field test unit no 001 "model T"

[moodz]

G'day folks,

I'm new around here, having arrived with what I thought was a great open-source design idea. And a knowledge of almost no relevant mathematics (well, maybe not none, but bugger-all, as I'm dysmathic). Then I started reading this utterly fascinating thread... THen my brain exploded.

So. Now that I (and anyone else reading this thread) have bandpass-filtered the (otherwise excellent) über-knowledge from the treasure (so to speak!), we now know that moodz' original detector design is no longer in an "available for experimentation" type situation. I'm reluctant to call it proprietary, although I guess it is... Hmm. Anyway, would anyone be able to help me/us understand if there is a point in the design that we/us could use ourselves as a starting point for implementation/inclusion in our own design(s)? Without causing "issues" for the current, obviously sensational, design?

If this has already been done and is available in another thread (which I'm about to embark on reading through in any case), please accept my humble apologies! If not, can someone perhaps point me/us in the right direction?

I'm going to be coming back to this thread over and over again in the next few months, because there is so much that I find utterly significant in so many ways, although the higher-order maths is almost impenetrable to me (and I thought I was a clever clogs because I finally understood general AND special relativity!). So thank you to everyone who added so much to this amazing read. I'm truly gobsmacked. Although I note it hasn't affected my digital diarrhoea. And so I must apologise for that, too!

THanks guys, for an excellent hours' read! You just made my darn day!
Cheers,
Suitably humbled Pete the Builder

Pete ... ... I dont know how you get the perception that this is not open .. since I have published the differential coil, the frontend, the backend, the sampling in the middle and the source code. The only bit I have not published is a radical new take on coil damping , ground balance, EMI and earthfield for PI detectors ... which actually is not really suitable for differential coils .. so that is not part of this project as this is a differential coil PI thread ... ok I might be guilty of hijacking my own thread ... but I dont think that is a crime.
However if you want to build a detector dont take too much notice of everything you read here on this forum ( entertaining as it may be ) ... to quote the bard ... there is much ado about nothing. If you want a good PI detector you will need a sensor ( ie coil ), a front end to first energise the coil then receive in a repetitive manner, amplification, some sort of sampling or demodulation, a method of generating one or more pulse sources and adjusting same, some sort of indicator system .. audio / visual or similiar and a battery or power system to provide the appropriate voltages. What you wont find so easily here is a ground balance method, an earth field cancellation technique and EMI rejection methods. Lots of discussion but few practical examples. However if you are a coding wiz the EF and GB should be relatively easy to figure out.. The EMI also is not rocket science. So that pretty much sums it up .... should only take you about 4 years or so to produce a cutting edge detector ....

[Qiaozhi]

G'day folks,

I'm new around here, having arrived with what I thought was a great open-source design idea. And a knowledge of almost no relevant mathematics (well, maybe not none, but bugger-all, as I'm dysmathic). Then I started reading this utterly fascinating thread... THen my brain exploded.

Don't be so humble. You will probably find in reality that you have a superior practical understanding of this technology than many other members.

As far as the mathemetics goes, try reading Engineering Mathematics by K.A. Stroud. Many graduates owe a debt of gratitude to Ken Stroud, and his book has been described as "one of the most successful mathematics textbooks ever published". I have both first and second edition copies, and there is currently a 7th edition available on Amazon. Mr. Stroud also wrote one on Laplace Transforms, and another on Foundation Mathematics amongst others. It's like having a personal tutor, and you can proceed at your own rate. Highly recommended.

[vbeeeks]

(Post#200).....The next steps are to build the samplers / demodulators and construct the code to do the (V1 - 0.77V2 + tan(V3)) * 0.006V4 ... .... or whatever the algorithm is going to be for target extraction. -Moodz

Moodz what is that unexposed algorithm ... for the target extraction ... Is it coded and working? Is it patented or will show up sometime in the future hex? ... curiously struck me while reading and rereading the posts umpteen times. What kind of output it will give - polyphonic audio or screen alert?

[Pete the Builder]

G'day folks,

I'm new around here, having arrived with what I thought was a great open-source design idea. And a knowledge of almost no relevant mathematics (well, maybe not none, but bugger-all, as I'm dysmathic). Then I started reading this utterly fascinating thread... THen my brain exploded.

So. Now that I (and anyone else reading this thread) have bandpass-filtered the (otherwise excellent) über-knowledge from the treasure (so to speak!), we now know that moodz' original detector design is no longer in an "available for experimentation" type situation. I'm reluctant to call it proprietary, although I guess it is... Hmm. Anyway, would anyone be able to help me/us understand if there is a point in the design that we/us could use ourselves as a starting point for implementation/inclusion in our own design(s)? Without causing "issues" for the current, obviously sensational, design?

