The BigFoot Search Coil
Engineer: Jim Karbowski "The Wizard of Loop"
Author: Greg Moscini
Trans Bay Metal Detectors
321 Sea Horse Court
Foster City, CA. 94404-1936
Business : 650-574-2012
Voice Pager: 650-684-9888
Big isn’t everything, especially when it comes to search coil size, BUT when it happens to represent the latest innovation development of the Wizard of Loop, Jim Karbowski, of Applied Creativity, it translates into a MAJOR breakthrough in terms of coil design and performance.
This unique search coil, appropriately called BigFoot (Design Pat. Pend), by virtue of its measurements; 18" Long by 3 ½" wide. What makes this coil so unique and innovative? Unbelievable as it is, the BigFoot does not "see" ground mineral (homogenous), wet salt or black sand. BigFoot will cancel out the ground effect BEFORE it reaches the detector circuits. Amazingly enough, it is virtually unaffected by 60 cycle interference If these features don’t get your attention, how about BigFoot weight: Actually less than most standard 8" search coils.
Heard enough? Well that’s not all, BigFoot pin points the target in the center of the coil, NOT by an AUDIO INCREASE as is standard with all industry coils, as you scan over the target center, but by a SHARP NULL (Dip in the threshold to quiet). Yet another plus is that since it is 3 ½" wide, it has outstanding abilities to isolate a good target side to side, which would normally be masked by a bad target due to close proximity.
Most conventional coils whose magnetic field tends to be conical, narrowing to a point at the fringe area, thus demanding significant overlapping to ensure one does not miss those 6+ inch targets. BigFoot’s magnetic field throws a vertical sheet into the ground, much the same shape as the bottom keel of a ship, so there is no need to overlap, thus one can search LARGE areas such as ballfields, parks, beach and desert with GREATER area coverage and efficiency.
For the purposes of my field test, I chose Whites 1987 Eagle with the new Eagle II chip update. Normally, with the standard Whites 8" coil, I can turn the AC (overall systems) Discrimination Sensitivity from 2 to 4 in my front yard before the 60 cycle electrical lines running under the ground, start to take their toll on the stability of this detector. With BigFoot connected, 60-cycle interference all but disappeared up to level 6 on the sensitivity.
Prospecting?: You might be asking yourself, would a coil that size be effective in locating larger nuggets in mineralized ground? One of the areas Jim Karbowski had in mind, when he developed his "dream" coil was Australia where the ground is mineralized and nasty, but the nuggets are oh so big. Does this mean that BigFoot will overlook those elusive tiny nuggets?…. Don’t bet on it. BigFoot will respond on nuggets down to a grain in size! For those sub-grain nuggets, the Whites Black Max 5.3 and 350 would be a better choice.
BigFoot is designed to be swept much like a windshield wiper works on your vehicle's windshield. I found that I could actually walk in an almost natural gait due to the large amount of ground coverage with every sweep. One IMPORTANT thing to remember is sweeping BigFoot, to keep the bottom of the coil as level as possible for best ground elimination results BigFoot is fully hot over the entire 18" length while operated in the Discrimination Mode. In the all-metal mode it is hot over the first 9" with one exception.....During the final development stages of BigFoot, Jim Karbowski consulted with one of Whites top engineers, was responsible for the development of the Eagle. Whites first microprocessor detector. Rick was so impressed with BigFoot concept, he developed a BigFoot mode in the new Eagle Chip which when activated will make BigFoot hot over the entire 18" length while in the ALL METAL mode. This will be an added boon to relic hunter and those tha t prefer hunting in the all-metal mode under certain field applications.
FIELD COMMENTS AND REPORTS FROM THE PROS
It was Friday morning and an excellent time to visit the local beach. The April weather was beautiful and spring had indeed come early to the Bay Area. I arrived at the beach in the early morning before the anticipated droves of people would start to show up. Fortunately the tide was going out leaving me a large area to hunt. This particular beach is an inland beach and radio abounds. It is in the vicinity of San Francisco International Airport and under the path of arriving flights.
Several detectors I have used at this particular beach have not fared well due to factors of mineralization, abundance of iron and radio frequency interference, which had forced me to minimize the detectors' sensitivity in order to achieve a workable stability. The trade off is generally a loss of deeper coins/targets.
I opted to run the Eagle with BigFoot in the Hip Mount Configuration using the Jimmy Sierra Hip Mt. which uses the popular 'S' Handle design which I much prefer because of comfort, over the straight handle configuration. (note: Due to the advent of the new SL configuration, a hip mount kit is no longer preferred).
