DIY Pulse Induction Detector (Impulse III)

[Bush]

Coil Works in Progress.
1. 12`` coil foam insert.
2. New coil top & base. Armstrong bucket base & 20 liter oil tub.
3. Base & coil workings
4. Conductive painted shields.
5. 13`` Shield plate Ohms resistance test.
6. 13`` Shield 1.5 AAA battery DC volt test.
7. 8`` shield Ohms test.
8. 1940`s 8`` shield Ohms test.

 

[Bush]

NF 12`` Coil Modified re-build for SDC2300.
Air tested maximum faint signal depth results in mm.
Lead shot fishing sinkers.
0.46 g ... 30 mm
0.9 ... 45
1.5 ... 135
5g ... 190
10 ... 210
46 ... 240
104 ... 270

Results disappointing as no significant depth advantages over the standard OEM 8`` coil.
Conclusion ; Faraday shielding coatings are excessively conductive as predicted ref post Modified SDC2300.
Coil weight 860 grams.
Re-Hash on the cards.

 

[IBGold]

NF 12`` Coil Modified re-build for SDC2300.
Air tested maximum faint signal depth results in mm.
Lead shot fishing sinkers.
0.46 g ... 30 mm
0.9 ... 45
1.5 ... 135
5g ... 190
10 ... 210
46 ... 240
104 ... 270

Results disappointing as no significant depth advantages over the standard OEM 8`` coil.
Conclusion ; Faraday shielding coatings are excessively conductive as predicted ref post Modified SDC2300.
Coil weight 860 grams.
Re-Hash on the cards.

Hi Bush,

What shielding are you using if Graphite based should be 65 to85 ohms per inch resistance.

If using Nickle , Copper or silver based conductive spray that will be your problem.

Regards, Ian.

 

[Bush]

Hi Bush,

What shielding are you using if Graphite based should be 65 to85 ohms per inch resistance.

If using Nickle , Copper or silver based conductive spray that will be your problem.

Regards, Ian.

Hi mate,
The F1A4 coil shield is 0.086 ohms / 1`` that is with the meter set on 2K.
My shields are not a consistent coating from a spay gun applied mixture of carbon / graphite & activated carbon & water base paint but a reading of 0.55 is average of which i think is too conductive but in saying that i have not been able to register a detected target signal of the shields using another 8`` coil testing them with the sdc so unless the new shields are being detected and are not audible and the sdc is identifying a target signal of the shields and reducing this NF 12`` coil sensitivity but maybe not ?
Other factors maybe coming into play like Litz wire coil winding resistance and winding counts ect.
It would take me years to understand the mathematics in these calculations so i just have to best heed to whatever some of the Pros have to offer that may help us all out.
regards.

 

[trav34]

yeah , i found the same thing PI detectors are expensive and i think they make it that way due to the greed of people wanting to find gold

 

[Bush]

yeah , i found the same thing PI detectors are expensive and i think they make it that way due to the greed of people wanting to find gold

Trav34.
You have been found guilty of presenting a post in the wrong Topic ...
Don`t feel bad as we all have done similar acts of the same.
Fact is i don`t know how this Coil Topic got misplace on what was originally a DIY Pulse Induction Project Topic.
PA Rules are written there as a guideline for a purpose ...
In General Chat i think anything goes so next time a comment like above maybe better placed.
Moderators at times will re-direct a Topic to the right category with or without warning.
Nice to met you & welcome to this Forum.
Now i have to dig out my credit card & scrap up funds tobe a supporting member.
What a Great Day.
Cheers.

