Menu
What's new
Find's Treasure Forums

Welcome to Find's Treasure Forums, Guests!

You are viewing this forums as a guest which limits you to read only status.

Only registered members may post stories, questions, classifieds, reply to other posts, contact other members using built in messaging and use many other features found on these forums.

Why not register and join us today? It's free! (We don't share your email addresses with anyone.) We keep email addresses of our users to protect them and others from bad people posting things they shouldn't.

Click here to register!

Need Support Help?

Cannot log in?, click here to have new password emailed to you

P.I. Discrimination

A

Anonymous

Guest
Given that ferrous/non-ferrous targets decay at different rates, why wouldn't it be possible to have two receiver channels tuned for example to 15 microseconds and 50 microseconds. The difference in response could be used to generate a ferrous/non-ferrous tone?
 
The problem is that medium and high-conductivity nonferrous targets have decay times comparable to that of iron targets in various orientations.
It is possible to discriminate between low-conductivity nonferrous, and iron, using the approach you suggest. Many years ago I built a PI which discriminated high-conductivity nonferrous from iron and other nonferrous.
In principle, it is possible to do both in the same machine, and for all I know Minelab may already be doing it. It does get somewhat complicated, and the resulting signal-to-noise ratios are not as good as you'd get from reactive discrimination of the type you find in VLF induction balance metal detectors.
--Dave Johnson.
 
I have learned to love water/underwater hunting in the ocean and freshwater. I do the most hunting in Florida although I am now living my my motorhome and travel most all over the US. I have read many times that saltwater has a method of taking care of iron targets. As a underwater hunter I can assure you this is not correct, there are thousands of bottlecaps, co2 cartridges, nails, screws and dock material of iron all in the waters of Florida, GA, SC and NC, TX and so on. From my conversations with many of the daily hunters of Florida they all know the PI is far better at depth and sens. to gold in the water, underwater. However in a days time of digging iron parts with the other trash is a true negative and most give in to using a VLF water machine because they deal with the iron better and eliminate most all of the iron digging. When underwater with 35 pounds on your back and shoulders and using a mask and snorkle eliminating the un-needed digging of iron is a blessing and one can only say with it so many hours without totally getting pooped. I personally am extremelly interested in the PI units from a users point of view and own one. But I would own two or three if there was a method of eliminating or "bonging", some kind of audio or lighting a light to let you know the iron targets. I have 9 detectors now and would buy more and get rid of my others if I had a PI that would "warn" of iron targets. Is there anyone who is really seriously nearing that mark in the growing of the new generations of PI detectors? I can assure the market buyers are ready for that product. I have been reading this forum for over a year and almost daily. I know in the last couple of month some of the most intelligent individuals have joined in and are sharing information. I am so delighted to see this and know that in the future the future is PI detectors. I can truthfully say I understand only about 10 to 15% of what I read but am thrilled to attempt to understand and more excited when I actually do, but I know this type of educated individuals getting together can only mean good things in the future.
I can only be a cheerleader and a buyer and I will be that for you....Frank Hamill
Sorry this took so long to express my thoughts.
 
A P.I. machine that could tell the difference between low conductivity items (smaller gold rings, etc.) and ferrous would be better than what we have now. At least SOME of the time you would know whether it was ferrous. I'll take one!
 
Porter,
Check Eric foster's detectors. Mr Bill will attest to the fact that The Deepstar and other detectors already do what you are looking for.
Click on the Surfscanner link at the top of the page and e-mail Mr Bill. It is my opion that you will be hard pressed to beat one of Eric Fosters detectors. All the best, Dave. * * *
 
From what I've read, the HH PI has a type of discrimination that works 70% of the time. While not true discrimination, it's better than nothing. Maybe Mr. Bill can elaborate.
 
A couple of years ago I inadvertantly discovered a way of getting a PI to discriminate, AND IT WORKED!!!
If you look VERY closely at the dv/dt of the LOWER portion of the decay from the coil, then you'll see that it changes, one way for ferrous materials, and the other for NON ferrous.
Sampling this decay using a Digital scope, with a delay on the trigger, made the near vertical edge of the initial pulse, move one way or the other, depending on the nature of the target, i.e. iron or gold. this movement is VERY pronounced.
A nifty bit of circuitry to emulate this, would entail a delay in the signal path, but the trigger would be immediate.
Sample using a 14 bit A to D, store the results in RAM, then finally analyse using a micro.
You'll find that the depth this system will pick up a
 
You must log in or register to reply here.
Top