Whites SPP information and questions

[PhaseTech]

I beg to differ. Gold is one of the best conductors running 3rd to Copper and Silver.

Maybe pure gold once it is refined, but natural gold is a whole different ball game. Lots of impurities and unusual shape/structure can make gold a really poor conductor. This is why VLF's can hit hard on certain gold that is invisible to most PI's.

 

[Jaros]

Pinched from Google.

Different metal detectors work in various different ways, but here's the science behind one of the simpler kinds. A metal detector contains a coil of wire (wrapped around the circular head at the end of the handle) known as the transmitter coil. When electricity flows through the coil, a magnetic field is created all around it. As you sweep the detector over the ground, you make the magnetic field move around too. If you move the detector over a metal object, the moving magnetic field affects the atoms inside the metal. In fact, it changes the way the electrons (tiny particles "orbiting" around those atoms) move. Now if we have a changing magnetic field in the metal, the ghost of James Clerk Maxwell tells us we must also have an electric current moving in there too. In other words, the metal detector creates (or "induces") some electrical activity in the metal. But then Maxwell tells us something else interesting too: if we have electricity moving in a piece of metal, it must create some magnetism as well. So, when you move a metal detector over a piece of metal, the magnetic field coming from the detector causes another magnetic field to appear around the metal.

It's this second magnetic field, around the metal, that the detector picks up. The metal detector has a second coil of wire in its head (known as the receiver coil) that's connected to a circuit containing a loudspeaker. As you move the detector about over the piece of metal, the magnetic field produced by the metal cuts through the coil. Now if you move a piece of metal through a magnetic field, you make electricity flow through it (remember, that's how a generator works). So, as you move the detector over the metal, electricity flows through the receiver coil, making the loudspeaker click or beep. Hey presto, the metal detector is triggered and you've found something! The closer you move the transmitter coil to the piece of metal, the stronger the magnetic field the transmitter coil creates in it, the stronger the magnetic field the metal creates in the receiver coil, the more current that flows in the loudspeaker, and the louder the noise.

 

[Ded Driver]

I beg to differ. Gold is one of the best conductors running 3rd to Copper and Silver.

Jaros I may be corrected, but I think the terminology has been muddied by various data over time.
As I understand it in relation to gold, the term 'Not a good conductor' (in respect of metal detectors) actually refers to the low inductance field it generates . I think most people know it is a very good conductor of current, but doesn't respond the EM fields the way iron & other metals do.
Maybe someone here with some solid Electrical/Electronic knowledge can shed some light on this? And maybe this is also a bit off topic & could be moved to another thread?!

 

[Jaros]

It's a very relevant topic.

 

[Moatazfaize]

Example if I move the solder (electronic relatio for solder) straight near spp not detect
And if I make it round it'd detect ,

 

[Ward69]

I had the same problem , when I first bought a sdc. Thinking it was the sdc. But it was me. I bought a couple of test nuggets ranging from 0.19 to 1.08 Place on top of ground. Played with settings. Place a few inches down played with settings. Found out it was my ears. The sound is Little different to lead or iron. Personally I need to run on 5 and around 3 freshhold Then slow down your walking , lower the better coil to ground. Good luck. Mark

 

[Ridge Runner]

Example if I move the solder (electronic relatio for solder) straight near spp not detect
And if I make it round it'd detect ,

This is what Phase Tech was saying, There are many types and reasons a PI machine won't see Gold, ranging from shape or structure or porosity just to name a few, this is where VLF's have the edge because they can see Micro metals of all shapes and sizes where the ground conditions become a VLF's enemy where some models can't see the gold because of the minerals, Where as a PI can be made to ignore the minerals but also are blind/ignore certain types Gold,

All PI's have a blind spot where certain target types fall through a Hole and that is where the GB point meets the frequency, This becomes more noticeable On a Whites because everything is Manual as with the QED so getting the settings right is very important more so than with an ML machine because ML Machines are set up to do the task at hand, Where a Good VLF will see 99.9% of Gold Targets if it is within range and it has a good tracking system.

 

[steelPHASE]

I beg to differ. Gold is one of the best conductors running 3rd to Copper and Silver.

