you from?

The target finally is an aluminum alloy part from second international war,and there is continuity below of this small target.

Thank's that you share with me this story,if i have any new I'll put some new related video.

Regards:

Erevnitis
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  #34  
Old 05-02-2012, 03:28 AM
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aft_72005 aft_72005 is offline
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Quote:
Originally Posted by Erevnitis View Post
The IR led and lens is good but the ultraviolet better
aft_72005 where are you from?

The target finally is an aluminum alloy part from second international war,and there is continuity below of this small target.

Thank's that you share with me this story,if i have any new I'll put some new related video.

Regards:

Erevnitis
Hi Erevnitis
Thanks for your information but my opinion was how IR act as long range detector?,
How IR help to other part of long range detector ? how IR LRL work ?
I am from Asia.
Regards.
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