Voodoo Main Discussion

[SilverSurfer17]

Well that sucks book was suppose to be delivered by usps but it didn't come today like it was suppose to im so mixed up on what type of cable is best ive read like 5 different things from rg58a/u cable to mogami dual rca to ubs cable to microphone cable and also to make it as short as possible for a faster coil

[dfbowers]

Thanks Don, but having trouble seeing the meter movement, bit too far away, is that your home-made coil ?

Sorry, Video is so crappy. 480P.. I can see it on my mobile device but the resolution is not that good on my laptop. Yes, home made coil.

[6666]

Since I got the modified Surf PI boxed up. Here is how it works. It’s not a depth monster.. maybe 8” on coins but that’s just the circuit that I picked for the experiment. The disc add on is actually more sensitive than the PI itself.. not sure what the results will be at depth yet. Anyway, if anyone has a video of their VooDoo working I would love to see it for reference.
Don..
https://youtu.be/L613UOxhBdw

Thanks Don, but having trouble seeing the meter movement, bit too far away, is that your home-made coil ?

[dfbowers]

Since I got the modified Surf PI boxed up. Here is how it works. It’s not a depth monster.. maybe 8” on coins but that’s just the circuit that I picked for the experiment. The disc add on is actually more sensitive than the PI itself.. not sure what the results will be at depth yet. Anyway, if anyone has a video of their VooDoo working I would love to see it for reference.
Don..
https://youtu.be/L613UOxhBdw

[dfbowers]

For those who still want to make pcb; this is by now the latest version:

I fixed a few minor things on the above schematic. Nothing major. Just what I am using on my current protoboard.
R54 - 10K
R24 - Deleted
R47 - 1K
C22 - 1uF BP
Don.

[SilverSurfer17]

From what ive read on Google it says rg58au multiple strands but id trust what you guys say if there is something better

[SilverSurfer17]

I saw the post on the three different types of cable to use ill have to order mine soon i was wondering anyone know what Minelab uses thanks or can narrow it down to whats best to use

[Mdtoday]

No Problems, I will post the project files once completed and tested.
I am going to order the REV -C Voodoo PCBs this morning.
Was not planning on going fully into George's project just yet as I am working with KingJL on his ADuM BP TX design, however, I have a little bit of a window now so will do what I can on the porting side but really would like to test on hardware.
My problem is I have a workshop full of SMD parts and only a handful of THD, so have to purchase most parts too.

cheers

Finally, I have delivery of all components, so will get on with building, testing and porting some code to XC8 compiler.
Will post code once tested.

Cheers

Mdtoday

[dfbowers]

Great news! What resistance did you chose for graphite shield and how did you positioned the drain wire in this type of coil?

I tried some generic "guitar shielding paint" that is pretty thick and coated the inside of the shell and masked off a small gap at one end. Turns out to be about 1 -2K per square. I just followed both coil channels most of the way around. The wire is held in place by the thick paint. Then a partial potting compound fill, then another layer of paint with another drain wire, then a complete second fill. It was probably the most labor intensive coil I have ever made. Seems to control the capacitance of my hand OK. I wasn't sure if the graphite paint would allow the potting compound to stick but apparently its just fine after setting up.
Wet grass will be the ultimate test! Not sure about the EMI control yet. There was some discussion of this method on the forum years ago and it just stuck in my head. Seems to be the way that the Tesoro and XP Deus coils are shielded too.

Here is a shorted link to the paint that I used:

https://tinyurl.com/y279v53b

[ionut_mtb]

While waiting for parts I just built a coil and made a few experiments based on the book material. As it turns out, it works fairly well for adding disc to a common PI circuit.

Great news! What resistance did you chose for graphite shield and how did you positioned the drain wire in this type of coil?

[SilverSurfer17]

Props to you programmers im 100 pages in and my brain is fried hence the reason why ive stayed away from it like the plague i do like that they added better search auto correct and auto complete but still all that Aa) and means the same is got my head spinning

[dfbowers]

I wish my best builds looked as good as your messy ones.

Haha.. I didn't post a pic of the inside..

[billr]

I moved my experiment off of a breadboard onto a messy prototype board and boxed it up.

I wish my best builds looked as good as your messy ones.

[6666]

Thanks for your update Don, your experiment has been very worth while and a practical application and adaptation of this new technology.

[dfbowers]

Hi Bill,

I fully understand your comments, and I did initially consider splitting off some of the conversations to separate threads. However, this leads to a lot of maintenance work that I really don't have time for.

The reality is that the book has full details of the project. In fact, more than you may even want to know. Any errors or important points noted by readers have been added to post #1, so there is no danger of missing anything. Of course, if you don't have a copy of the book, then it will no doubt be difficult to follow the discussions. But in that case, why would anyone be interested in this thread in the first place?

There have recently been discussions concerning a variant built by Don Bowers, and that's why you may see some talk about a new PCB. This is not an attempt to overcome any flaws in the original design, but just a slightly different approach. So the important point is that (for someone dropping by 1 year from now) the book and post #1 are really all they will need. If Don finds that his variant is successful in the field, then he may want to start a new thread for that particular design, but at the moment it still has relevance to the Voodoo Project.

I didnt intended to divert attention from the VooDoo project as I am working on the same project as well. While waiting for parts I just built a coil and made a few experiments based on the book material. I was kind of caught off guard when a few members pick up the idea though. Since then, I moved my experiment off of a breadboard onto a messy prototype board and boxed it up. As it turns out, it works fairly well for adding disc to a common PI circuit. It can be adjusted as to either reject iron or ferrous depending on where the sample is taken. If the sample it taken to indicate the presence of non ferrous, iron will sometimes bleed through though with slight choppy meter movements while nonferrous is usually very smooth needle deflections. I would expect that though because iron often gives a double beep on the audio. Still easy to ID iron though. I have not posted any more corrections yet as I am still tinkering a bit. If I had to change anything I may go for a faster coil, maybe try to match the frequency response of the two channels a little closer and work on a more proper way to present the disc indication. The meter works just fine but is kind of crude. Also.. the modified surf PI circuit is just what I had laying around but I think there are many better PI circuits out there..
It handles the ground just fine which was my main concern.