DIY Pulse Induction Detector (Impulse III)

[AlphaAnton]

Hello everyone!

I recently wanted to get into gold prospecting and detecting but due to a tight budget we were not able to invest in anything high quality when it came to detectors. I often become obsessed with an idea and when I figured that I couldnt get a detector for a while I started looking around at experiments and DIY projects. Eventually I came across a video of a guy that tests various DIY electronic projects and had a few metal detectors he had made. The most recent being a Pulse Induction metal detector which I could buy the PCB off ebay so I decided to give it a go and see how much I enjoy using it.

Here is a video of me testing it for the first time in the backyard showing my old man. I will add a picture of it when I get home too.
View attachment 10000000_5762773460499796_7004301521683807276_n.mp4


For this build I have used so far:
PCB off ebay
0.4mm Enamel Coated Copper Wire
Some old speaker cable to connect everything together
3D Printed ABS parts
PVC Pipe
Some M3 nuts and bolts for the housing




It was pretty simple to get going as I just had to solder a battery, speaker and coil. The shaft I used a PVC pipe, the coil housing and unit/battery housing were 3D printed with ABS plastic. The first head I used a curved channel and wrapped the wire. The second head I made I used a flat channel and have made more of an effort to stack the copper wire neatly and I used the amount of coil windings they suggested in the instructions for optimal use (the first head had less copper windings). I am currently looking at optimising the size and sensitivity of the coil to see if I can use it to find some gold nuggets somewhere, maybe out at Warwick or Northern NSW. I am not too knowledgeable with electronics so what I have been able to work out is limited. But recently I came across some videos by DetectorMods on YT and he has a few videos where he has a some coil heads dismantled. The Pulse Induction coil heads all have a conductive shield of sorts, encasing the coil head and a tiny wire connected but I can't seem to work out where this wire goes. Not sure if the PCB needs something on it to attach the wire to ground the shield? Of if it can be grounded in another way. Either way, if you have any knowledge on this, please share!

One thing I had been struggling with is finding a bolt and nut that isnt metallic for the head. I have printed one using ABS but it was difficult to get correct and I have since threaded it so I have gone with just gluing the head together before I make my next iteration.






I have since taken it out a couple times, once to a small beach with my daughter and we pulled up a bit of rubbish of various sizes. Had a blast doing it. Then we went to Gympie on the way up to Bundaberg for a camping trip and picked up an old button. I was amazed that I was able to pick up something so flat and small. It was a good 6 inches deep (wish I measured).



Took it to an old gold mine where there were a heap of other people detecting too, found some 'relics' and a chunk of what seemed to be copper ore. No one else was finding anything so I was alright with that, but I would like to test its sensitivity on some gold nuggets and jewellery (surprisingly havent yet).
I am currently re-designing the housing and adding a handle, I want to bring the screen, buttons and speaker up onto the handle for ease of use (especially after designing it upside down to start with...) but I am also looking to add a headphone jack so I don't annoy others too much when needed.



Thank you for reading, I will keep this updated with future updates, and once I am happy with the design ill share the 3d Print files incase anyone else wants to take on the same project.

 

[Jaros]

Great going on the PI.

 

[XLOOX]

I think you have done very well - PI coils do not need as precise setup as VLF ones as in mainly the one coil for TX & RX but you have made a working detector and that is huge.

In VLF & IB coils a seperate wire is sometimes used to help balance but the details are beyond me.

Best resource online is www.geotech1.com
and best book is "Ïnside The Metal Detector" by Overton & Moreland which balances practical building tips with electronics has 8 DIY detector designs & some coil building.

 

[AlphaAnton]

I think you have done very well - PI coils do not need as precise setup as VLF ones as in mainly the one coil for TX & RX but you have made a working detector and that is huge.

In VLF & IB coils a seperate wire is sometimes used to help balance but the details are beyond me.

Best resource online is www.geotech1.com
and best book is "Ïnside The Metal Detector" by Overton & Moreland which balances practical building tips with electronics has 8 DIY detector designs & some coil building.

Thank you! Pretty stoked with the result so far. I have a goal of finding a gold nugget with it one day so I shall keep learning and tinkering. Thank you for the info I will definitely check it out!

 

[bicter]

Thank you! Pretty stoked with the result so far. I have a goal of finding a gold nugget with it one day so I shall keep learning and tinkering. Thank you for the info I will definitely check it out!

Well done getting it up and running. For nylon bolts have a look at toilet seat bolts.
The shield in the coil is only connected at one point and usually wires back to 0v on the pcb.

