Another question; Pi's & momentary reverse disc.?

[Anonymous]

Hello again! Seems kinda slow, so I figured that I'd try to get things going by asking about something that's been bothering me for a bit. I think someone asked about this a while ago (who knows, coulda been me) but I forget the answer & specifics. Anyway, as you probably know by now I've purchased an Infinium. Supposedly one can determine, to a degree, if there is iron under the coil by advancing the disc. (delay) to maximum; the so-called iron check setting. Well, this is a bit of a time waster, having to then rotate the pot back to it's original position which might not be zero. So, instead of doing that, I figured that a momentary switch, like the Troy coincheck, could be used. So, is this a practical solution or am I just blowing smoke? ...Willy.

 

[Anonymous]

Willy, while anything maybe possible, I think you have to realize that no one is working on doing Infinium mods. You have a good system with a way to check iron, be satisfied with that and go out and find some gold. HH...Don

 

[Anonymous]

While it's true that I have an Infinium, it's not the only detector on the market that has a delay setting that can be advanced to "disc." out certain things & help ID others. I feel that the momentary switch to a different setting without changing the original setting is still a valid idea regardless of make. Now, my electronic knowledge is severely limited as well as funds, otherwise I'd try it out myself. There are also situations wherein a person is pressed for time & would like to dig the maximum # of "good" targets. Thumbing the dial works, but is still a time waster. Check out the multitude of vlf machines with target ID. A lot of that info can be obtained by thumbing the disc. on non-ID units. One detector that people are waiting for is the "Pulse Devil" PI detector. Supposedly has (or will have) target ID. If no-one wanted ID there wouldn't be such great interest in it. In the meantime, gotta settle for second best. ..Willy.

 

[Anonymous]

You are correct! everybody has been waiting, but developments have been slow coming out. I think the knowledge to do is there, except no one will spemd the money to do it. I think most mfgers regard nugget hunting as a minority of their detector sales. HH...Don

 

[Anonymous]

Willy,
If you had a PI,with a 555 timer to controal uS.
with a 2 way switch,you can increase restance at
pin-?.(555 IC)to increase uS.It will lower dept on
non-ferrous metals,can be used as a DIS.
I have tryed it, it works.will not say what pin or
pins.You might damage your PI.
Some-one else can give you more imput.

 

[Anonymous]

Hi Willy and Don,
Although, TID may be great, it might not be the answer for a serious nugget hunter. Having used a multitude of TID machines, I can say that it is impossible to tell gold from so many of the other non-ferrous objects. In fact, gold objects will span from iron to a half dollar or more on a typical TID meter, depending upon the size of the gold and the purity.
What makes things worse is the fact that iron will fall in the same range at times, depending upon its orientation, shape, etc. So, one could get nice low conductive signal from a piece of old can under the right conditions.
What is really needed for a nugget hunter is a true form of iron ID. The problem lies in the fact that no one circuit will work. Large solid iron objects can be checked using the delay advance method you mentioned, but thin flat metal trash such as tin cans, will give a perfectly good signal only using the delay method. In other words, thin iron, such as cans, will have a decay quite similar to a gold object and will require a different form of detection.
I know, I have been fighting such trash for a long time. It has been one of my pet projects to try to find something that will minimize the digging of the can type trash. I already have a PB I can push to quickly advance the delay to test for heavier iron, but like I said, this will not work on the tin can problem.
I have just built a simple but somewhat effective circuit that I hope will work in the field as well as it does in my testing. Even if it does work as I hope it will, the design is still limited. The trash has to be reasonably close to the coil (within 6 to 8 inches or so, depending upon the size), and real small pieces, smaller than a quarter, will be almost impossible to eliminate. Fortunately, such small pieces are the minority where I hunt.
I am hoping to test the design shortly.
Reg

 

[Anonymous]

Hi Willy,
It is quite possible to have a delay control in the form of a switch, or pushbutton, as well as a knob. This would give instant "reverse discrimination", as it is called. There are two problems, one that has been overcome and one that may not have been, as far as I know. The first is, that suddenly shifting the delay by a few 10's of microseconds, causes the receiver circuit to go out of kilter for a short while. This gives rise to some serious ear bashing, until the SAT has settled things down again. To prevent this, an audio blanking circuit has to be added, to quieten things down in this period. This has been done experimentally, both by Reg and myself, and it works fine.
The second problem is that for nugget hunting a ground balancing circuit is desirable for working in medium to strongly iron mineralised ground. If you shift the delay to do an ID, then the ground balance setting is no longer valid, and you would have to re-balance. I don't know if the Infinium has auto or manual balance, but the auto balance would have to react pretty fast to be effective, otherwise a false reading would result.
Reverse discrimination, although better than nothing, has only limited use in ID'ing iron, as Reg says.
Eric.