With a press of the power pad, the Eagle came to life. With two taps of the [AUDIO] Disc pad, the Eagle was now in the BEACH MODE (Mode C) with a Default Sensitivity setting of 4 AC/Disc). At this level the BigFoot was stable as a rock with absolutely NO hint of radio interference. I was curious as to how it would react to higher levels of sensitivity so I then placed the BigFoot flat on the ground and proceeded to increase the Eagle’s AC sensitivity to the maximum level of 7 WITHOUT any reaction from radio interference.
I then began a systematic method of hunting perpendicular to the beach while dragging a 40" long handle sand scoop thus marking off a grid to insure that I avoided detecting over the same area twice. With the sensitivity set back at the default 4 level, the combination BigFoot and Whites Eagle II Electronics resulted in exceptional stability and almost perfect operation.
Utilizing the narrow width of BigFoot (3 1/2 inches) I was able to locate good targets hiding between numerous iron targets which might have been lost using a standard coil. I found that iron targets would at times give a VERY minimal edge effect/chatter depending upon the size of the iron, depth and proximity to other targets. HOWEVER, generally speaking, BigFoot’s rejection of Iron junk was cleaner than any coil I have yet to use on the Whites GEB Discrimination Detectors.
I picked up most of my desirable targets between surface to 6 inches and wasn't fooled by any Iron targets with the exception of a boarder line response and in my eager haste, up came a rusty bottle cap (the first and last for the day). The area I covered would have normally taken me about 2 1/2 hours. With BigFoot BigFoot, I started at 9AM and finished at 10:30 AM. The savings of almost an hour due to the 18" Sweep Path is typical of the efficiency of area coverage you can expect with this incredible coil.
PINPOINTING with BigFoot I found to be just plain neat.....while a conventional coil will pin point the target by increasing sound or pitch which can be at times annoying and hard on the ears, BigFoot pin points with a NULL which is a very definite break off of the threshold. This UNIQUE method of pin pointing eliminates the need for having to DETUNE the target when using a conventional coil. When you change to the all metal mode to pin point, the bottom half of BigFoot actually goes null so you must make sure that your over the target with the first 9"s of coil. The actual depth reading of the target is achieved in the middle of that positive section of 9". By pushing BigFoot forward the threshold drops off rapidly and abruptly NULLS or goes silent. That’s when you’re DIRECTLY over your target.
Several days ago, Rich Green of Professional Recover Tools (ala Hole Hog/Pouch) called me to update me on his experience in the field with BigFoot. Rich was very excited about the BigFoot’s field performance. He and Mike Brighty of Whites of the Great Lakes (Toledo, Ohio) went out to one of their favorite Civil War sites in Kentucky. In the past Rich had complained of a large area directly under double pole Electrical Lines which were approx. 60 feet in height. The interference was so bad that NONE of the detectors would function in close proximity to these power lines. In Rich's words, several different detectors he had tried were "Shut Down" when he attempted to hunt anywhere near them. Rich was enthusiastically happy to give a positive report on BigFoot which he said " Ignored the power lines like they weren't even there." Mike Brighty was able to detect directly under the power lines and up a small slope within fifteen feet of them with out any adverse effect on his Whit es Detector. He located a nice U.S. Oval Belt Buckle, 35 Mini Balls, a Sword Carrier, and Scabbard tip.
The BigFoot is will work on the Whites Pro Series, Eagle, Spectrum, and XLT. The BigFoot will work but in a slightly different way on the Quantum II and XT, but the back 9" of the 18" overall length, responds with a overshoot noise rather than the standard audio response of the front end. It is the most exciting search coil design I have ever had the pleasure of hunting with, and is my first choice as an accessory loop to the 950 and Royal 800. You might say that the BigFoot 'Will go where no other coil has dared to go as well as ABLE to cover a full 18" in a single sweep..... BigFoot is indeed the SUPER COIL of the 1980's and 90’s into the year 2000.
Note: Greg Moscini is the owner of Trans Bay Metal Detectors, a multi line detector dealer located at 321 Sea Horse Ct. Foster City, Calif. 94404 650-574-2012. Feel Free to ask Greg any additional questions either by Email; firstname.lastname@example.org, phone or self-addressed stamped envelope.
Rich Green is the owner of Professional Recover Tools, 416 Kelly Drive, Brownstown, IN 47220 812-358-4999. Mike Brighty is the owner of Whites of the Great Lakes located in Toledo, Ohio. Note: The BigFoot article was originally written in 1987, so some of the phone numbers and addresses may have changed.
The BigFoot loop can be purchased through authorized Whites Dealers. For further information, call Whites of California, 800-457-0875 for the local stocking dealer nearest to you.
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Revised: May 26, 1999 by Greg Moscini, Trans Bay Metal Detectors
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