Jaros I may be corrected, but I think the terminology has been muddied by various data over time.
As I understand it in relation to gold, the term 'Not a good conductor' (in respect of metal detectors) actually refers to the low inductance field it generates . I think most people know it is a very good conductor of current, but doesn't respond the EM fields the way iron & other metals do.
Maybe someone here with some solid Electrical/Electronic knowledge can shed some light on this? And maybe this is also a bit off topic & could be moved to another thread?!

You guys are all sort of correct.

PI detectors are basically looking the signal induced in the target (which decays over time) by the TX pulse . Although it is a very good electrical conductor, gold can have a very short decay time (although depending on the sizer and shape this can vary). We are talking micro seconds. Sampling very close to the end of the TX pulse to see this decaying signal is very difficult (mainly due to high back emf voltages generated by coil etc).

If ground balance is not set up correctly, noise canceling hasn't been done, Threshold to high (or too low), swing speed to fast, target too deep for the machine - all these can contribute to missing targets.

The other thing to mention is that doing tests in air, in a suburban environment, will never be a good indication of the machines capability. There is so much EMI and interference that if you get the machine to behave, it will not be running at its optimum.

(note: I did edit this several times as I tend to type as my brain thinks - very scattered and only understandable only to myself lol)

 

[Jaros]

Keep it going - what an interseting little subject.

 

[Ridge Runner]

I beg to differ. Gold is one of the best conductors running 3rd to Copper and Silver.

Jaros I may be corrected, but I think the terminology has been muddied by various data over time.
As I understand it in relation to gold, the term 'Not a good conductor' (in respect of metal detectors) actually refers to the low inductance field it generates . I think most people know it is a very good conductor of current, but doesn't respond the EM fields the way iron & other metals do.
Maybe someone here with some solid Electrical/Electronic knowledge can shed some light on this? And maybe this is also a bit off topic & could be moved to another thread?!

You guys are all sort of correct.

PI detectors are basically looking the signal induced in the target (which decays over time) by the TX pulse . Although it is a very good electrical conductor, gold can have a very short decay time (although depending on the sizer and shape this can vary). We are talking micro seconds. Sampling very close to the end of the TX pulse to see this decaying signal is very difficult (mainly due to high back emf voltages generated by coil etc).

If ground balance is not set up correctly, noise canceling hasn't been done, Threshold to high (or too low), swing speed to fast, target too deep for the machine - all these can contribute to missing targets.

The other thing to mention is that doing tests in air, in a suburban environment, will never be a good indication of the machines capability. There is so much EMI and interference that if you get the machine to behave, it will not be running at its optimum.

(note: I did edit this several times as I tend to type as my brain thinks - very scattered and only understandable only to myself lol)

That's the trouble with the TDI's the frequency does not go down low enough, being 10 on the Delay dial, 8 would be good 7 would be better, another issue with the TDI's is depending where you set the GB you can make some targets vanish and others jump out loud.

The TDI SL is all but immune to EMI and lightening near by and domestic EMI has little or no effect and I have used mine in the city with thunder storms going over head.

A lot of the trouble with the TDI's is their Coils, they are just not hot enough and the DF ( Duel Field ) is even worse than the Oz version where the 7.5" shows very little change between it and the 12" coil, The sensitivity is about the same with both coils and the only benefit of the 7.5 is it fits in tighter spaces. I was so unimpressed with the 7.5 that I gave it away to a mate after 15 minutes of testing,

To get a TDI to seen smaller bits the only way is by getting Luke's tune up done, or if you can't catch up with him just fit Minor John Coils etc.

 

[Moatazfaize]

dear :-

i think if we can add the width key to spp or we can adjust the frequency for the spp in tx and rx Capacitors pcb board as i haired one year back some eletronic engineer did this in other type .

because i get the beep sound waw waw for Small iron nail 0.4 but i cant get other type like Tin or foil .

i think if there any electronic idea it will be help full .

rgds

 

[Moatazfaize]

See dear this son a one here call Karl's

#10
User is Offline KarlS

Member
From: Blacktown, NSW
Joined: 14 February 2014
Posts: 678
06 August 2014 05:29 am
I just finished bit of testing of new 11" DD coil. The targets were 0.6 and 6,5 grams pieces of lead, buried in 8 cm and 12 cm in the ground. The SPP ground balanced on default setting. The White's 7.5" mono coil picked 6,5 grams but failed to sound on 0.6 grams.
The Minelab Commander DD picked up both targets with clear signal.
Karl

