coil size

mascard1

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Oct 28, 2008
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In general concept, yes, it would reduce the size of the detection field. However, a lot of variables can come into play and at times you can even hunt deeper with a smaller coil. So things can get a little complicated, but in general principle, a smaller coil will produce a smaller field and thus less depth.
 

From my limited knowledge, if coil size is the only variable, I'm inclined to agree with the OP.

However there's also a separation issue. Lets spoze you've got a silver dime at 8" and some junk at 6"...
The smaller coil may be able to pick out that dime, whereas the junk may mask it from the larger coil. In this case, it could be argued that the smaller coil reaches deeper (but that may be a stretch).

I hope I've explained this correctly.
 

If I put a 5" coil on a machine that came with a 11" coil ...is that going to change depth gauge?
My buddy says no ...I say yes?
I’m talking about the depth gauge on the machine… if a 11” coil shows 4 inches on machine( two bars)…. Would a 5” coil show 2 inches on machine ( one bar)… on same target…do they just the depth gauge to the size coil that comes with machine?
 

I’m talking about the depth gauge on the machine… if a 11” coil shows 4 inches on machine( two bars)…. Would a 5” coil show 2 inches on machine ( one bar)… on same target…do they just the depth gauge to the size coil that comes with machine?
Why is knowing the depth so important?

Just asking because it's something I have never focused on while detecting.
 

Depth, like everything else, is susceptible to error due to the variables of target size, shape, and even it's position in the ground, etc. "Returns" are based on many different factors.

I wish there was an easy answer for you but there isn't. Per example, a larger coil presents a larger search field, so in theory a larger coil will cover more surface area and detect deeper.

However, a larger coil can also allow for more contaminants to enter the search field at any one time which can result in decreased sensitivity settings in order to achieve a stable operation. On the other hand, since a smaller coil allows for less contaminants to enter the search field at any one time it may then become possible to run that smaller search field at increased sensitivity or even full sensitivity which, at times, can even allow the smaller coil to hunt deeper and with far more efficiency than the larger one.
 

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I’m talking about the depth gauge on the machine… if a 11” coil shows 4 inches on machine( two bars)…. Would a 5” coil show 2 inches on machine ( one bar)… on same target…do they just the depth gauge to the size coil that comes with machine?
That would depend on whether the depth gauge(s) is/are absolute or relative. Since they're usually represented in bars instead of numerically, I'd guess relative.

As bigscoop noted, with all the variables, it would be very difficult to get accurate absolutes.

Why is knowing the depth so important?

Just asking because it's something I have never focused on while detecting.
Likewise. As a newb, there's so much to remember about digging a friggin' hole in the ground.

If there's a signal, I'm going to dig a hole. Beyond that, everything is incremental. To paraphrase Shakespeare...
"The [plug's] the thing." Once that plug is out, any further digging is USUALLY minor (though it can be frustrating).
 

I’m talking about the depth gauge on the machine… if a 11” coil shows 4 inches on machine( two bars)…. Would a 5” coil show 2 inches on machine ( one bar)… on same target…do they just the depth gauge to the size coil that comes with machine?
I would say yes, especially if the detector is calibrated to an 11" coil. However, it is quite possible for a detector manufacturer to automatically calibrate the readout to take their size options into account with a coil ID. An example is the XP Deus which pairs with their various coil options using a coil ID. So the answer is "it depends".
 

Why is knowing the depth so important?

Just asking because it's something I have never focused on while detecting.
I have a site that was a gathering place for many from 1840 to 1890's.
I only dig targets targets 6"+ there. That's where the pay layer for old stuff is there (generally speaking).
 

I only dig targets targets 6"+ there. That's where the pay layer for old stuff is there (generally speaking).
Can I follow you around and dig all the stuff you're leaving? 😁
 

I haven't notice any significant depth reading differences when changing from small coils to large coils. Actual detection depth, sure, depth reading on a target, no.
 

I do a lot for old coins around me.
You must just do urban grass hunting only then.
Is that correct?

Though from digging targets for over 5 decades I have found 100 yr large coppers laying under the dry leaf litter-down to 14" in the same park.(off the lawns)
There's no definitive depth for coinage it seems as silvers seem to be at every depth.
I'm sure you must have figured it out though to only dig a certain depth target.
 

You must just do urban grass hunting only then.
Is that correct?

Though from digging targets for over 5 decades I have found 100 yr large coppers laying under the dry leaf litter-down to 14" in the same park.(off the lawns)
There's no definitive depth for coinage it seems as silvers seem to be at every depth.
I'm sure you must have figured it out though to only dig a certain depth target.
Like you, I still find "old" silver and copper coins less than 3-4" deep, others much deeper.
 

There's no definitive depth for coinage it seems as silvers seem to be at every depth.
I'm sure you must have figured it out though to only dig a certain depth target.
I think we get more variation in depth here up north than areas that don't experience regular frost heaves. BICBW.
 

My buddy and I were just talking about this and I thought I would ask…about if the depth gauge changes with coil size… I usually don’t even use it ( The depth gauge)… I like the sounds to be fainter.. the deeper it is…
 

My buddy and I were just talking about this and I thought I would ask…about if the depth gauge changes with coil size… I usually don’t even use it ( The depth gauge)… I like the sounds to be fainter.. the deeper it is…
Everything is based on the strength of the returns. Depth, Target ID, it can all be effected by target size, target density, target shape, target conductivity, and even a target's position in the ground. Even coils of different sizes that have been calibrated for the same machine can often return slightly different target ID, etc.

As good as today's machines are it's the targets and the ground and the manner in which they lay that can still create "a lot" of inconsistencies.
 

Can I follow you around and dig all the stuff you're leaving? 😁
Ha! Be my guest. If you're digging the first 4-5 inches at this site your getting slaw, bottle caps, pull tabs, and clad. Maybe an occasional rosie. There are early 1800's coins and relics there, but they're deeeep.
Some guys love stabbing clad, but I don't find it enjoyable at all. I have loose change in my car and my couch if needed. :D
 

There is "a lot more" to coil size then most realize. Different coil sizes can have significant impacts on everything from depth to even different responses and/or no responses at all to the targets encountered. Even target separation capabilities can be significantly impacted by coil size.

Per example, and detecting the same ground conditions, if I were shooting for quarter sized items even in trashy ground I'd opt for a larger coil, while just the opposite would be true if I were targeting smaller dime sized objects in this same trashy ground.

For those who don't quite understand just much influence coil size can have on the process the above statements might cause them to scratch their heads. But for those who do understand the full impacts that coil size can have on the process the above statements will make sense.
 

Ha! Be my guest. If you're digging the first 4-5 inches at this site your getting slaw, bottle caps, pull tabs, and clad. Maybe an occasional rosie. There are early 1800's coins and relics there, but they're deeeep.
Well, both my coils have proven to reach at least 12" deep. I've picked up bits of rusty brad 1 cm long, and and foil about 1/2 cm sq. at 10" deep.

Which program (or settings) have also made a difference.
 

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