 

[Anonymous]

Hi Reg. I generally dig everything when prospecting 'cause that nugget might be under the chunk of trash iron. Of course, this theory breaks down in a trash pile. However, there are situations where any kind of disc. is beneficial. I can't count the number of times that, while nuggethunting, I came across an old camp or foundations. Hunting in all metal then becomes an exercise in frustration. My buddy Jim gave up in disgust when hunting just such a site with his Gold Bug (came upon it while nuggethunting); iron trash everywhere. I then went & hunted it with my garrett Scorpion. The flip reply would be "have 2 machines"; yea right. I'm not carrying 2 detectors all over the mountains, nor am I gonna hike all the way back in later to detect an area that's probably barren of finds anyway. Another area in which disc. is of great benefit is the aforementioned coin/ring hunting. True, vlf units are (for now) superior re. ID/disc., but there are some situations where they fall flat due to mineralization. Not to belabour the point, but such is the case where I live. Below about 4" ID readings on a vlf become extremely unreliable & a vlf won't punch down more than about 6" except on really big targets (often iron) which will read good. This is where the PI potentially shines re. depth & the possibility of ID'ing iron. Regardles of that, it's good to see that someone has actually incorporated a momentary "iron check" feature on a PI. Now, all I have to do is bug Garrett; maybe they'll give me some info (doubtful but worth a shot). ..Willy.

 

[Anonymous]

[No message]

 

[Anonymous]

Hi Eric. In regards to the Infinium, it has 3 settings: fast/slow ground track & lock. A switch could probably be put in that put the tracking into lock while engaging the temp. delay setting, activating the audio blanker at the same time. I also remember a previous thread on this forum wherein the two tone system (Minelab, Garrett) was discussed. The upshot of it was that, when implemented, advancing the delay would also shift the break point where a low conductor is differentiated from a high conductor (audio indication). Experimenting with the Infinium, which has this system, I have found such to be the case. A canadian $1 coin reads as a good conductor. Advancing the delay to about 4 causes an abrupt flip, it would now read as a poor conductor. $2 coins do the same thing, but at 6 on the dial. I also found that at maximum delay a 10 kt mens' ring will still be detected but will read as a low conductor, along with the coins. I'll pull out some silver coins later on to see how they will react. just the fact that current Canadian coins exhibit this behavior is exciting; at least for me.. I'm Canadian. In an area with a multitude of targets, having the pushbutton delay setting would save a lot of time when hunting coins/rings, especially when there's a lot of iron trash. I'm not talking 100% ID by any means, but digging %50 less iron can be a major benefit, especially if it's 2' down in hardpan. ...Willy.

 

[Anonymous]

Hi Willy,
If you want to have some fun with your Canadian coins and have a TID machine, just ID them with the coin flat on the ground and then orient the coin so it is about 45 degrees or so and see if things don't change. What you should see is a sudden shift in ID because of the magnetic properties of the coin. At least, that is what I experienced with a couple of ID machines I own.
I was surprised when I first tried experimenting with Canadian coins at the request of a Canadian. It wasn't until I found out many of them would stick to a magnet that it made sense.
Reg

 

[Anonymous]

Hi Reg. just goes to show to what lengths the government here will go to shaft us <img src="/metal/html/cry.gif" border=0 width=40 height=15 alt=":cry"> . That's one of the things that makes it such an adventure detecting up here. Most TID machines are calibrated for US coins & also don't have the mid-conductivity resolution required for our coins. Also, ID readings on our coins rely on the day of the week as well as planetary alignment, but I don't really care to delve into such esoterica at the moment. I've used many TID units here & have been uniformly disappointed. Gonna get my Cobra II soon & might consider modifying it to be capable of accepting the cointrax (w. the new chip), mayne it will do a bit better. Hopefully it will be able to deal with yhe extreme mineralization here better than the other units I've tried. ..Willy.