White's SPP, XTERRA 705, old Tandy detector
.prospectingaustralia.com/forum/viewtopic.php?id=7630

 

[Ridge Runner]

See dear this son a one here call Karl's

#10
User is Offline KarlS

Member
From: Blacktown, NSW
Joined: 14 February 2014
Posts: 678
06 August 2014 05:29 am
I just finished bit of testing of new 11" DD coil. The targets were 0.6 and 6,5 grams pieces of lead, buried in 8 cm and 12 cm in the ground. The SPP ground balanced on default setting. The White's 7.5" mono coil picked 6,5 grams but failed to sound on 0.6 grams.
The Minelab Commander DD picked up both targets with clear signal.
Karl

White's SPP, XTERRA 705, old Tandy detector
.prospectingaustralia.com/forum/viewtopic.php?id=7630

The Factory coils have trouble seeing bit below 0.17gms, But they will see the bits you have except not as deep as other branded coils, that why I said you need minor john's coils.

 

[Moatazfaize]

I will try to build search coil for this .. as the factory coils it has only one coil tx and rx in same time

 

[Moatazfaize]

And they make short in tx rx point in board so the search coil 2 ohm working mono one time tx and other time rx ,,

So I am going to make super d coil tx and rx so to Increse the detect .

Also I found there is jumper in down of board which relation between tx and rx and the arc

Plz if any idea it will help

Rgds

 

[Ship of fools]

And they make short in tx rx point in board so the search coil 2 ohm working mono one time tx and other time rx ,,

So I am going to make super d coil tx and rx so to Increse the detect .

Also I found there is jumper in down of board which relation between tx and rx and the arc

Plz if any idea it will help

Rgds

By super D coil do you mean Flat wound DD or DOD like the GPZ 7000?
Also what size coil would you look at making?
Certainly be interesting to see your results.
Matt T

 

[Moatazfaize]

I mean DoD like gpz7000

But I miss some information hop I will find it

Because here I have one coil in spp working in two ohm tx and rx , they make short cable between
Tx and rx main cable ,

Now i want to make separate cable one for tx and other for rx ,, I want know if the machine accept to work like this , then what information about tx file micro frad and ohm etc, ,

Also we need replacement jumber poison which its under board

Rgds

 

[Ridge Runner]

It's not worth the messing around, before you waste time and money on trying to build a coil for it you would be better off borrowing or trying a small minelab or coiltek coil on it first just to see if it will see the small gold because if it won't using those coils then you are wasting your time.

 

[steelPHASE]

Its extremely unlikely you will be able to get it to run with a Double D coil as per the 7000. Besides trying to get all the coil specs to match the whites, the timings will need to be altered. It wont be just as simple as changing a link on the board.

Also to get the coil specs you need to measure the capacitance and inductance of the coil. DC resistance is only a small part of the equation. In a mono coil, its a combination of these factors that determines overall coil speed and its ability to see small gold.

Too be honest you are better off trying a small commercial coil first before you start playing with your machine. If you make a coil and its not close to spec, you run the risk of blowing up the fets in the TX stage of the detector.

 

[user 4485]

Simple thing to try first would be (as already suggested) try a small coil like a Nugget Finder Sadie 8"6" mono, Coiltek 6" coil etc. Here's a thread on several small coils being tested on the Whites TDI Oz Pro : https://www.prospectingaustralia.com/forum/viewtopic.php?id=21209
The Nugget Finder Sadie is a standout IMO.
There are a few mods around for the SPP including turning it back into a TDI SL - same board just has been "dumbed" down for the SPP model. I believe there is also a mod to reduce the pulse delay down to 8us (from 10us) which will make it more sensitive to small gold as well as noise reduction mods etc. If the noise reduction mod is done then you may also need to consider an increase to the voltage but not over 18 volts. Making a pack up with 4 x li-ion batteries will give you a max. of around ~16.8v or nominally 14.8v.
Do some research & look up an American by the name of Reg Sniff who has a huge knowledge of what can be done with the TDI platform. He no longer performs the mods but has written a lot about them on US forums - the guy that was doing the mods with Reg's input was Paul Montgomery ([email protected]) but not sure if he still does.
Luke Lindsay was doing SPP/TDI mods here in Australia but doesn't seem to be on forums anymore. Last I heard he was using an Australian made QED detector.