 

[IBGold]

Hi mate,
The F1A4 coil shield is 0.086 ohms / 1`` that is with the meter set on 2K.
My shields are not a consistent coating from a spay gun applied mixture of carbon / graphite & activated carbon & water base paint but a reading of 0.55 is average of which i think is too conductive but in saying that i have not been able to register a detected target signal of the shields using another 8`` coil testing them with the sdc so unless the new shields are being detected and are not audible and the sdc is identifying a target signal of the shields and reducing this NF 12`` coil sensitivity but maybe not ?
Other factors maybe coming into play like Litz wire coil winding resistance and winding counts ect.
It would take me years to understand the mathematics in these calculations so i just have to best heed to whatever some of the Pros have to offer that may help us all out.
regards.

Hi Bush,

With meter set to the K range 0.086 is 86 ohms so in the ball park with the shield have you got a 3mm break so the detector is not seeing the shield as a shorted turn if it is that will kill the sensitivity keep at it I have been playing building coils for since 1976 and still learning.

Regards, Ian.

 

[IBGold]

Hi Bush,

With meter set to the K range 0.086 is 86 ohms so in the ball park with the shield have you got a 3mm break so the detector is not seeing the shield as a shorted turn if it is that will kill the sensitivity keep at it I have been playing building coils for since 1976 and still learning.

Regards, Ian.

Hi Bush,

This is what I mean.

Regards, Ian.

 

[Bush]

Hi Bush,

With meter set to the K range 0.086 is 86 ohms so in the ball park with the shield have you got a 3mm break so the detector is not seeing the shield as a shorted turn if it is that will kill the sensitivity keep at it I have been playing building coils for since 1976 and still learning.

Regards, Ian.

Thanks for the heads up IB Gold i really appreciate it.
I`m reasonably clued up on the basics on Coil re-builds and Faraday Shields now but by no means spectacular on the subject.
I`ve refined my solder weld joins down to a small tee for litz wire connections and trying to avoid excess solder as small targets.
I came up with a small sandblaster idea to knock the enamel coatings off the multi strand fibers and square cut the ends & minimal lead wipe / dip / primed all the tips prior any final fixing. Old mate @ Detectronics was saying it is near impossible to match the strands so this solution was the best i could come up with.
What i really would like to know is how the parastatic drain wire actually works and if the RX signal returns through that line.
There is not any information online that i can find about this.
TX / the inner cable wires / RX out the mesh shielding wires inclussive drain wire.
`i` find it difficult to understand but i think relative to the coil windings is the outter is trasmitting & the drain wire is receiving but i don`t really know.
The other old fella is saying that the sdc should be Earthed at the detector end which is from memory how Minelab joined the OEM 8`` coil.
I`m not shore if this other old fella is meaning that the Earth should be connected onto the detector plastic body or just connected to the joining plugs.
On the other hand the F1A4 coil and a few others the drain wire is connected in the base of the coil and it actually seems to work fine.
A strange thought i do have is in this scinario of it is what if the drain wire was connected at the base of the i think RX shielding and again connected Earthed at the top end.
Really interesting stuff all this if only i could see Air bourne Eddys.
The Dark Arts i love it.

 

[Bush]

Hi Bush,

This is what I mean.

Regards, Ian.

Are Wow Ian,
Did you do the coatings ?
It looks perfect.

 

[Bush]

Ok . Question Simplified.
With a Concentric coil the outer coil windings are the TX / transmitting wires.
The separate inner coil windings are the RX / receiving wires.

With the Mono coils there is only outer coil bunched windings.
So i`m in the assumption that the Faraday Shielding is being used as the RX for the receiving channel and also to minimize unwanted eddy currents.
As previously stated i have not found any information about Parastatic Drain wiring relative to detector coils.
Any information relative to the above would be helpful.
Regards.

 

[IBGold]

Ok . Question Simplified.
With a Concentric coil the outer coil windings are the TX / transmitting wires.
The separate inner coil windings are the RX / receiving wires.

With the Mono coils there is only outer coil bunched windings.
So i`m in the assumption that the Faraday Shielding is being used as the RX for the receiving channel and also to minimize unwanted eddy currents.
As previously stated i have not found any information about Parastatic Drain wiring relative to detector coils.
Any information relative to the above would be helpful.
Regards.