 

[user 4485]

I've got some nylon bolts here somewhere for coils. If I can dig them up I'll let you know - you can have them.

 

[AlphaAnton]

I've got some nylon bolts here somewhere for coils. If I can dig them up I'll let you know - you can have them.

Appreciate it, Bicter suggested toilet seat bolts, I was going to check those out so please dont go to any trouble!

 

[Rockwall]

Appreciate it, Bicter suggested toilet seat bolts, I was going to check those out so please dont go to any trouble!

Minelab shop or ebay.

 

[user 4485]

Appreciate it, Bicter suggested toilet seat bolts, I was going to check those out so please dont go to any trouble!

I don't have any of the actual Minelab nylon bolts left but do have some I'd used on other detectors &/or as spares. They are 1/4" x 2". Unfortunately I don't have any wing nuts left that fit them but do have plenty of normal nylon nuts to suit.
Let me know how you go but they are there if suited. I won't use them all.

 

[1955lennie]

Hi,most DIY pulse induction Coils only run 2 wires- input from machine to coil- output back to the machine a continuous loop and shielding doesn't need to be grounded . This is how l build my own pi coils,also you can use a metal bolt on your coil if it's attached permanently.l often sticky tape a gold nugget to mine to prove that it doesn't make a difference you can also use toilet seat plastic bolts of your that concerned. When making pi coils be aware of how many revolutions of wire you use,there are actual diameter coil winding charts on the internet.

 

[Bush]

Interesting Post Lennie, quote : a continuous loop and shielding doesn't need to be grounded.
i think you are saying the faraday shields do not need Electrostatic SS drain wires and that basically just non magnetic conductive cups are needed covering the coil workings...

 

[bicter]

Hi,most DIY pulse induction Coils only run 2 wires- input from machine to coil- output back to the machine a continuous loop and shielding doesn't need to be grounded . This is how l build my own pi coils,also you can use a metal bolt on your coil if it's attached permanently.l often sticky tape a gold nugget to mine to prove that it doesn't make a difference you can also use toilet seat plastic bolts of your that concerned. When making pi coils be aware of how many revolutions of wire you use,there are actual diameter coil winding charts on the internet.

Using metal on the coil is a nono. While it mightnt be detected by the coil, it will affect the sensitivity of the coil.
The shielding of the coil cable needs to be terminated at the detector end to provide effective shielding.

 

[Bush]

I found this site PI coil building by Mr Rodowaski.
It is very in depth and a little out side my parameters to fully understand.

https://www.geotech1.com/pages/metdet/projects/fastcoils/FastCoil.pdf

What i`m seeking is views and opinions of the drain wires formulas , cals and restraints ie shapes , length proportional to coil size ratio ect.
Having now stripped down a few coils there seems tobe various designs ie ; straight upper and lower, curved and even twound rim.
The angles also vary right angle and adjacent or vertical to horizontal pending which way you hold the coil.
From what i can gather is the length of the non magnetic drain wire is half the length of the coil width.
Would it be functionally possible in this case basically spoke coil to place the wires in curve upper / lower on the opposing curve.
If anyone herewith has any further experienced and knowledge about this your views would be most helpful and appreciative.
regards Bush.

 

[1955lennie]

I found this site PI coil building by Mr Rodowaski.
It is very in depth and a little out side my parameters to fully understand.

https://www.geotech1.com/pages/metdet/projects/fastcoils/FastCoil.pdf

What i`m seeking is views and opinions of the drain wires formulas , cals and restraints ie shapes , length proportional to coil size ratio ect.
Having now stripped down a few coils there seems tobe various designs ie ; straight upper and lower, curved and even twound rim.
The angles also vary right angle and

adjacent or vertical to horizontal pending which way you hold the coil.
From what i can gather is the length of the non magnetic drain wire is half the length of the coil width.
Would it be functionally possible in this case basically spoke coil to place the wires in curve upper / lower on the opposing curve.
If anyone herewith has any further experienced and knowledge about this your views would be most helpful and appreciative.
regards Bush.

Basically configuring DD coil.
When l build my coils their mono coils power in power return,your. main concerns are coil circumference X wire loops and uhms resistance in that field winding ,for EMI l shield wrap the winding and run clip on EMI resistors on my cables,l have found this to be an effective system and l have been building coils this way for the past 10 yrs. Whilst experimenting l found if l put a smaller wound coil winding not attached to the outer field winding inside the casing l get a 20% deeper detecting rate and where l detect around the Bendigo area which is known for its hot ground my mono coils do well.