If this has already been done and is available in another thread (which I'm about to embark on reading through in any case), please accept my humble apologies! If not, can someone perhaps point me/us in the right direction?

I'm going to be coming back to this thread over and over again in the next few months, because there is so much that I find utterly significant in so many ways, although the higher-order maths is almost impenetrable to me (and I thought I was a clever clogs because I finally understood general AND special relativity!). So thank you to everyone who added so much to this amazing read. I'm truly gobsmacked. Although I note it hasn't affected my digital diarrhoea. And so I must apologise for that, too!

THanks guys, for an excellent hours' read! You just made my darn day!
Cheers,
Suitably humbled Pete the Builder

[sido]

nice guess ... But the timing on that would have to probably be nanosecond accurate given the dv/dt around the vicinity of the flyback ... The r load issue is relatively simple from a conceptual viewpoint.....it's a problem that has been solved in all engineering fields ..except pulse induction metal detectors apparently. If you are a ham radio guy you will recognise the funny side of it straight away ...us hams ... Well most of us ... Don't use resistors to match the antenna to the receiver/transmitter... It's so funny from a technical view point that it has been got so wrong for all these years and the patents with elaborate sampling schemes and pulse timings trying to correct what was missed in the first place.
moodz

Thanks Moodz, it was just a guess, but see where your refering too.

Am a bit of a Radio enthusiast and can only suggest a means of matching the TX load to a inductive matched network transformer for maximum power transfer and a ideal impedance match to the input first stage op-amp.

Using a variable inductive auto-trasnsformer as a mis-match toroid of some form.

Therefore no loss in return heat generated in a non resistive component and end result a ideal transmatch between TX and Coil to input stage at variable resistive loads that may be present.

Sid

[moodz]

Moodz, I am really guilty of raising the QED, BW issues here and then it all follows. It is really a waste of time and energy --- but someone has to defend open source spirit. Really I feel very sad for BW enterprising spirit. But this thread is an alternative to what can be done in PI technology - slowly and steadily the thing were progressing - BW and his team may come up with maybe "donate-ware" where the people interested with the BW plans may donate him for the works he produced - sure this also goes for Moodz' project as well. Maybe someday the world will all see the projects in all major electronic magazines worldwide with kits free on contest. UF & PJ - to you - well nothing to say -- I have better things to do.

I agree with you vb ..everyone should concentrate on building a complete design and spend less time ranting ... The QED from all accounts is such a machine. I have seen it working and it really is impressive.... It's a complete machine not just some ideas on paper ... Seeing it work inspired me to stop getting caught up in discussions on coils and amps and get back to the bench to complete an end to end detection system. I actually do now have a complete end to end design now .. Is it perfect .. No ... But alot of major problems have been solved with an engineered approach .. No fancy components .. Just principles and application ... now I can work on making each subsystem incrementally better ...
moodz

[moodz]

I will take a guess. You are obviously using Bi_polar Tx utilising PWM (positive and negative to zero reference) and alternatively switching simultaneously between a N-Mos and P-mos for critical damping without a R load.

Just a guess.

Sid

nice guess ... But the timing on that would have to probably be nanosecond accurate given the dv/dt around the vicinity of the flyback ... The r load issue is relatively simple from a conceptual viewpoint.....it's a problem that has been solved in all engineering fields ..except pulse induction metal detectors apparently. If you are a ham radio guy you will recognise the funny side of it straight away ...us hams ... Well most of us ... Don't use resistors to match the antenna to the receiver/transmitter... It's so funny from a technical view point that it has been got so wrong for all these years and the patents with elaborate sampling schemes and pulse timings trying to correct what was missed in the first place.
moodz

[vbeeeks]

Moodz, I am really guilty of raising the QED, BW issues here and then it all follows. It is really a waste of time and energy --- but someone has to defend open source spirit. Really I feel very sad for BW enterprising spirit. But this thread is an alternative to what can be done in PI technology - slowly and steadily the thing were progressing - BW and his team may come up with maybe "donate-ware" where the people interested with the BW plans may donate him for the works he produced - sure this also goes for Moodz' project as well. Maybe someday the world will all see the projects in all major electronic magazines worldwide with kits free on contest. UF & PJ - to you - well nothing to say -- I have better things to do.

