WANTED: Someone to write an 'Oscilloscopes' tutorial on Detector and Coil tuning, - Willing to pay -

[MartyJ1963]

Hi all,,,,,Some people may say,,''Search the Forum',,'Buy ITMD and read that,,' ( A brlliant book that I already own),,etc,,,to the question I'd like to ask here,,but I desperately want to learn how to how to use an Oscilloscope strictly for Detector buildng (Debugging),,and especially Coil building ('DD'/Concentric/Mono). A lot of people will tell me that there's plenty of information here on the forum covering the subject, and believe me when I say that I'm on here everyday reading and re-reading, copying/pasting information that I've collected for my own notes, and I'm still struggling to use the Oscilloscope. Two days ago, I bought a Hantek DSO5102P 100mhz scope,,I thought I'd upgrade from the Oscilloscope that a good friend of mine lent to me for learning on (A hantek 6022B) hoping this would be a better device for Detectors. As you know, many of the electronic devices come from China and their instruction manuals aren't the best and there's not many tutorials around to learn from. Anyway,,,the main thing I'm wanting is someone, who has the time, knowledge and patience to write a conscise tutorial for me and how to debugg a detector and tune coils coils up using an Oscilloscope/Multimeter, and I'm willing to pay that someone for his/her time for the information. This 'Tutorial'/'Guide' etc would not only help me, but would also help all the countless others/newbies here on the forum. Like I say,,,If anyone here on the forum is up for the task, I'm willing to pay them for their time to do this for me. I've learnt a great deal from Geotech since I joined 2-3 years ago,,,this forum gave me a brand new Hobby and Interest in my life and really has become very important to me. People like Silverdog (Andy), Qiaozhi, amongst many others, have helped me many times with my questions/problems etc and I'm grateful there are people 'Still' out there willing to give their time/knowledge etc for free, and though I've thanked them many times I'd like to say thanks to them again. Hopefully, one day, when I know enough, I'll be able to give something back and help others too. This Forum has so many knowledgeable people/members that I'm sure there must be at least one person out there with the patience and skill to be able to write a conscise little manual/tutorial (Like DFBowers did with the TGSL coils etc,),,,and I'm willing to pay them for it. Any takers?,,,,Thanks all. Marty

[MartyJ1963]

Hi all,,,Just to add to the above post,,,,I've built about 25 detectors up till now,,mostly P.I's,,but I have saved all my finished VLF projects for something to do in the winter months. I have 2 x IDX, 1 x TGSL, and 1x IGSL that are all working etc, but have not been able to tune the coils for them. IE:- I don't know how to tune them correctly. I have made the coils for them all,,1 x concentric and 1 x DD for the TGSL,,1 X Concentric and 1 x DD for both IDX's and 1x DD for the IGSL. I have checked and doubled checked all my inductances and resistance and they all seem to be correct but I can't get any further till I learn the Oscilloscope. Hopefully there's someone out there with the skill and time to write a good tutorial on how to do this and I'd be forever grateful. Thanks agan. Marty

[nonkapo]

Good topic. About the Metal detector specific measurements you can gain some info from the Geotech Mini Pulse Plus, Barracuda and Hammerhead project manuals which can be found in the related project forum threads. For a general info i would recomend you google and You tube - the links below. I know these are for dummies but you may find them handy. It will be adwisable to share what unit do you have.
https://www.youtube.com/watch?v=R3fZcQjGMPI
https://www.youtube.com/watch?v=u4zyptPLlJI

Regards

[kt315]

your request is absolutely right in time. no specific information around on how to right tune coil. i see much suggestions in russian forum
but not here (no specialists of high level wishing to share the info with pics and graphics).
also, Zakrzhevski had changed the rules of forum and unregistered members do not see attached pictures now.
so we losed the opportunity to take schematics and pics from it.
there are also different designs of VLF coils around
- tesoro, simplest, unresonance
- whites, parallel resonance,
- garrett, with pot tuning balance
- minelab DD, with preamp and backing loop on preamp

you may look those videos, but never will see how they tune a coil
https://www.youtube.com/watch?v=6adQvxOugcU
https://www.youtube.com/watch?v=0hGTZBBpHBs
just naked bla bla bla. the info is sure covering up.

[ivconic]

Hi all,,,Just to add to the above post,,,,I've built about 25 detectors up till now,,mostly P.I's,,but I have saved all my finished VLF projects for something to do in the winter months. I have 2 x IDX, 1 x TGSL, and 1x IGSL that are all working etc, but have not been able to tune the coils for them. IE:- I don't know how to tune them correctly. I have made the coils for them all,,1 x concentric and 1 x DD for the TGSL,,1 X Concentric and 1 x DD for both IDX's and 1x DD for the IGSL. I have checked and doubled checked all my inductances and resistance and they all seem to be correct but I can't get any further till I learn the Oscilloscope. Hopefully there's someone out there with the skill and time to write a good tutorial on how to do this and I'd be forever grateful. Thanks agan. Marty

Sometimes immediate environment with current conditions in which coil balancing attempt takes place can drastically hamper and even completely disable successfull balancing.
Although seemingly minor; this can often be a major cause of fails.
This is rarely emphasized and indicated, because it belongs to the basics of things that go without saying.
Closest environmental conditions must be met before anything else.
Meaning further that there should be no metal in vicinity of coil which is about to be balanced.
Also same applies for any kind of natural or artificial source of hums, interferences, strong magnetic fileds etc.
Working environment should be "clean" from such factors.
Proper two-channel osciloscope, preferably "digital" one, is ultimate instrument for this and similar tasks.
But not mandatory at all.
Especially not for common diyer.
Majority of mentioned diys are pretty tolerant in specifications and coil balancing for them should not be a problem, even without any oscilloscope.
Probably the best "poor man's" solution for very accurate coil balancing is the Andy Flind's method, described in his "Magnum" articles.