 

[Bush]

Thanks Lennie,
The Dark Trade Secrets of Coil Building that cannot be taken with us when we depart.
Why not put it out there with a little Fame in history to assist the small fella.
cheers.

 

[lazypat]

Hello everyone!

I recently wanted to get into gold prospecting and detecting but due to a tight budget we were not able to invest in anything high quality when it came to detectors. I often become obsessed with an idea and when I figured that I couldnt get a detector for a while I started looking around at experiments and DIY projects. Eventually I came across a video of a guy that tests various DIY electronic projects and had a few metal detectors he had made. The most recent being a Pulse Induction metal detector which I could buy the PCB off ebay so I decided to give it a go and see how much I enjoy using it.

Here is a video of me testing it for the first time in the backyard showing my old man. I will add a picture of it when I get home too.
View attachment 9705


For this build I have used so far:
PCB off ebay
0.4mm Enamel Coated Copper Wire
Some old speaker cable to connect everything together
3D Printed ABS parts
PVC Pipe
Some M3 nuts and bolts for the housing

View attachment 9703


It was pretty simple to get going as I just had to solder a battery, speaker and coil. The shaft I used a PVC pipe, the coil housing and unit/battery housing were 3D printed with ABS plastic. The first head I used a curved channel and wrapped the wire. The second head I made I used a flat channel and have made more of an effort to stack the copper wire neatly and I used the amount of coil windings they suggested in the instructions for optimal use (the first head had less copper windings). I am currently looking at optimising the size and sensitivity of the coil to see if I can use it to find some gold nuggets somewhere, maybe out at Warwick or Northern NSW. I am not too knowledgeable with electronics so what I have been able to work out is limited. But recently I came across some videos by DetectorMods on YT and he has a few videos where he has a some coil heads dismantled. The Pulse Induction coil heads all have a conductive shield of sorts, encasing the coil head and a tiny wire connected but I can't seem to work out where this wire goes. Not sure if the PCB needs something on it to attach the wire to ground the shield? Of if it can be grounded in another way. Either way, if you have any knowledge on this, please share!

One thing I had been struggling with is finding a bolt and nut that isnt metallic for the head. I have printed one using ABS but it was difficult to get correct and I have since threaded it so I have gone with just gluing the head together before I make my next iteration.

View attachment 9704View attachment 9710View attachment 9711




I have since taken it out a couple times, once to a small beach with my daughter and we pulled up a bit of rubbish of various sizes. Had a blast doing it. Then we went to Gympie on the way up to Bundaberg for a camping trip and picked up an old button. I was amazed that I was able to pick up something so flat and small. It was a good 6 inches deep (wish I measured).

View attachment 9706View attachment 9707View attachment 9712

Took it to an old gold mine where there were a heap of other people detecting too, found some 'relics' and a chunk of what seemed to be copper ore. No one else was finding anything so I was alright with that, but I would like to test its sensitivity on some gold nuggets and jewellery (surprisingly havent yet).
I am currently re-designing the housing and adding a handle, I want to bring the screen, buttons and speaker up onto the handle for ease of use (especially after designing it upside down to start with...) but I am also looking to add a headphone jack so I don't annoy others too much when needed.

View attachment 9708

Thank you for reading, I will keep this updated with future updates, and once I am happy with the design ill share the 3d Print files incase anyone else wants to take on the same project.

Coʻiltek at maryborough and minersden usually sell coil bolts n nuts and there should be some engineering places that would also sell them

 

[Bush]

Coʻiltek at maryborough and minersden usually sell coil bolts n nuts and there should be some engineering places that would also sell them

Another alternative is Trade Fasteners Suppliers.
i think though most Au supply is metric fine thread personally i like imperial course in nylon.

 

[Bush]

Another alternative is Trade Fasteners Suppliers.
i think though most Au supply is metric fine thread personally i like imperial course in nylon.

Black is imperial 1/4
White is metric M6
Black bolt in nylon is less susceptible to cross threading with the deeper grooves.
White is a stronger compound but tends to strip and cross thread.
Super glue white wing nut to nut helps to minimize cross threading.
Go black if you can get it.

 

[Bush]

Does anyone really know about the electromagnetic fields in relation to detector coils and if there is any verification on the photon patterns.
There seems tobe many different examples of diagrams and drawn pictures but are they just modelling assumptions or are they correct.

You Tube ; Visualizing Invisible Energy Fields.

 

[Bush]

GPZ 7000 coil opened up.
A variety of adhesive glues , various gauge wires & componants.
Good luck trying to replicate this one.
It really is a Dark Art as old mate called it..
but it` great to see thinking out side of the box otherwise The Song Remains The Same.