Making the CZ less sensitive to iron...

Tom,

...is there a way to lower the CZ's sensitivity to iron so that it would not falsely read it as a high tone as much? Not discriminating it out exactly, just making adjustments so that it has to really work at it to give a piece of iron an iron grunt, so to say. I thought of changing out the resistor on the "disc 1" notch on my CZ3D so that it would still detect iron, but not so readily. I didn't look close enough to see what was on the "disc 0" notch. It's at work so I'll take a closer look tomorrow.

I can see that this could loose some really deep coins that the CZ has problems accuratly IDing, and so will many times give a low iron tone.

Maybe there's a way to move really "weak" "deep" signals up to a different tone, so at least it would get our attention. If a detector can see and know something is really deep, and the signals weak, I would rather it give me a "dig" signal instead of an "ignore" signal!

Is any of this possible?

That is one thing about the cz that bugs me also. The coil reads out the sides and has me sweeping unecessarily....Little one inch nails 8+ inches down I get high tones 90% around the target. After I get my 75 serviced, I'll send the cz to Tom, it may need a little tweaking.

I just bumped up a old thread on Finds CZ Forum.
Title CZ - 70 is a relic hunter. Im not a electronics guy but
it did catch my eye some time ago HH Mike.

Nature of the beast ought to cover it but their are ways to tell and wanted to wrap my original CZ6 around a tree after digging 8 deep rusty nails but rarely dig one now but after an iffie get fooled now and then.

If it don't repeat from at least two directions leave it lie, a coin is a short sound while iron covers a lot more area,if it sounds like a foot deep and meter is registering 5-6 inches probably iron, once you make a plug the pinpoint seems to move to the side of the hole is another tell tale sign, finally deep silver coins just sound more mellow and iron is sort of screechy(hard to explain) and takes time in the field.

As far as the technical question your up Tom...

gman: I had come across that post several times in my searches. The OP's english was a little tricky to understand at times, but it sounds like he was a relic hunter that wanted larger pieces of iron to ID as a high tone... opposite of what I had in mind. I'm not 100% sure of this, as he also said that the modification would cause deep coins to ID as a high tone on the CZ instead of sometimes giving a low tone.

I'm hopeing to find a way that will make the CZ a bit "less" sensitive to iron in hopes that doing so will help prevent it from giving the low to high tone bounce. That, and change the detectors IDing of a target that is deep and weak to a high tone instead of low. This might be possible only if the CZ is directed to give a low tone on anything it cannot readily identify.

Clear as mud, huh?

Pinpoint and make sure the signal you heard is centered with the pinpoint. You will get false signals to the side on iron.

Rick, N. MI

Connor.......... you are asking one question..... but needing the answer to another (unasked) question. I happen to like both questions.
First......... I'll answer the question that you probably meant to ask. You are wanting the iron to 'false' a LOT less...... and want to know how to do this. Yes.......... you can. It is incongruent to what you would expect (a paradox).... and what many people feel uncomfortable doing. When iron falses (to a high-tone) too much........... rotate your Grnd Balance clockwise (lower numbers) until you reach a minimum amount of iron falsing. Your specific TYPE of iron..... and your specific decomposition status.... dictates 'where' that Grnd Bal set-point will be. ((( Forget about your Grnd Bal being used to compensate 'dirt' balance; rather..... it'll be used to mitigate iron falsing ))). You may not get rid of all falsing....... but will be able to correct a certain amount of it.......... and........... what DOES remain as 'falsing'...... will now be a bit more intelligible. Remember........... different sites will have different Grnd Bal set-points. No two sites will be alike. Iron rust flecks/flakes are the worst offenders. The tips (and heels) of nails are the next worst offender. . . . along with 90-Deg bent nails.

Next question. "Can you lower the Sensitivity on the CZ to iron". Can you 'detune' Sensitivity to iron........ and simply make the CZ less-sensitive to iron.. . . . more difficult to detect. This is in the engineering design architect. A coil will radiate/emanate electromagnetic energy...... that is dicatated by the frequency of the detector. It is specifically in the frequency of the detector that dictates how 'resonant' the unit will be to iron. Then....... along with (what ever) frequency of the detector....... "HOW" sensitive the detector is configured (Sens/gain)...... as to how small and/or deep it'll detect/report a target. This is something that you do not have control over; .............. short of buying/using a different detector with a different operating frequency.

I don't want to forget to mention: GROUND MOISTURE also plays a role in 'iron falsing'. In my low-mineral soil....... wet ground 'activates' the iron to a greater degree...... and more falsing ensues.......(along with easier/deeper detection). Some areas of the United States...... higher mineralization and extremely dry conditions....and the iron will false to a greater extent. This is something that you will (more probably) intuitively learn.... as you accrue more experience.

Making very deep/weak signals a different tone. This would be fairly easy to do (from a factory/engineering stand-point); yet, the operator would lose the entire amount of "detector attempt" to ID the target. Deep targets have their own language..........and..........after some time.......... the operator can begin to understand that language. . . . along with 'how' the detector responds characteristically. (Modulated audio already performs your requested intent). Some of the older units had surface-blanking........ and could perform this function....... to a certain extent (but not necessarily a different tone for deep targets). I believe modulated audio still performs your intent...the best.

