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Thread: Size discrimination with Pulse Induction machines?

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  1. #1
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    Jun 2017
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    All Types Of Treasure Hunting

    Size discrimination with Pulse Induction machines?

    Hey guys, I've been cache hunting for some time now, I had bought a Bulgarian PI that I have since gotten rid of, it would sound off loud on every nail and small piece, no good for my purpose. My question is, will a Pulse Induction machine discriminate out the small trash if you put a bigger coil on it? Say a 40x40" square? Am I better off getting a 2 box Whites or Discovery? Target would be gallon paint can size likely, between 1-3 feet deep (I seriously doubt any deeper than 3). Any input is appreciated, though it would be excellent if someone with a PI and large coil could weigh in or perhaps test their unit with a large coil, so see if it overlooks small trash

  2. #2
    Charter Member
    us
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    Why not use a good VLF / Multi-freq? Paint can size targets show up with a 15" coil at 20"-27" and you can discriminate out a lot of the garbage.
    Phishfarmer likes this.

  3. #3

    Mar 2007
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    Motherlode77, your post/question brings up a good object lesson. One that I have been drum-beating on forum posts for cache-hunters (large objects) for a long time , whenever the subject comes up.

    And that is : Exactly as you have come to find out: That even though it's true that various standard machines (coin/relic and various nugget machines) can get caches JUST AS DEEP (or deeper, in the case of pulse and nugget machines) as 2-box units, yet: The devil is in the details: You ALSO hear all the small stuff too. Thus perpetually digging holes for stuff you're not after. And even when the user tries to tell himself that he "will pass up all the small stuff by only digging the bigger beeps", yet he perpetually having to make judgment calls that drive him nutty.

    Yes it's true that by using super giant coils (I'm talking the size of hoola-hoops) that.... yes .... they loose sensitivity to small stuff (coin sized) and still get big stuff. Thus mimicking a 2-box unit . I can not speak direct your exact question of various PI's when paired with super large coils. I'll let someone else tackle that. But I will say: Why not just use a 2-box unit, if they ultimate goal is that it's going to accomplish the same thing as using a hoola-hoop ?

    And I would politely disagree with Terry's answer: A 15" coil is still capable of finding coin-sized objects. And, while yes, such-a-setup would do as he says on paint sized cans (and mimic depth of 2-box for large objects), yet, as said: The devil is in the details when you also can hear all the small stuff you are NOT after.

  4. #4
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    Quote Originally Posted by Terry Soloman View Post
    Why not use a good VLF / Multi-freq? Paint can size targets show up with a 15" coil at 20"-27" and you can discriminate out a lot of the garbage.
    I actually had a CTX 3030 recommended to me, which I purchased. After field tests on test targets, I realized the thing could easily skip over my possible targets buried 16" or deeper, (I was using the 17" coil) also discriminating out iron would likely skip my target completely as its allegedly buried in a steel pot. I sold the CTX after it completely failed testing parameters. CTX is considered to be the best VLF. PI are much better at seeing deep targets in all soil conditions, the problem like I said is it picks up every nail or tack. So I'm thinking Whites TM 808 or a Discovery 900. But if anyone knows if a PI will discriminates out small trash with a large large coil, I would appreciate the input

  5. #5

    Mar 2007
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    Quote Originally Posted by motherlode77 View Post
    I actually had a CTX 3030 recommended to me, which I purchased. After field tests on test targets, I realized the thing could easily skip over my possible targets buried 16" or deeper, (I was using the 17" coil) also discriminating out iron would likely skip my target completely as its allegedly buried in a steel pot....
    Yes. People will often point to standard machines. And they'll say it's "the best of both worlds" because you can go back and forth between purposes (individual coins AND caches) . And they'll point out that some standard machines, when used with large coils, and set up certain ways, can get the depth of a 2-box unit.

    But as said in post #3 : The devil is in the details. However, I would disagree that the CTX can't be made to mimic a 2-box machine, if done correctly. For example, you could run it in all metal so you don't risk missing a large iron object at depth. But again: You'd be forever bedeviled by hearing all the small stuff.

  6. #6
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    Quote Originally Posted by Tom_in_CA View Post
    Yes it's true that by using super giant coils (I'm talking the size of hoola-hoops) that.... yes .... they loose sensitivity to small stuff (coin sized) and still get big stuff. Thus mimicking a 2-box unit . I can not speak direct your exact question of various PI's when paired with super large coils. I'll let someone else tackle that. But I will say: Why not just use a 2-box unit, if they ultimate goal is that it's going to accomplish the same thing as using a hoola-hoop ?.
    Tom, that's what I think I'll do, get a good 2 box, due to the junk in the areas I'm searching, size discrimination is the best bet I have.

  7. #7
    us
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    Don't buy that "won't hit small stuff" until you try it yourself.