Hi Bush,

Yes it is confusing and in some cases a matter of what is easiest and cheapest for the commercial manufacturers I have only built PI coils for SD2000 up to the GPX5000 and including the F1A4 and other brands and in all of these the the coil shielding was connected to the coil ground wire at the coax connection but I am led to believe that the later coils the shield wire is connected at the coil plug whether it be a separate pin or the body of the plug I do not know but their could be sound reasons for doing it that way I have done something similar years ago but cannot remember it making any noticeable difference but will revisit it with a coil I am finishing off.

The coil above is one of mine that I shielded using some commercial shield paint that I was given years ago just mask up first and paint on with a fine haired brush you just have to get the conductive paint to the correct consistency so you can get your required conductivity in one even coat that particular product you could thin down with Methylated spirits was a dream to use.

In a Mono coil in simplified form the coil windings form the TX and the RX Antenna for want of a better explanation and the shielding is connected to the ground side of said antenna.

Regards, Ian.

 

[Bush]

Hi Bush,

Yes it is confusing and in some cases a matter of what is easiest and cheapest for the commercial manufacturers I have only built PI coils for SD2000 up to the GPX5000 and including the F1A4 and other brands and in all of these the the coil shielding was connected to the coil ground wire at the coax connection but I am led to believe that the later coils the shield wire is connected at the coil plug whether it be a separate pin or the body of the plug I do not know but their could be sound reasons for doing it that way I have done something similar years ago but cannot remember it making any noticeable difference but will revisit it with a coil I am finishing off.

The coil above is one of mine that I shielded using some commercial shield paint that I was given years ago just mask up first and paint on with a fine haired brush you just have to get the conductive paint to the correct consistency so you can get your required conductivity in one even coat that particular product you could thin down with Methylated spirits was a dream to use.

In a Mono coil in simplified form the coil windings form the TX and the RX Antenna for want of a better explanation and the shielding is connected to the ground side of said antenna.

Regards, Ian.

Thank you for the summary and explanation in layman terms IBGold.
It sort of clears up for me how mono coils work.
The topic is really high tech stuff especially when trying to adapt a coil that unlikely will be an advancement over the standard sdc 8``coil.
I doubt very much my efforts on a modded coil will ever be a sensitive as the sdc OEM coil.
However if at all i can present a modded coil that possibly could prob a little deeper then potentially in the field it would have some advantages.
I guess if Minelab are not extending their range on the sdc coil subject then the finer specs of the sdc cannot be compromised.
End of the day however i`ve learned how to rebuild mono coils & that for me is invaluable.
Excluding the excess weight of the coil i presented the air test were actually not that bad.
It works but i have not extended the field test yet to see how long the period is prior the sdc finding it non-exceptable.
Another thought i`m having is if the Faraday Shielding is of a higher conductivity & the detector is not registering as a false target.
Could it be possible that the coil may be even better in highly hot ground.
Any thoughts or comments welcome ... whoops The manufacturers are onto it... Lol.
Feel free to PM me.
regards.
What a Great Day.

 

[Bush]

PS : On the above ;
With the air testing i`m using a long metric scale rule with the detector shaft vertical up and coil facing horizontal.
Ball sinkers are attached to fishing line and i just swinging them back & forth until the signal fades out for those depth readings.
The hand & target waving thing i feel is less accurate and prone to errors.
I have some other wack`O ideas on the table but their only wack`O until i can prove any confirmation.
The whole concept of detectors & coils is really amazing considering they have been around since prior pre century.
The question for me arises did they derive from a practical construction approach or from a mathematical calculation.
My guess is the maths came after and was expanded based upon basic working modelling.
Probably the 1st being the Dousing Divining Stick.
Strange to there would be more than a few coil builders on PA but for some reason rarely ever engage in Coil Building Topic Conversations.
At another guess it`s probably their only best kept secret in their arsenal of detecting gear they have over Professional Coil Builders & Retailer
Products.
Nothing ventured nothing gained and it`s way to early in the morning to say cheers.

