Ferrous tones vs Conductivity

[Tagamet]

I see/read that a lot of people prefer to hunt in ferrous tones as opposed to conductivity. To a returning newbie, it "feels" like having a high tone based on conductivity would be intuitively better than a tone based on what I'm trying to aviod (iron).
Can someone please try to help me wrap my tiny mind around the advantages of hunting in ferrous tones?
TIA,
Tagamet

 

[Cody]

Some iron and alloys are highly conductive so will give a high tone when hunting in conductive/size tones. Ferrous tones is based on ferrous content and will give a low tone on high and low conductive iron. This makes it easier to hunt at a site that has a lot of iron.

I think this is the most common reason.

 

[Captain Kirk]

Tagamet

Perhaps the best way to learn the advantages of the FERROUS mode is to run an experiment. In the FERROUS mode, run a dime past the coil and then run a nail past the coil. You will then see how easy it is to avoid nails using the Ferrous mode.

One down side about FERROUS mode is that some deep silver coins coins will hit rather far to the left side of the screen and produce a rather low tone (This depends upon ground mineralization and nearby trash). It could be easy to miss these if you are not on your toes.

HH,
Glenn

 

[Cody]

I assume those coins will sound high in conductive? I had not realized that and have heard some low faint tones that I thought were a default for targets too deep to ID. That is interesting but you are sure correct about nails as I have no problem with them in Ferrous.

 

[Tagamet]

[quote Cody]Some iron and alloys are highly conductive so will give a high tone when hunting in conductive/size tones. Ferrous tones is based on ferrous content and will give a low tone on high and low conductive iron. This makes it easier to hunt at a site that has a lot of iron.
I think this is the most common reason.[/quote]

Thanks to both responders. Actually, the above reply answers my NEXT uestion, which was "Why the heck am I getting high tones and digging up rusty nails??? (LOL)
Now I know.
Thanks again,
Tagamet

 

[Cody]

A rusty presents a special problem when the detector induces a current into the nail. The currents flow around the nail and down the axis of a nail. Since the detector's ID of targets is based on time constants a nail will have a long time constant. Silver is very conductive, nonmagnetic and the currents flow in a circular path around the coin. Silver has a long time constant so it is difficult for a nail to be identified based on conductivity since it appears to be as conductive as silver.

In ferrous tones if the upper left corner of the display, most ferrous metal with the highest conductivity, is rejected then very few nails should be detected. However, the can be similar to some Indian heads in that the tone will bounce from upper left to upper right. With the upper right clear then a ferrous target that bounces from a rejected area to a clear area will give a high or mid tone depending on how it jumps. This is where switching from Digital or SmartFind to the IM screen at IM-16 will ID the bounce. That is how I use the Iron Mask screen as a backup for Digital or SmartFind. I think that is the idea of unmasking a good targets that is mixed in or appears to be iron. I have recovered some nice Indian heads that will do a nice bounce as described.

Hope this helps,

 

[Charles (Upstate NY)]

Start with the "Getting Started" tip under Explorer Tips on my www.detectorgear.com website, that way I don't have to retype a bunch of stuff. I cover the rusty nails in the bottom half of that tip.

I'll add some thoughts to what I have posted there. This will make more sense if you read the above tips first.

Lets talk about one way signals. In the above tip I recommend new users stick with signals that give a high tone from all angles at first, and save what is commonly labeled one way signals until they have more experience with the machine.

One way signals are those that for example as you sweep a target along a north/south line give you a high tone, but when swept along an east/west line give you a low iron tone. This is a generalization, its best to circle the targe sweeping it from many angles. You may find that you only get a coin tone from one narrow angle.

Not all nails false with a high tone so you are either over a rusty nail that is falsing high or you are over a rusty nail with a coin nearby. How do you tell the difference?

The answer is I consider several factors and take an educated guess. I start with the tone, that will be what got my attention in the first place. Does it sound solid like a coin and fluty? Does it seem small as I sweep across it like a coin will compared to a nail which can seem much larger? As I circle the target sweeping it from different angles does the target stay put or does it seem to changes positions in the ground e.g. I thought I had it pinpointed next to that scrap of paper but now it seems like it moved 3 inches.

Rusty nails tend to move as you sweep them from different directions as they cast signals out along their length. Coins tend to stay put.

Next I look at the bounce pattern of the cursor. A rusty nail that is falsing will bounce from the top left corner of the screen to the far right edge of the screen, with half the cursor off the right edge, and about 1/4 inch down from the top. Coins can bounce also but when they bounce to the coin zone, they tend to hit in their proper location versus off the right edge 1/4 down from the top.

I will say with some confidence that you can rely on the classic rusty nail bounce pattern. If I'm hearing high tones but the cursor is doing the rusty nail bounce, to date all have been rusty nails. If a coin is mixed in with the iron it will generall disrupt this bounce pattern. In extreme cases where the nail is sitting on the coin you might see a mixture of rusty nail bounce pattern with coin bounce pattern. Those are the tough calls. But if all you are getting from the angle of the high tones is the classic rusty nail bounce, keep walking.

Charles

 

[Charles (Upstate NY)]

If you work a rusty nail long enough you can make it sound high from two directions. Usually you are off center of the nail somewhat, catching it with the edge of your coil. It is very important to be centered over the target. Often you generally have to adjust your sweep speed slower as well to get it to false from two directions. I have been guilting of trying to will a rusty nail into a good target on many an occasion with little success so far.

 

[Captain Kirk]

Cody,

I thought for sure you realized that in CONDUCTIVE mode that a silver dime will sound very high, but a nail will sound even higher. It takes some experience to be able to differentiate between the two tones without looking at the screen.

HH,
Glenn

 

[Captain Kirk]

Charles,

I find that a rusty nail on the right or left outer rim of the coil will produce a consistent upper right corner response. When trying to pinpoint in the search mode, then, as you stated, the target seems to move around when you circle the target. That is because you eyes are concentrating on the center spot of the coil. I find that taking 5 seconds in the PINPOINT mode, to made sure that the target is positioned in the center of the coil, makes the final decision much easier.

HH,
Glenn

 

[Cody]

NO, I think I have posted several times that I lost high frequency hearing in Vietnam. There is sort of this odd curve that looks like a hook when hearing is measured in ears with gun shot noise damage. Some of the higher frequencies that most people here with normal hearing I cannot hear at all.

I assume newbies would have problems making the distinctions anyhow so suggest they watch the crosshairs. Other like Charles that can tell one dime from another by sound most likely already know that a nail has a higher pitch. I often see aluminum cans off the screen to the right but do not hear the sound as different than the sound of a coin on the screen.

 

[Dennis 2]

Charles , Great Site . Lot's of good info.

 

[Charles (Upstate NY)]

An enterprising engineer might convert that audio signal into something visual for the hearing impared.

[quote Cody]NO, I think I have posted several times that I lost high frequency hearing in Vietnam. There is sort of this odd curve that looks like a hook when hearing is measured in ears with gun shot noise damage. Some of the higher frequencies that most people here with normal hearing I cannot hear at all.

I assume newbies would have problems making the distinctions anyhow so suggest they watch the crosshairs. Other like Charles that can tell one dime from another by sound most likely already know that a nail has a higher pitch. I often see aluminum cans off the screen to the right but do not hear the sound as different than the sound of a coin on the screen.[/quote]

 

[RingProfessional]

Big crushed pop cans do sound like coins to me also. They imitate coins real well.