NEW !!! Full differential PI front end.

[moodz]

FPGA progress and EMI reduction.

posted in

http://www.geotech1.com/forums/showthread.php?p=111143#post111143

moodz

[Rov]

Yes Andygold,Bills plugger rods,look hard to beat at these prices,Thanks!

[Andygold]

Detector stems

Also check out Bill Quinn from Plugger rods in California. He makes excellent stems with quality handgrips and stands from only US$68. Easily a match for Andersons but only half the price. You'll find him on Ebay USA.
Cheers, Andy

[Rov]

PM sent Ian.

[IBGold]

Rov,
Would you let me know the manufacturer in Adelaide as I will be there next week and if time permits I might be able to check out what they have and report back to Moodz as I thought he was in Adelaide as well but now I see he is not I probably know the company anyway and have probably dealt with them before as Adelaide is a small place business wise, You can PM me if you like.
Regards, Ian.

[moodz]

Thanks Ian .... I have been toying with the idea of using a modified crutch as they have the right ergonomics and come in pairs at a reasonable cost. I would have to replace the lower section with a non metallic shaft.
I will investigate the Adelaide connection ... thanks Rov.

Moodz.

[IBGold]

Hi Moodz,
I cant help you with the shafts the only ones I have played with are the Otto ones for obvious reasons but I think it may be to your advantage to contact Rov's suggested supplier and see what they can offer they may be the same supplier that made the original Goldseekers ones I owned a business in Adelaide in that field until I sold up and retired in 2004 but it is not rocket science I would suggest fibreglass shafts give Western Fibreglass a call and see if they can help If I think of any other I will PM you.
My Electronics knowledge is not great I have been a ham since the early 1970's (VK5KIB) but only know enough to be dangerous Hi but if I have the layouts I can build it but the new technology is over my head.

Tinkerer,
I have read your other post and will reply there when I get a minute it will be something different to try all my forms are for elliptical or 3 to 1 rectangular either mono or DD but I do have one round one of 325 OD and I like a challenge.
Regards, Ian.

[moodz]

Easier than you think.

All this FPGA stuff seems terribly confusing for some hobbyists .... even though this whole project is coded in VHDL ( hardware description language ) ... you can look at it as a schematic ... and you can actually edit the schematic and not write any code at all if you want to.
Below is the actual schematic for the TMPI project that is the FPGA backend .... This particular schematic was drawn automatically from my code. ...each chip is a code module and the wires connecting it are signals that are defined in the code. You can expand each "chip" into a sub schematic till you get down to gate level ( AND, OR etc ) The main "chips" in this schematic do the VGA function for the scope, the filters, Freq counter, LCD control, pushbuttons, filters, 32 bit CPU, ADC control and memory controller. All these "chips" are programmed into the FPGA chip.
All the VHDL code does is describe the connectivity and behaviour. Each time you write a block and connect it to others a new "chip" will appear on the schematic. So if you are used to working with schematics and chips its not that hard....

Mooodz

[moodz]

FPGA progress

... adding the first filter bank for ground balance .... below are traces from the built in scope funtion showing the TX pulse ( yellow ) the input signal ( purple ) the target signal ( white ) and the reference ( red ) I have demonstrated a target showing how the target signal white moves away from the red reference. Note how the digital filters have extracted the clean reference ( red ) from a very noisy input .... cant even see it on the input signal ( purple )... that is one smokin filter even if I say so myself.

The input signal is depends to some degree on the TX pulse, the target signal is derived from the input signal and so on.

The red reference is the equivalent of sampling with a 28 bit ADC ... moodz filter function .. and to think I hated maths at school.

This milestone shows a number of things ....
1. all four channels are working correctly on the built in scope function
2. sync lock is rock solid
3. the filters work better than I expected.

Moodz


NO TARGET below


with TARGET below

[Rov]

Hi Paul,custom made from a batch local.
they use lightweight metal tube with twistlock extention,alloy armrest,plastic T an grip.have a Bill Hayes made insert for coil at the end.Have used these even to fit ML an other detectors to the pole/stem assembly with Chrome springclips or caphead machine screws.some have the handle assembly inclined 30degree forward for better balance.
regards Rov

[Tinkerer]

Coils for TMPI

Hi Moodz,
I like the way you are going about your design will you be making available the coil design specs when all completed as I build all my own coils I live over the water from you on the peninsular.
Regards, Ian.

Hi Jan,

Moodz has given the TX and cycle times as TX, 127uS and cycle 512uS. I am starting to build a coil for this.
Since you are a very experienced coil builder, you are probably well aware that it takes a few tries to get the perfect coil for a specific detector.
If you (and others) are interested, we could each build some coils of different sizes, designed for the TMPI, exchange information and compare results.
We would quicker reach the goal of a perfect coil.

As a starter I suggest:

DD coil of 30cm diameter
Concentric IB coil of 30cm diameter
concentric IB coil of 45cm diameter

There are many factors to be taken in account. Coil wire, coil cable, shielding etc.

I am posting information and pictures on the 45cm coil at----today.

http://www.geotech1.com/forums/forumdisplay.php?f=53

Any suggestions are welcome.

Tinkerer

[moodz]

how about this,is a simple pole/stem assembly with a twist lockextension,as used for PulseMate PI detectors here in Oz.Pm if you interested in one Moodz.they made in S.A.as well.even to small lots if required.
regards Rov

Hi Rov what are they made of. All plastic or top metal bottom plastic. Who stocks them or are they custom made ?
Thanks for the info ... much appreciated.

Regards,

Paul.

[Rov]

how about this,is a simple pole/stem assembly with a twist lockextension,as used for PulseMate PI detectors here in Oz.Pm if you interested in one Moodz.they made in S.A.as well.even to small lots if required.
regards Rov

[moodz]

Hi Moodz,
I like the way you are going about your design will you be making available the coil design specs when all completed as I build all my own coils I live over the water from you on the peninsular.
Regards, Ian.

Thanks Ian ... I dont have any secret coils so I see no reason why not .. I am still doing alot of work in the coding department ... and as I dont have an example to copy some of it is new ground ... In the background do you or anyone know of anyone selling the shaft to hold the coil and the bit box ... I found this product which looks cool ... not sure if there is a dealer in Oz .... http://www.andersondetectorshafts.com/27.html
Moodz.

[IBGold]

Hi Moodz,
I like the way you are going about your design will you be making available the coil design specs when all completed as I build all my own coils I live over the water from you on the peninsular.
Regards, Ian.