 

[IBGold]

PS : On the above ;
With the air testing i`m using a long metric scale rule with the detector shaft vertical up and coil facing horizontal.
Ball sinkers are attached to fishing line and i just swinging them back & forth until the signal fades out for those depth readings.
The hand & target waving thing i feel is less accurate and prone to errors.
I have some other wack`O ideas on the table but their only wack`O until i can prove any confirmation.
The whole concept of detectors & coils is really amazing considering they have been around since prior pre century.
The question for me arises did they derive from a practical construction approach or from a mathematical calculation.
My guess is the maths came after and was expanded based upon basic working modelling.
Probably the 1st being the Dousing Divining Stick.
Strange to there would be more than a few coil builders on PA but for some reason rarely ever engage in Coil Building Topic Conversations.
At another guess it`s probably their only best kept secret in their arsenal of detecting gear they have over Professional Coil Builders & Retailer
Products.
Nothing ventured nothing gained and it`s way to early in the morning to say cheers.

Hi Bush,

It is all a matter of compromises and choosing what best works in you situation what you are trying to do is build a coil that has less inter coil capacitance allowing it to be faster and have a higher self resonance than the Manufacturers coil remember they have to supply something that is cost effective not necessarily the absolute best possible, there are many different ways of winding coils and materials that can be used to achieve similar and even better results.

I have a platform for air testing coils but in mine the coil is held upside down and the target is like wise swung over the top on a Kevlar thread with hight adjustment at 78 I am at the end of my building days just finishing off some half built ones but I warn you it gets worse than gold fever.

Regards, Ian.

 

[Bush]

The Bug Yes i know that one hunting Sapphires at Sapphire.QLD. wow now a decade ago.
It grabs all your thoughts of any sanity and projects them onto the one thing.
Like a Hungry Tiger that has not eaten food for weeks seeking it`s prey.
It`s all about The Hunt ....
but in my case still it`s about the best weaponry i can find to do the job without falling in to a hole buying the most expensive and effective gear.
The basics come 1st in priority as best we can.
Nice one IB Gold on the positive note of potentially achieving a DIY coil construction of what i`m seeking.
Hopefully i do not fall down a endless delusional trap and actually get out into the fields before the colour is all gobbled up.
I would not want to be labelled a Lab Rat.. Lol.

 

[Bush]

Found this Link very interesting.
https://en.wikipedia.org/wiki/Bifilar_coil
It helps searching for things when you know a little of the terminology.
It would seem some of my fantasy ideas have already been discovered & i`m not surprised.
I recently briefly experimented with 2 x F1A4 coils mount on top of each other wired in parallel.
The sdc just went beep beep beep so unless my connections were a little dodgy that theory went out the door.
The thought of a twisted pair entered my mind but unless i read it wrong that actually neutralizes of halves the magnetic field.
Correct me if i got that wrong.
I`m thinking now of windings in double wrap but would i need to halve the length of cable to get my unknown correct millihertz if that is correct.
If it was possible tobe able to successfully join the windings litz wire cable i know tobe true i could increase the winding count for a larger coil with the same AWG rating.
As previously said i know not how to use the mathematical formulae for an estimate so a practical approach & some referencing is all i have.

 

[IBGold]

Found this Link very interesting.
https://en.wikipedia.org/wiki/Bifilar_coil
It helps searching for things when you know a little of the terminology.
It would seem some of my fantasy ideas have already been discovered & i`m not surprised.
I recently briefly experimented with 2 x F1A4 coils mount on top of each other wired in parallel.
The sdc just went beep beep beep so unless my connections were a little dodgy that theory went out the door.
The thought of a twisted pair entered my mind but unless i read it wrong that actually neutralizes of halves the magnetic field.
Correct me if i got that wrong.
I`m thinking now of windings in double wrap but would i need to halve the length of cable to get my unknown correct millihertz if that is correct.
If it was possible tobe able to successfully join the windings litz wire cable i know tobe true i could increase the winding count for a larger coil with the same AWG rating.
As previously said i know not how to use the mathematical formulae for an estimate so a practical approach & some referencing is all i have.