[authere]

Not yet ... Still tuning the components but there is no sample hole .. So the detection range scales with the target size up to the coil limitations. Big nuggets should not be a problem ground balance is inherent in the technique and earth field cancellation is also now inherent and not dependant on a sampling technique. Don't sell the ML yet though.

Hi Moodz,

I have no rush to sell the M/L's as they paid for themselves 7 times over although it would be nice to get my hands on some new technology we certainly do have to be patient

Ron

[sido]

... been fairly busy with other things however the earth field rejection tests have proven successful. I realised I forgot to check the waveforms around the front end after I did the earth field mod and ( unintended benefit !!! ) the mod actually improved the "no resistor" LOL damping method. I am now getting the minelab reference coil ( actually its a commercial nuggetfinder mono coil ) to damp in 3 microseconds ( was previously around 5 microseconds which was still good ) so I picked up a couple of microseconds.
Now the pic below shows the waveform at the output of the first stage of the detector, the white trace is the mosfet gate, you can guess the rest, its not a very big target but its "tc" is definitely not near 3 microseconds and some of you will realise why my damping method is new and that the old math dont count no more. ... clue the only bit of the waveform that moves is the bit after the flyback ... and no dorothy ... I am not using a switch to do that .. only the target LOL
( maybe get ready to see alot of PI patents become old hat in 2013 ... )

[ATTACH]22737[/ATTACH]

I will take a guess. You are obviously using Bi_polar Tx utilising PWM (positive and negative to zero reference) and alternatively switching simultaneously between a N-Mos and P-mos for critical damping without a R load.

Just a guess.

Sid

[moodz]

Hi Moodz,

Did you get the can at 6' !!!, an 18" coil @1us will open up a lot of ground that was too deep for the littlies, how will this result help with the larger deep nuggets

Ron

PS:Is there much else to do cause i'm finkin i gotta sell me M/L

Not yet ... Still tuning the components but there is no sample hole .. So the detection range scales with the target size up to the coil limitations. Big nuggets should not be a problem ground balance is inherent in the technique and earth field cancellation is also now inherent and not dependant on a sampling technique. Don't sell the ML yet though.

[Aziz]

Where is the controversy action from UFox again? Or from his mates?
All aggressive actions led to improvements and better understanding.
*LOL*

Moodz, I probably know how you "damp". Quite trivial.
Cheers,
Aziz

[authere]

... been fairly busy with other things however the earth field rejection tests have proven successful. I realised I forgot to check the waveforms around the front end after I did the earth field mod and ( unintended benefit !!! ) the mod actually improved the "no resistor" LOL damping method. I am now getting the minelab reference coil ( actually its a commercial nuggetfinder mono coil ) to damp in 3 microseconds ( was previously around 5 microseconds which was still good ) so I picked up a couple of microseconds.
Now the pic below shows the waveform at the output of the first stage of the detector, the white trace is the mosfet gate, you can guess the rest, its not a very big target but its "tc" is definitely not near 3 microseconds and some of you will realise why my damping method is new and that the old math dont count no more. ... clue the only bit of the waveform that moves is the bit after the flyback ... and no dorothy ... I am not using a switch to do that .. only the target LOL
( maybe get ready to see alot of PI patents become old hat in 2013 ... )

[ATTACH]22737[/ATTACH]

Hi Moodz,

Did you get the can at 6' !!!, an 18" coil @1us will open up a lot of ground that was too deep for the littlies, how will this result help with the larger deep nuggets

Ron

PS:Is there much else to do cause i'm finkin i gotta sell me M/L

[moodz]

earth field test results update ....

... been fairly busy with other things however the earth field rejection tests have proven successful. I realised I forgot to check the waveforms around the front end after I did the earth field mod and ( unintended benefit !!! ) the mod actually improved the "no resistor" LOL damping method. I am now getting the minelab reference coil ( actually its a commercial nuggetfinder mono coil ) to damp in 3 microseconds ( was previously around 5 microseconds which was still good ) so I picked up a couple of microseconds.
Now the pic below shows the waveform at the output of the first stage of the detector, the white trace is the mosfet gate, you can guess the rest, its not a very big target but its "tc" is definitely not near 3 microseconds and some of you will realise why my damping method is new and that the old math dont count no more. ... clue the only bit of the waveform that moves is the bit after the flyback ... and no dorothy ... I am not using a switch to do that .. only the target LOL
( maybe get ready to see alot of PI patents become old hat in 2013 ... )

[moodz]

You never know just what open source detector projects with high resolution schematics,board layouts and source codes just might "turn up" on my forum!
dougAEGPF

You could start charging for membership to download .... but I reckon it needs to post on a russian site .