..."Forget about your Grnd Bal being used to compensate 'dirt' balance; rather..... it'll be used to mitigate iron falsing."

I would never had thought of using the GB to detune some of the iron out! It really makes sense when you think about it.

If you had sterile soil, with no minerals or salts in it, we would not 'need' to ground balance a detector. But if you took different metals and ground them up into small particles of dust, then mix that dust (along with some salt) into the sterile soil, ...then you need to somehow cancel out all that 'mineral dust' and salt before the detector can see what else might be in the mix. Ground balancing is nulling out the effects of the unwanted minerals already in the soil. Your area may have more or less minerals in the soil than mine, thus our ground balancing settings would be different.

Once we have accurately nulled out the effects the minerals and salts in the soil are having on our particular detector, THEN we can, as you described, use it (the ground balancing control) to help null out other iron and minerals that we might come upon.

How ingenious!

If we do this, what negative effects might we see by going too far with it? ...and if we "go too far"... can we compensate somewhat by increasing the sensitivity, or would that just put us back where we started from?

This is great stuff ...at least for me. May be old hat to you though :-)

Your answer to the second question is also very enlightening. If you want a detector that does not have a love affair with iron to begin with, you need to find a frequency that it will operate on that does not resonate well with iron. That is why some detectors have less trouble with iron than others. The ideal detector would operate at a frequency that does not resonate well with iron, but 'does' resonate well and be sensitive to silver and gold. ...piece of cake! Anything close to this?

As to the last question... a modulated tone being one that changes in volumn? ...or pitch? ...or both? I can see that a modulation in volumn will tell me it's deep (or very small), and that is what I use at present. If I were to add a patch somewhere on the circuit that would give me a high tone on any target that the CZ3D could not identify, then you're saying I would lose the ability for the detector to give me any 'hints', so to speak, of what it might be? If this is correct, I think I would sacrafice the CZ3D's 'hint' ability just to know that the target is too deep for the detector to accurately identify to begin with. This would save me time playing around with a weak sound, pinpointing to guess it depth, (8+ inches?) listening to see if I can get the detector to give me some kind of tone other than "low", and still most likely not know if I should dig or not. If I 'knew' a target was over 8 inches and could not be identified, I would dig it anyway. I would probably have whatever it is out of the ground and in my hand before I had even decided to "dig or not" the other way.

I am so glad (and I know other posters here are also) that we have somewhere to go and someone that can give us knowledgable answers about these things! Thank you so much!

Connor



Edited 1 time(s). Last edit at 09/04/2011 08:15PM by connortn.

Because there are so many variances in dirt....... using the Grnd Bal control to mitigate iron 'falsing'..... must be experimented with. If you find a Grnd Bal position that minimizes iron falsing.......... you (then) need to verify that deep (good) targets will still "ID" correctly .... (this could be the side-effect).

The lower the operating freq of the detector..... the more resonant the unit is to silver (and less resonant to iron and gold).

The CZ3D, being a dual frequency detector, ...does it use one freq. for "enhance" and the other in "salt", or are both freq. running simultaniously?




Man... we need a spell check on this forum :-) My spelling must be about 3rd grade!

The CZ continuously transmits/receives 2 frequencies (and harmonics). This is what allows CZ's to function well on the wet salt beaches. Same with the upper-end Minelabs. Multiple freq's (run through a comparator) is a requirement (technologically......thus far) , , , , in order for a unit to function 'well' (and perform 'well') in a wet salt environment. There are plenty of units on the market today that can transmit/receive many frequencies ....... but not at the same time. You might even be able to 'select' the frequency of your choice ... with these detectors; yet...... once again..... many of these units only give you the option of selecting ONE frequency at a time. Some of these units might even claim "wet salt function". I have yet to witness a single freq unit that would function 'well' in a wet salt environment.

For the past 20 years...... I have been utilizing a 'standardized' test to see if a unit will function 'well' in a wet salt environ. I have never openly-admitted/shared/divulged this information before. I utilize a U.S. 3-Cent nickel ONLY (because it's a low conductor). I will bury the 3-Cent nickel to a depth that matches the diameter of the coil to be tested. For example; if the Whites MXT comes with a Blue Max 950 coil......... this coil is 9.5" in diameter............. I will bury the 3-Cent nickel at 9.5" in the wet salt...to test the detector....... and seek a 'pass/fail' scenario.
There is a 'catch' to this testing. If the coil is smaller than 6.5"..... or larger than 12"....... the test is invalid. In general... small coils will ascertain depths greater than their diameter. Large coils (in general) will lose sensitivity to coin/ring sized targets.

((( Pulse Induction (PI) is a completely different platform......... usually single frequency operation. )))

Thanks for the info Tom. Reading on the three cent coin , thy were 75/ 25 % silver / copper from 1851 - 53
and changed to 90/10 % mix from 1854 - 73

NO, NO, NO!!!!!!!!!! NOT the 3-Cent silver coin. Use the 3-Cent NICKEL. It is exactly the same composition as a nickel. 75% copper and 25% nickel. There is a HUGE difference between a 3-Cent silver......and...... a 3-Cent nickel!!!! The 3-Cent nickel was first produced in 1865.

That makes more sence.