CTX 3030 circuit design - what's under the hood?

[Chrisdw]

Hi all I'm a metal detecting newbie and my wife just got me a CTX-3030 under the tree!
In my teens I built a Heathkit BFO unit that really never worked so I always wanted a good one.
Many treasure hunting magazines later its finally happening.

So now I am very curious to know more about what is under the hood just like a hot car.
What can you all tell me about the circuit design?
I'm an Electrical Engineer so I'd love some detail.
Has any one sketched out a schematic or a higher level diagram?

I understand that it has an NXP/Freescale ARM 9 core running Linux.
What is driving the output coils and monitoring the receive coils?
Any fancy Analog to Digital Converters (ADC) involved?
In my work I design hardware for Electrical Power Quality Meters that I expect share some features.

I do have a Metal Detecting friend who promised some guidance, and there are clubs in the area.
I hope to pick up that new ML book and a Pro-find 35 when it is available.
Lots to learn!

 

[Jason in Enid]

Nobody here will have a clue about the inside workings. The best (and only) info you can get is from the Minelab website itself, but even thats not going to answer the questions posed.

 

[IDXMonster]

What’s under the hood? A really mean mother,that’s what! Along with that there is a boatload of proprietary technology that you won’t get the key to in any way shape or form.
To be curious about the internal workings,while heady,isn’t why people have a CTX. They have it knowing it’s one of the best tools available to do a certain job and that’s to find deep coins and sometimes difficult coins.,and of course whatever else you’d be after.
Just be thankful that you have a really really giving mate and leave the rest to the engineers that have put this marvel of technology together. To question anything it’s doing,while heady,isn’t going to gain you anything in the field. What WILL gain you EVERYTHING in the field is to go use it. A lot.
Merry Xmas to you! If you have questions(the kind we can answer)...ASK!

 

[Chrisdw]

Thanks

 

[sgoss66]

Chris --

I can totally appreciate your approach. I'm a scientist, and the "why" and "how" questions are always first and foremost in my mind, about EVERYTHING. But, what you are asking is quite proprietary, and Minelab offers very little of the info that you are searching for. However, here's at least "something," to give you some basic idea of how Minelab approaches things...

https://www.minelab.com/__files/f/11043/METAL%20DETECTOR%20BASICS%20AND%20THEORY.pdf

Meanwhile, as several here have said, your wife just gave you a most AMAZING gift -- a machine that many consider to be the top coin-hunting unit on the market, and the flagship machine of one of the best, most widely respected detector companies in existence. If you take the time to learn it, you will be rewarded immensely. Don't get frustrated, it's a marathon, not a sprint (learning the art and science of metal detecting). There are plenty here, who can help...

Merry Christmas!

Steve

 

[Chrisdw]

Steve - thanks for responding. I just want to know the pieces like opening up your cars hood and seeing that it is a V6, double overhead cam, turbo with fuel injection and coil per spark plugs design. You can see these details by looking at a pcb and reading the IC names and generally how they are connected. I do not see that as proprietary. I visited the geotechnical forum in hopes of learning more. I will review your link. Yes she is amazing. This should be fun.

 

[sgoss66]

Chris --

Gotcha! So, you just want to know what pieces and parts are used...

Yes, you are right, that part is not "proprietary." Not sure anyone on here has disassembled one, but I'm sure someone has, somewhere. Wish I could help!

The Geotech forum has plenty of folks who are into building their own machines, so they are a much more "technical" crowd, in terms of the actual electronics. The link I gave you is more about how detector theory, and hints about Minelab detectors and how they function. But no "nuts and bolts" in there, in terms of components used on the PCB, etc.

Steve

 

[Chris(SoCenWI)]

They are probably the best documents available,

 

[GKMan]

Maybe these guys had figured something out about it..

Hacking the CTX or something along those lines was the name of the thread
http://www.findmall.com/read.php?86,2358112

 

[Chrisdw]

The most proprietary piece of any embedded design is the application firmware.
I'm not going there, but i do want a feel for what horse power we have in this machine.

Think of a PC, you typically know what Processor it has, what clock speed, how much system and storage memory.
If your a geek like me you might take a look at the chips on the board that support PCI etc,
This is the hardware platform that you can see just like looking under the hood of your car.