Hi Bush,

Not much is new there days I have tried dozen's of different designs some work some do not you just have to try to use the best possible materials for what you want to achieve.

Regards, Ian.

 

[Bush]

IBGold,
Without being pesty.
I`m curious on your Spider Coil.
With such an outstanding design and finish coating and i guess the performance is of the same.
If i may what Detector is it designed and suited for and is it a prototype that you are going to patent and forward onto a manufacture.
I recently have been exploring options on farady shielding coatings as you know i`m wondering if a low dielectric mix of something and teflon has been explored.
We entering into a new phase of technology and development in this Century it is going to be very interesting where it takes us.
It is a shame that the supply of many compounds and materials are being restricted to purchase by the general public.
Some of the Big Guns i think are scared that the back yard bloke might come up with a design that out weighs their over priced some times inferior products.
Jaycar is now not retailing stainless steel drain wire and that is not going to assist the young hobbyist that likes to tinker into electronics.
I`m having trouble accessing good coax signal cable to finish off my coils so i`m being forced to look into purchasing from mainland China.
I have not yet approached all the coil manufactures in this country as yet but have been rejected by one company whom previously did supply me with cable.
One would think an Australian Company would assist Australians in their adventures.
Not very Australian are they as we are being forced to buy from OS.
Once was said that any sale is a good sale you would think that Coiltek & alike could strum up some off cuts off there massive cable rolls to help out.
Maybe now their coils are being built in China which may explain some of the issues they have been having.
Shorely in their stock of return faulty products that have been recalled there would be even second hand cable available for purchase they would get a better return selling that than discarding into the recycle bin.
I guess they just fail to think out side of The Box.
They also fail to realize that some of the better ideas and prototypes are being composed by the Aussie DIY bloke in the back yard garage.
I also state to why PC Lap Tops now do not have an external battery and are now in-built as a company was highly Litigated from refusing to supply parts outside of the product warren-tee.
Some where in the legislation of retail products a Manufacture is obliged to supply parts for the expected life span of goods.
In other words if your coil cable is deteriorating or faulty within standard use regardless it is out of warren-tee but within the predicted life span you should be legally right to request a replacement.
As the user in most cases is not capable of replacing the cable you might be justifiably able to request the manufacture to replace it.
Get a new Coil .. Unlikely.
If the manufacture/s had put in some extra effort they could utilize a type of SPDIF plug to connect detector to coil but they prefer to have us by the balls for our money.
It is fact that errors do occur in the field and leads and cables do get broken and the supplier or manufacturer will reply that negligent of the user is the cause regardless it is still under warren-tee.
So what option do we have Buy new one.
If an item like a detector coil coax shielded signal cable that cannot be repaired or replaced with ease by the average detector then the coil in my mind comes under the category of cheap and disposable.
What a marketing ploy this is and for the price they are expecting us to pay for a new coil.
That`s my rant for the day. PS `` the above may be subject to dyslexia & dialectics don`t shoot the messenger.
Back on subject.
Hey IBGold anymore more pics or results on your coil ?
I`m guessing it`s not yet CIA approved.

 

[Bush]

Re above.
Potential Positive feed back from Coiltek their management team are currenty reviewing their Coax Signal Cable Sale to Public Policy.
Hopefully this is a step in the right direction for DIY enthusiasts & good products will be readily available for Au customers.
Understanding the cable is specifically designed by coiltek we would more than greatful to them if if they come to the party.
The last thing i would not be happy about is sending samples off to China to acquire it from being manufactured OS.