Voodoo Main Discussion

[lamoiz]

Hi all,,,Has anyone started to build the Voodoo yet? Thanks, Marty.

I'm just starting ... especially the coil. but I have not had the answers to my questions. I'm also waiting for some components. I programmed the microcontroller

[lamoiz]

I don't know if I'm making a concentric, or an omega or a super D (mini) ... voila .. the concentrics are not easy to humbucking coil.

[6666]

Hi all,,,Has anyone started to build the Voodoo yet? Thanks, Marty.

Still waiting for book ordered Oct 14

[MartyJ1963]

I'm just having a bit of trouble reading the schematics in the book with them being so small but I'm also a little confused as to which terminals are '+' or '-' on some of the 'PL' (2-Pin) connectors and the speaker connector. Really don't want to start building till I know what's what. @Qiaozhi,,Could you look at the pic I posted and tell me which is which please as I'm a littl confused? Both diagrams say 'Rear view'. Regards, Marty.

[MartyJ1963]

@6666,,Hope it arrives for you soon. Did Trev contact you about obtaining a board from you? Can't wait tll the thread starts getting 'Busy' with building this project! Regards, Marty

[MartyJ1963]

@Lamoiz,,,I don't think the Voodoo coil has a ' Bucking' coil. I believe it just consists of an outer loop, the TX, and the inner loop, which is just the RX. The TX Coil has a parallel Damping resistor and the RX Coil has a parallel Capacitor. Someone can correct me if I'm wrong or mistaken,,,Regards, Marty.

[Qiaozhi]

I'm just having a bit of trouble reading the schematics in the book with them being so small but I'm also a little confused as to which terminals are '+' or '-' on some of the 'PL' (2-Pin) connectors and the speaker connector. Really don't want to start building till I know what's what. @Qiaozhi,,Could you look at the pic I posted and tell me which is which please as I'm a littl confused? Both diagrams say 'Rear view'. Regards, Marty.

Both diagrams are the "rear view". The top one is for the socket, and the bottom one is for the plug.

[Qiaozhi]

I don't know if I'm making a concentric, or an omega or a super D (mini) ... voila .. the concentrics are not easy to humbucking coil.

As you see from Chapter 6, all the coils were of the concentric type except one. The exception was the Fisher F75 DD coil, which had a slight disadvantage when the detector was switched into PI mode.

[6666]

@6666,,Hope it arrives for you soon. Did Trev contact you about obtaining a board from you? Can't wait tll the thread starts getting 'Busy' with building this project! Regards, Marty

Hi Marty, yes Trev has his pcb and book

[MartyJ1963]

Thanks Qiaozhi for those answers. So these concentrics then have no bucking coil, is that right? @6666,,Glad you sorted him out, he's a good frend of mine and great bloke,,,I know his good wife Bridgitte bought him the book for a Xmas pressy and he's worried now that when she wraps it up in Xmas paper he won't be allowed to read it until Xmas day!,,LOL.. I sent him a Felezjoo pcb to have a play with,,,he's going to let me know how it handles with our highly mineralized 'Aussie' soil,,,It'll be great to see what yours and Trev's results are using the Voodoo on Aussie soil too,,,Hope your book comes soon, Regards, Marty.

[Qiaozhi]

Thanks Qiaozhi for those answers. So these concentrics then have no bucking coil, is that right?

Wrong.
The concentric coil type requires a nulling (bucking) loop to cancel the TX signal in the RX loop.

[MartyJ1963]

Thanks Qiaozhi. Regarding the 'Small' coil in your book I.E:- Outer loop= 7"@306uh and Inner loop=3"@467uh,,,How would I calculate the amount of turns for the Bucking coil please? This is the first coil I'd like to attempt to make for my Voodoo build. Regards, Marty.

[6666]

Thanks Qiaozhi. Regarding the 'Small' coil in your book I.E:- Outer loop= 7"@306uh and Inner loop=3"@467uh,,,How would I calculate the amount of turns for the Bucking coil please? This is the first coil I'd like to attempt to make for my Voodoo build. Regards, Marty.

hi Marty check out this doco, has some good info and may help https://www.geotech1.com/cgi-bin/pag...anar/index.dat

[eclipse]

The book is very good read. I have ordered a set of 5 boards for try out.

[Qiaozhi]

Thanks Qiaozhi. Regarding the 'Small' coil in your book I.E:- Outer loop= 7"@306uh and Inner loop=3"@467uh,,,How would I calculate the amount of turns for the Bucking coil please? This is the first coil I'd like to attempt to make for my Voodoo build. Regards, Marty.

The document linked to by 6666 describes the process of building a concentric coil very well.