    The people who say they won't hit big stuff may be more accurate. LOL
    Last edited by signal_line; Mar 25, 2018 at 09:51 AM.
    Ouija Board and map dowsing , one and the same. Just tape a map onto the Ouija Board and you have map dowsing.
    Works great if you like wild goose chases and snipe hunts!

    My new motto: L-rods are obsolete.

    Like Cappy sings with his harmonica, "We're all gonna die, but not tonight."

    May you never take one single breath for granted.

  8. #8

    Mar 2007
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    Quote Originally Posted by signal_line View Post
    Don't buy that "won't it small stuff" until you try it yourself.
    ...
    As you see, the OP and myself did "try it ourselves". And, even when thinking "I can just ignore small stuff and over dig the bigger signals" ......... it just never works out in actual application. Also: If you're talking places with carpets of nails and small stuff near the surface, you will never have an accurate mental gauge of big vs small at deeper objects.

    And don't forget: big objects at depth can be a "whisper" and small object near the surface might be a "whisper". Thus better to have the machine that simply doesn't see the small objects FROM THE GIT GO .
    motherlode77 likes this.

  9. #9
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    So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, and if so does it discriminate out small junk?

  10. #10

    Mar 2007
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    Quote Originally Posted by motherlode77 View Post
    So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, ...
    Is such a thing even made ?? That's like hoola-hoop sized (for those of you that remember this kids play-toy from the 1960s and 1970s). Why oh why would someone use a loop that big for md'ing ? To go deeper, while ignoring small stuff ? Then again: Why not just get a 2-box machine ?

  11. #11
    us
    Mar 2003
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    Quote Originally Posted by motherlode77 View Post
    So does anyone have a deep seeker PI machine with a large coil 36x36" or larger, and if so does it discriminate out small junk?
    I have a Detech SSP 2100, I used to have an Analog Systems 104B but it was stolen. They do not pick up small stuff.

    I also have a TF900, TM808, and Gemini 3. Whether I would use a hoola-hoop PI or a 2-box would probably depend on what I'm hunting for and the terrain. The PI will generally go deeper and do better at ignoring small stuff but is awkward to use and not suitable in heavy brush etc.
    Tom_in_CA likes this.

  12. #12

    Mar 2007
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    Quote Originally Posted by Carl-NC View Post
    .... and do better at ignoring small stuff ....
    Hmm, ok. I did find it a bit annoying when ... with the TM 808 .... when I was trying to get the most sensitivity (ie.: super tuned, holding close-as-can to ground, etc...), that I did begin to pick up stuff as small as domino sized objects.

    My objective, in that particular hunt, had been cookie-jar sized objects we'd been commissioned to find. So I eventually found myself holding the unit a tad higher off the ground, JUST to avoid smaller objects, which were ALL OVER in this super junky farm-ranch yard.

  13. #13
    Charter Member

    Jun 2017
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    Carl, what do you mean by "small stuff"? What size range about does it discriminate out?

  14. #14
    us
    Mar 2003
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    Been a while, but I think it basically won't pick up coins and smaller. That's a 1m coil. The larger the coil, the larger the target has to be.

    When at White's, I had designed a TDI-based cache locator, mostly for myself as the company wasn't very interested in it. I had intended to team up with the guy in Idaho who makes the polyurethane blanket coils you can drag behind an ATV. Things didn't work out that way. Most PI's can be run with a large (1m) coil but you run into motion issues if they have an overly fast SAT. The SAT is usually easy to slow down. I think First Texas would like such a product, so maybe I should dive back in. I have way better ideas now than I had at White's.

  15. #15
    Charter Member

    Jun 2017
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    Quote Originally Posted by Carl-NC View Post
    Been a while, but I think it basically won't pick up coins and smaller. That's a 1m coil. The larger the coil, the larger the target has to be.
    This would be either a paint can sized steel, or a glass jug of precious metal coins, it sounds to me like I need a 1m or larger coil. Would you recommend an even larger one? 48" or even 60"?

    Quote Originally Posted by Carl-NC View Post
    When at White's, I had designed a TDI-based cache locator, mostly for myself as the company wasn't very interested in it. I had intended to team up with the guy in Idaho who makes the polyurethane blanket coils you can drag behind an ATV. Things didn't work out that way. Most PI's can be run with a large (1m) coil but you run into motion issues if they have an overly fast SAT. The SAT is usually easy to slow down. I think First Texas would like such a product, so maybe I should dive back in. I have way better ideas now than I had at White's.
    Wow, I am impressed and honored to be talking to a White's engineer. What kinds of motion problems do you run into with SAT speeds? Just out testing the TM 800 the other day, on buried copper to simulate something close to gold or silver, Fast SAT speed it barely picks it up at 3.5 feet, but it sings pretty loud and clear when I switch it to the Slow SAT. Why is this?

    Also, in the TM 800 manual, it states that the machine will indicate over gold and silver while in Cave Mode. Is that true? Sadly the Cave Mode function doesn't work on my machine, I'll have to send it in, if White's still services that machine.

 

 
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