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Offline avision4u2liveby
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« Reply #10 on: August 24, 2011, 04:27:20 pm »
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just chuckling here, I'll wait and complicate GD's answer later.... bwah ha ha ha  Hello

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« Reply #11 on: August 24, 2011, 04:42:19 pm »
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Quote:Posted by gambol1
GD, Lets see if I've got this right. My not PI F75 is detecting the induced eddy currents in the object after the xmitter is turned off or while it is on? And a more intense field transmitted into the ground will not necessarily improve the detector's ability to see the target because of loss in the detector circuit and coil?. If that is the case how do the 2 box units see deeper? gambol


GD will answer this I'm sure but here I go.

Your F75 works on the VLF principal of detection.

The Transmit is continuous.   Does not shut down as in a PI.

The Receive section of your detector continuously gets a receive signal.

A target causes a Phase Shift of that signal.     This is how they detect.

The field intensity of the larger coils can see deeper then the smaller coils, BUT   the Field intensity of the Smaller coil in stronger and can see smaller targets.



The same applies to the two box detector.

As the Transmitter is located away from the Receiver, the singal is projected over a larger area but become quite low in INTESITY.

Received Return signal INTESITY is quite low.

Yes like a larger Coil they will go deeper but your not going to find many targets under the size of a 4lb cannon ball.  LOL


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Offline GoldDigger1950
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« Reply #12 on: August 25, 2011, 04:14:35 am »
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Quote:Posted by gambol1
GD, Lets see if I've got this right. My not PI F75 is detecting the induced eddy currents in the object after the xmitter is turned off or while it is on? And a more intense field transmitted into the ground will not necessarily improve the detector's ability to see the target because of loss in the detector circuit and coil?. If that is the case how do the 2 box units see deeper? gambol

That's correct. As has been stated by Homefire, the two box units work differently.

The single coil ordinary detectors have the Tx and Rx coils right next to each other. If you left the Tx coil on all the time, it would block any chance of an induced field being detected by the Rx. Thus, the Tx coil must be turned off for the Rx cycle time. In the two box units, the two boxes and coils set up a continuous field between the two units that can detect anything metal that comes between the two units.

Those who try to increase the power beyond the limits of physics are wasting their time. But if they are amused, I say go for it.

I predict that the next technology in deep seeking will be in ultrasonic chirping transmitters using using multifield receiver antennas - not at all like current coils. The chirping transmitters will use very dense steel and ceramic elements and the receivers will use multifilar wound flat coils in a funnel shaped array.

Posted on: August 25, 2011, 12:13:52 PM
Quote:Posted by avision4u2liveby
just chuckling here, I'll wait and complicate GD's answer later.... bwah ha ha ha  Hello

I just beat you to it, mate.

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Offline avision4u2liveby
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« Reply #13 on: August 25, 2011, 11:48:25 am »
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Great answer! After reading up and studying how different  detectors work......(something the author of this thread should do) that is exactly whats happening in your detector. Thats also why I like the newer VLF units because they process the info very fast and acurately, and have discriminate (unlike a PI unit, read up on PI detectors before you piss off GD with a question about that lol) Thanks GD, and Homefire! I'm always impressed with your knowledge and experience here.   Wise

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« Reply #14 on: August 30, 2011, 08:59:13 am »
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gd,

" ultrasonic chirping transmitters using using multifield receiver antennas - not at all like current coils. The chirping transmitters will use very dense steel and ceramic elements and the receivers will use multifilar wound flat coils in a funnel shaped array."   I've been waiting for a use for this.  Funny


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Offline Homefire
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« Reply #15 on: August 30, 2011, 09:13:55 am »
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Trouble with Ultra Sonic is it generally requires Contact of the Substrate.   It would be a Contact , Drag type coil.Huh??

Ultrasonic have been used in many applications that could work.

All Require Contact with the object/suspect of material.

If it could be Modulated with some other Carrier it could work.   

My Neighbor plays his Wrap Crap 2/10th of a mile away with enough power to  rattle my doors and windows.  LOL

That may be a Option.







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« Reply #16 on: August 31, 2011, 02:47:27 am »
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Homefire, I've seen advertisements for ultrasonic ground imaging devices. I don't know how well they work though.
One of my crazy experiments was a sonic probe for detecting arrowheads in loose sand. It was nothing more than a 3/16 SS probe with a microphone attached to it. the mike fed a mini tape recorder with headphones which acted as an amplifier. The principle is that when you use a probe you recognize the sound it makes when it strikes an underground objects. Its an old princlple that has been used for collectors for years.  Arrowheads make a click sound. bits of limestone make a more dull sound, roots make a thump. The idea of the microphone was to hear the sound better. Unfortunately,  The amplified sound was different than the one you hear directly and therefore, eventhough it was louder, It masked differences rather than improved the finding. I did learn some things from the experiment though. The shape and material of the rod is all important. the harder the steel the louder the click.  They rod should be less than half the diameter of the object. 3/16 to 1/4" is about right for arrowheads. The handle should be of metal not wood. Wood dampens the sound. I will try this experiment again some day if I get a smaller microphone that will fit inside a hollow probe at the tip and a better quality amplifier. gambol.

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Offline Homefire
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« Reply #17 on: August 31, 2011, 08:03:53 am »
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Cool Stuff.     I have a idea for a probe for you.    Let me draw it up and post in a while.

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« Reply #18 on: September 01, 2011, 04:55:15 am »
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I'd like to see that.

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http://search.yahoo.com/r/_ylt=A0oG7hGJXl9OVXIAHgBXNyoA;_ylu=X3oDMTBybnZlZnRlBHNlYwNzcgRwb3MDMQRjb2xvA2FjMgR2dGlkAw--/SIG=13hhu78e9/EXP=1314901769/
**http%3a//www.cee.ucla.edu/news/spotlight-archive/ultrasonic-imaging-of-objects-embedded-in-soil

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Offline denizenTopic starter
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none at the moment, but soon a TGSL i will build
« Reply #19 on: September 02, 2011, 08:06:40 am »
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Could I use something like

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http://www.amazon.com/Eveready-Battery-Batteries-Remote-Control/dp/B000BQUUGC
this, a small 12 V battery? It would conserve space (which is my main goal in this build). I'm not too concerned about battery life. I'm concerned if the amperage is too far from 8 AAs to cause damage/poor power to the electronics.

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