Bottle cap test :usaa:for Jim [Humble Pie]:detecting:

[vlad]

I took the cap that read 90 on my F-75 and buried it 4 inches- it still reads 90, and DE mode and Delta Pitch give best reject capabilities. Ran disc as high as 30 [ no change in i.d,]; in DE mode audio gives a [best]"warble"[in audio of DP] that sounds very different from a conductive target.
Tried the following machines against it:
Treasure Baron; read pull tab but with lots of iron grunt & silence, especially going past the cap, either up or down or sideways. [Iron notched out]
Garrett Gti-2000; bounced all over the top end from penny to dollar down to iron with iron grunt & silence. [iron notched out]
Cz-70Pro; read consistent pull tab over center but bounced when near the edge of the loop and gave iron grunt/silence. [0 disc]
C$ signal bounced all over the place & no consistent lock-nearest repeatable number was pulltab. Lots of iron grunt signals. [full iron out]
All of these other detectors had concentric loops vs the DD on the F-75 so you can draw your own conclusions.
Would love for someone to run similar test with small concentric.
AND FISHER PLEASE GET THE 10" CONCENTIC OUT!!!!!!!!!!!!!!!1

 

[HumblePie]

Thanks a million Tim, it looks like the DE mode with Delta Pitch works well for bottlecap identification. As you've pointed out before, using the edge/heel of the coil is also a good technique for distinguishing these pesky bottlecaps.
The fact that it indicates a reading of 90 is a bit of a tip-off too, insofar as how many silver dollar type coins do we ever come across. I suspect with a little familiarity with this unit's response to silver quarters, half dollars and dollars in terms of the tone, we would soon learn to hear the difference between these targets and bottlecaps as well. Hopefully, the concentric coil will provide better discrimination ability.
Incidently, when you did the test, did you notice how the confidence meter read over the bottlecap? Appreciate you making this effort...Jim.

 

[Chris(SoCenWI)]

Vlad,

I've posted for advice about bottlecaps on this forum a couple times and the best offered is just dig them- impossible to accurately differentiate. I've tried all the hints about confidence meter and FO2 graph and different sounds. Found nothing is close to 100%, just when I'm sure I'm going to dig another bottle cap I get a coin, often silver. It is very frustrating to me because my only other machine, the explorer doesn't have this problem, bottle caps hit way lower right, nothing else does so they are never a problem with this machine. I've heard from others that many machines have the same problem, I just never experienced myself until I tried the F-75. And not just bottle caps, any flat chunk of iron will act much the same.

I also bought the smaller coil this winter, the day before yesterday did some testing. I also saw that if I laid my digging screwdriver on the ground I would not get a hit on a coin unless it was more than 8" away. Someone had mentioned this with rail road spikes earlier.

I tried laying a nail on top of coin. With the DD coil on the XS I can get a good coin hit when the center of the coil is parallel with the nail. Not perfect but hits upper middle, which I always dig. At any other angle gives an iron hit. The F-75 behaved pretty much the same, gave a hit at only one angle, iron the other. The smaller coil behaved the same which I was not expecting as it isn't a DD. Problem was the hit from the parallel angle still averaged the reading down to 30 or so, Tab/nickel range. Probably would not dig such a signal.

Also tried laying coin 1-3" from nail, at a fast swing would get iron if swung from nail side, averaged lower hit from the coin side. If I slowed way down got two distinct hits. If I wiggled the coil over the coin I would get a pretty accurate reading. Gut feeling that faster processor doesn't help in trash that much.


Chris

 

[GraveDiggerMax-VaBch-Va]

when i get home in the afternoons, u know where i live, the dry sand is bottle cap heaven and the F75 loves those caps so far

i hunted today in bc.................more later

 

[vlad]

Try using the outside loop edge technique; get the loop edge near the target then move past. As the target cap goes beyond the edge it grunts every time in my ground.
How does the 6" concentric perform on caps?

 

[Chris(SoCenWI)]

n/t

 

[vlad]

I had it accepting iron and disc control fully clockwise. So I repeated the test with iron notched out and the disc. control fully c.c.
It read iron and stayed silent on that same buried cap swept from every direction-every time.
GEORGE PAINE, still KING.

 

[Cal_Cobra]

[quote vlad]
C$ signal bounced all over the place & no consistent lock-nearest repeatable number was pulltab. Lots of iron grunt signals. [full iron out]
:[/quote]

Interesting testing...what is the C$ "iron grunt" signal ? You were running iron at 99 ?