An ARM9 is a solid motor that is very capable or running our machine.
The receive signal is small so a nice differential op amp would help isolate the signal and feed into perhaps a fast Delta Sigma converter.
With the right combination one can get very good signal to noise ratio (SNR) and reject much of ambient noise.
That is the sort of detail I was looking for.

The ARM9 has been around for a bit but is heavily supported in the linux world and will be supported for a long time.
Check out http://beagleboard.org/bone.

I am curious to know what the latest ML Equinox machine is running.
There are some great dual core - ARM8-15 and Digital Signal Processors to consider.
The ARM would run the user interface and the DSP the detecting, well that is how I would do it.

With the snow on the ground it will take a while for me to use the detector.
So in the meantime I will investigate what is under the hood.


,,

 

[Mr. Carolina]

Chrisdw. Just be glad your wife bought you a CTX and not a Equinox or else your tree would be bare!!! I don't think you are going to find any answers that you are looking for unless you can find a CTX for sale for parts only and tear it apart yourself. I have never seen one of those yet though so I would do my best to calm your curiosity and put your energy into learning the CTX. I feel sure the firmware application is what makes it tick and that you will never see. If you search for the patent you will not find one as Minelab did not want to give any clues away of it's design, so they did not patent. The most important thing I can tell you is pay attention to your gaskets and care of your machine. Buy a screen protector for the screen and if available, attend a boot camp by Andy Sabisch to speed things along. Good luck to you, and go outside and dig up your lawn!!! MERRY CHRISTMAS.

 

[IDXMonster]

The biggest thing seen for quite some time as the “blockage” to getting depths WITH ID is the ground matrix itself. It’s not about more power,there’s are formulas and decades of physics that have been done by really really smart people who do this for a living. Not to be a Grinch,but for the first post to be about how you are going to crack open the CTX and make it better in some way to me,well....sounds a bit aloof. IF you are really anticipating going detecting and doing it because you like detecting,that’s one thing. The CTX will do you well.

 

[Chrisdw]

Dxmonster- reread my original post. Never said anything about hacking the machine. Instead one of understanding/appreciating the hardware platform. I've always been curious about how things work. When I buy a car I want to know all about it engine, transmission, suspension etc.. Same goes with electronic devices. As an Electrical Engineer i don't see this as a black box, but much like the car with the core processor being the engine and the analog to digital convertors as the transmission and so on. I'm sure some off you can relate.

 

[Jason in Enid]

Dxmonster- reread my original post. Never said anything about hacking the machine. Instead one of understanding/appreciating the hardware platform. I've always been curious about how things work. When I buy a car I want to know all about it engine, transmission, suspension etc.. Same goes with electronic devices. As an Electrical Engineer i don't see this as a black box, but much like the car with the core processor being the engine and the analog to digital convertors as the transmission and so on. I'm sure some off you can relate.

(EDIT) Broken ones go up as "parts only" salea every once in a while. One of those would sell pretty cheap and it would be perfect for you to tear into and see how its made. You could probably enlighten us on aspects, like what chip is in the coil and what is its role.

 

[bklein]

I’ve never seen a dead one for sale.... what have they sold for?
It would be a cool project to figure out the coil interface so we could experiment with coils.

 

[Jason in Enid]

I’ve never seen a dead one for sale.... what have they sold for?
It would be a cool project to figure out the coil interface so we could experiment with coils.

Its not often but I have seen a few over the years. I don't remember the final price, but search through completed auctions could probably root them out. I think they end up going for a couple hundred because people are hoping its just a dead PCB and they can re-use/re-sell coil/face pad/battery/stems

 

[Chrisdw]

I suspect that the chip in the coils is both an identification and calibration memory chip.

 

[IDXMonster]

I suspect that the chip in the coils is both an identification and calibration memory chip.

Chris-AFAIK the chip is for signal conversion. This makes for a “cleaner” signal to and from the coil by cleaning up possible interference coming through the cable itself. It’s digital TX to the chip,analog from chip to target and back to chip,and then digital RX back up to the machine. There very well could be other things embedded in it for various reasons but as I understand it,signal converting is its main function.

 

[bklein]

I have obtained a test coil but not sure it is bad so not opening it up just yet. If anyone knows I'd like to know if the board is encapsulated in epoxy and where in the housing it is.

 

[trojdor]

My understanding is the same as described by IDXM.

Additionally, I've heard references to an accelerometer...to determine sweep speed.
(Whether it's actually/really used...I don't know.)