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.