field test unit no 001 "model T"

[moodz]

]Sigh. I've been dipping into various threads in this subforum, and I could've sworn I saw a comment saying the design was now unavailable. I will go through my history and verify. I'm delighted to hear it's alive and kicking. I'll dig through and collate the info, now that I know it's all there. Thanks!

I'm just smart enough to know just how "easy" it is to do all that you suggest - and how hard it is to get working! I started off with grand ideas of a simple (ha!) mode-switching detector based on a fairly cheap/powerful MCU, with a simple (ha! again) front end and amp, with straightforward sampling and curve fitting and... Once I worked my way through the history of PI, and saw many of the patents, and saw how many *real* engineers had spent so much time in this field, I realised that with my maths "skills", I needed to rely on other people's approaches to the problems. I guess that's one thing I'm actually really good at, being able to patch together various designs without breaking, faulting, or letting the smoke out. I love doing it, and I learn, too - win win!

I can code (I've been doing it for a living, on and off, for 30+ years, admittedly mostly DOS and windows (and now macintosh) high-end stuff, but I've kept my head above water technically with the micros (I still have working Z80 systems, which is sad, I guess!), but again, my poor maths grasp lets me down. Show me a matrix and a dot or cross product term and I start sweating and losing hair... Hell, I've been working on a Kalman filter for about 3 weeks for another project, and I had to stop and go to iTunes university for a refresher course on matrix maths - then I discovered I needed linear algebra, so that was another course, then I realised my fractions were terrible, so I've gone back to primary school courses to try and pick it up again. Did I mention I turn 50 this year? My brain is full of things I don't need...

Anyway, thanks very much for taking the time to respond so fully. I've learned more from this forum in a day than I've gleaned in a week on my own. So kudos, dude!

ahhh we will have to swap notes one day ... I have a dual core z80 design running at 300 Mhz in an FPGA ... adimittedly on a backburner as I am not sure what to do with it .... however the ole Z80 aint dead yet !!

[Aziz]

..
There is a certain satisfaction in knowing something that no-one else knows ( at least to my knowledge and research).
..

There is a certain satisfaction in knowing something, that someone believes, that no-one else knows.
*LOL*
Clue: Some processes are reversible.
Aziz

[Aziz]

The maths for PIs including target reponses is hellish .... better to forget it ... I suspect it is incomplete. Clue ... if you want a top machine ...there is a schematic on the web ... search on QED .. there is some info here at Geotech but more elsewhere ( cant say exactly as there is kind of a civil war involved about it as well ... and I dont mean Intellectual Property related ... ). This design is as good as or better a performer as machines costing $7400 more .

Bl00dy h...!,
doesn't it cost $6500 anymore?
Is that the Greed-factor or the Gold-tax? Or the Rip-off-factor?
Aziz

[Pete the Builder]

OK, I'm still catching up, but I'm starting to see what you mean about the potential of the "Moody Über Damping Self-Limiting Induction-Nullifying Gyroscopic Elimination Rig" ^_^

Anyway. It's late, I'm on the iPad, and I still have catching upping to do. Hope you liked the acronym!

[vbeeeks]

Excellent effort, but did you think of introducing ferrite core as your differential monocoil (bifilar) does not respond to ferrite as such - or put another way - how will it effect the total scenario put down till date, if introduced? - my point is toward pin-pointing and miniaturization/down-scaling... "lite" is what they call... but sure my call is towards hunting river sand - or more so towards the old timers - a rectangular monocoil for sluice sieves type hunting - I don't feel that an idea worth "instructables". Anyway your algo starts and ends with Tx pulse and a 50us window everything else is a function and some are variable some automatic as much as I can understand.

[Qiaozhi]

]Anyway, thanks very much for taking the time to respond so fully. I've learned more from this forum in a day than I've gleaned in a week on my own. So kudos, dude!

Warning ... blatant advertising coming up ...

I assume you've seen this while trawling through the various forums ->
www.geotech1.com/itmd

[6666]

Hi Moodz
is your new invention based on ready made commercial coil ?
and do you still use a ferrite choke on the coil cable ?

[moodz]

Hi Moodz
is your new invention based on ready made commercial coil ?
and do you still use a ferrite choke on the coil cable ?

Hi 6666 .... Yes I use standard commercial minelab type mono coils for testing so it needs no special coil .... It will also work on DD and other coil types. this is good because people wont have to buy a new coil. I don't use a ferrite choke .... That was for a different problem. All this invention does is auto ground balance, EF cancel, EMI reject, increase sensitivity, damp 2 or 3 times faster and not based on prior art ... Not much at all really .

[6666]

Hi Moodz
thanks for that, what are you future intentions
how will we be able to obtain your invention once all the "paper work" is done ?
will it be sold as a ready built device ?
cheers
6666

[moodz]

Hi Moodz
thanks for that, what are you future intentions
how will we be able to obtain your invention once all the "paper work" is done ?
will it be sold as a ready built device ?
cheers
6666

If the patent goes OPI ( Open for Public Inspection ) then you will be easily see how it can be done as it is based on a method and principle. Needless to say there is no damping resistor As for sale ... I will be in Europe and the US in March then on to China in April .. we will see what eventuates ... hint the fast damping of sensor inductances has much wider applications than the relatively "niche" detector market.

[6666]

Thanks Moodz
cheers.

[Aziz]

Once again:
Its the end of Greedlab!

*LOL
Aziz

[vbeeeks]

What has frequency sweep (10KHz ..20Khz) on Tx pulse, to do with discrimination?

[moodz]

What has frequency sweep (10KHz ..20Khz) on Tx pulse, to do with discrimination?

I thought I mentioned sensitivity ... not discrim. The new damping allows much faster PRR ( pulse reptition rate ) ... you can still use slow rates too. .... and its not a sweep though that is an interesting investigation.

Regards.

[moodz]

...good news everybody .... I have thrown the discrete Earth Field filter out of the circuit and using a "tricksy" variation of the same technique that achieves fast damping and autoground balance the EF problem is now resolved .... field test results soon. This was the last hurdle on the front end .. the presence of the Earth Field filter caused some reduction in sensitivity.
Transmit coil voltage is now set at 6 volts with 1.6 amp peak current and pulse repitition of 5 Khz and 2.5 us damping on the excellent "Nuggetfinder" Coil. There are no target holes and no EMI issues.