Voodoo Main Discussion

[MartyJ1963]

@Qiaozhi and 6666,,Thanks for the info guys, Regards, Marty.

[lamoiz]

my copy arrived this day. I start reading and translating for the correct understanding. I am very happy. now i start work.

[Orbit]

Eclipse I don't think he'll work with coil for SD2200 or any of the gpx series because it is in my estimation in question more vlf detector ,right on I work with pi which uses a coil for VLF and for now it works great I work with OO coil and can work with concentric VLF coil...
And if help is needed Microelectronics I have a couple of good friends who work in Mikroe!

[eclipse]

I'm not sure I couldn't find proper info /Goldbug and F2 coil data, but if any good I can obtain those on the really cheap side/.

But I've just managed to snatch a Fisher F75 SEF (Detech) coil for 1/2 of the price while the coil is brand new.
I also have original Minelab 28cm DD coil for SD2200, co-planar 45cm for SD/GPX (Detech); Vlf coils I have Minelab Musketeer (specs are really close to F75, need to recheck but probably TX inductance would be to high), I have XT17000 and FT16000 minelab VLF coils, DeepTech Vista Gold 28cm and 35cm which can also be measured if any good.
Too bad all my stuff is all scattered in several different locations so it's going to be a journey to put things in some order.

[Polymer]

The Voodoo Project <<- Click to view book on Amazon

A Pulse Induction Metal Detector with Iron Discrimination

Pulse induction metal detectors are very sensitive to ferrous (iron) targets, and one that can ignore iron has been a sort of holy grail for metal detector developers for some time.

The Voodoo Project is a written record of the author's personal mission to design and develop a working pulse induction (PI) metal detector that is capable of good iron rejection.

Voodoo is a hybrid detector with features of both a PI and a VLF. The design goal was to develop a PI that can be used both inland and on the beach. In particular, special attention was devoted to finding non-ferrous targets in areas infested with ferrous trash. Rejection is not based on target conductivity, as Voodoo provides true ferrous/non-ferrous discrimination.

This book is available worldwide exclusively on Amazon.

Thought I would post my "internal" parts list, might help someone, in addition to the BOM in Post 1.

I like having the pitch of capacitors known, as there often is a lot of choice when ordering
and I just hate forcing radial and box capacitors pins if they dont fit exactly.

Open for suggestions and errata of course, cheers, polymer

Voodoo_Pitch_Parts.pdf

[Qiaozhi]

I can obtain a coil for F75 and a coil for both GoldBug and Fisher F2. Is the F2 & GoldBug suitable for this project as i prefer the price on this one a little bit better.

What are the inductance values of the Goldbug and F2 coils?
I measured the F75 loops as TX = 696uH and RX = 6.9mH.

[Qiaozhi]

Red+Black= 14.6 ohms / 2.42mH
White+Green = 26.5 ohms / ?
Can't measure inductance at White+Green.

The inductance of 2.42mH is too high for a PI detector.
From my experiments I would suggest a range from 300uH to 500uH as optimal, although I did have good results from an inductance as high as 1.12mH.

[Qiaozhi]

Thanks Qiaozhi. Can the outer loop be multi-stranded wire (eg:-16 strand PTFE coated 600v 0.5mm wire), or should I use a single core wire with thick insulation? I have 4 types of copper enamelled wire at hand,,0.18mm,,0.25mm,,0.5mm and 0.72mm,,which would be best for the inner coil if I made the 'Large' concentric and the 'Small' concentric? Thanks for the guidance, Regards Marty.

Multi-stranded PTFE wire will be good for the outer loop. For the inner loop you can use 0.18mm or 0.25mm.

[mschmahl]

Even if you order the book directly from amazon.com.au it stills ships from the U.S.A.?
Does Amazon Australia not have the ability to print-on-demand?

It?s the same in Germany. I have ordered on Amazon.de and it is delivered from UK.

[eclipse]

I can obtain a coil for F75 and a coil for both GoldBug and Fisher F2. Is the F2 & GoldBug suitable for this project as i prefer the price on this one a little bit better.

[6666]

Thanks Qiaozhi. I've been searching the internet for a Troy 9" Concentric coil to buy but can't find any at the moment. If I wanted to make a DIY version of the Troy what would be the best wire gauge to use for both TX and RX coils please?,,in case I can't find a commercal one. Also, can the Voodoo pcb be made without the battery charger pcb so I could use an ordinary (Separate) Battery pack? I'd lke to be able to change batteries as they deplete. The main reason I'm wanting to build this project is that I want a detector that I can mainly use inland. I haven't done much beach detecting as I live 2 hours from the closest beach (And I never learnt to drive) and I'm absolutely surrounded for miles with Farmland, fields and tons of Woods/Woodland. For inland use I mainly use my Minipulse Rev-D, my Mirage or my T2,,,actually, I prefer my DIY detectors any day to my T2. It'll be great to finally have a DIY detector with ground balance and be able to explore all my local countryside where I live,,,I'll have no need then to find a beach!!,Lol. Thanks again, Marty.

Have a look at fig 10-9 in ITMD
PCB's have arrived in Melbourne, just got to get DHL to deliver them.

[ivconic]

What is the inductance of the TX and RX loops?

Red+Black= 14.6 ohms / 2.42mH
White+Green = 26.5 ohms / ?
Can't measure inductance at White+Green.

[MartyJ1963]

Thanks Qiaozhi. Can the outer loop be multi-stranded wire (eg:-16 strand PTFE coated 600v 0.5mm wire), or should I use a single core wire with thick insulation? I have 4 types of copper enamelled wire at hand,,0.18mm,,0.25mm,,0.5mm and 0.72mm,,which would be best for the inner coil if I made the 'Large' concentric and the 'Small' concentric? Thanks for the guidance, Regards Marty.

[Qiaozhi]

Q. i have here 26cm coil for newer Bounty Hunter models. Sitting here for long time unused. Brand new, indeed never used.
It probably have capacitor poured in resin inside the coil. Assuming it is 220nF.
Any chance...?

What is the inductance of the TX and RX loops?

[ivconic]

Q. i have here 26cm coil for newer Bounty Hunter models. Sitting here for long time unused. Brand new, indeed never used.
It probably have capacitor poured in resin inside the coil. Assuming it is 220nF.
Any chance...?

BTW book arrived to address in CH.
Now is matter of time when it will be "bus"-ed from there to here.
Hopefully soon.