[dbanner]

Problem ain't with coil "balancing", this is trivial. Big problem is keeping this perfect "balance" while potting. Therein lies biggest challenge.
Concentrics present a different challenge altogether. Their geometry is very unforgiving when it comes to number of turns, however you can easily get it to "balance", even if the Rx if slightly off center. No potting issues with concentrics.

[ivconic]

Problem ain't with coil "balancing", this is trivial. Big problem is keeping this perfect "balance" while potting. Therein lies biggest challenge.

Pretty correct.
It is good to add also a fact that "double D" coils are harder case comparing to concentric-coplanar ones.
It is easier to maintain good balance on "c.c" coils with feedback coil included.
Or with some kind of "electrical balancing circuit" additionally added to/inside the coil.
Double D (or DD) coils are tougher in this aspect.
Potting with epoxy is carrying one important "side effect" which should be especially emphasized.
Epoxy tends to produce significant heat in moments of hardening.
The heat is directly affecting wires in coil, making them to constrain and finally destroys the electrical balance.
There are types of epoxy. "Fast" and "slow" ones. "Hot" and "less hot" ones. Etc.
I am not chemist and i can only divide types like that.
Ideal would be "fast" and "less hot" epoxy for potting the coils.
Also; today most of the diyers are simply striving to "DD" diy coils.
Because those are generally "deeper" coils. A much harder task though.
Seemingly those are easier and faster to make, in reality those are more demanding to finish them properly and maintain good balance at them for longer period of time.
Concentric coplanar coils are better choice for diyer. Although it seems a bit more demanding and complicated to establish working setup for producing such coils.
Of course; all this speaking strictly from diyers standing point.
In industry things are much more simplified and easier.

[dbanner]

Yes Guru, I agree. Epoxy is enemy of electrical null. Or maintaining any sort of "balance".
As for concentrics, what I would love to see is a coil shell kit, where the spools are included for winding the TX and RX and bucking coils, with fasteners to set them in place.

[ivconic]

...
Probably the best "poor man's" solution for very accurate coil balancing is the Andy Flind's method, described in his "Magnum" articles.

MartyJ1963 started very interesting topic by asking very interesting and important question.
I seriously doubt that anyone from the "pro"s here will offer complete answer.
Though it is splendid idea for the book writers here to consider this as additional chapter for some new book.
But shortest possible answer to his question would be what i quoted above.
Just read Flind's articles and act accordingly.
Oscilloscope would perfectly replace Flind's helping circuit for coil balancing.
I like to keep things as simple as possible, so i am mostly using that circuit and ordinary "VU scale" for balancing.

[MartyJ1963]

Hi to all,,,,First of all thanks to everyone for the replies so far. @Nonkapo,,I have, literally, a folder full to the brim of Video clips, tutorials analogue/digital, written articles and Oscilloscope courses (16GB in total), and not one of them have taught me anything in view to Tuning and troubleshooting Metal detectors or Coil tuning. I search all the time and haven't found anything yet. @KT315,,you are absolutely right,,there is not enough information circulating that specifically deals with the aspects of this subject,,IE:- different coils/designs/inductances/methods of tuning etc. I really respect your the work and the help and knowledge you have shared amongst the Geotech community as I do with many other people on here, and if you're willing to write a detailed article on this subject I am willing to pay for it. I know sometimes you have difficulty in translation when discussing certain things like we all do sometimes, but I am willing to help with the translation as much as I can. Especially for newbies, like myself, if for instance you wrote the steps like this,,,Step 1. Place CH1 probe at the comparator,,,Step 2. Place CH2 Probe at the pre-amp output,,,etc,,,a lot of newcomers to the hobby may not know what a 'Comparator' or a 'Pre-amp' are,,,,I'm still learning what some IC's are for and what they do and there are a lot more people out there who know less than me. A 'Clear', and conscise-step by step guide would be a great help not only to myself but to others who want to begin this brilliant hobby from scratch,,,not knowing, and not being able to find available information can be disheartening and it puts a lot of people off,,,,@dbanner,,,please don't take offense, one of the biggest problems, to me, 'is' coil balancing and I don't think it is so trivial. I've noticed a lot on the forum that some people have got to the point where they think they've balanced the coils properly, with and without the oscilloscope, and then just gone right ahead and potted them. Later, then, some have found that they over wound the coils and the inductance/frequency was totally wrong even though it may have detected metal ok at first,,,then they've had to start again. You are correct though about the coils going out of tune during the potting procedure,,,If one could learn the correct procedure for coil tuning first then they can learn the correct potting procedure, through trial and error/different potting compounds/slow curing/fast curing etc,,second. I have become better at making a detector now that works straight away from first switch on that it's made me now more determined to get skilled in coil making and the use of an oscilloscope,,,Hopefully someone can write me a well described tutorial to better my learning and I'm willing to pay them for writing it for me cos' I'm 'that' serious about learning this Oscilloscope subject. Thanks everyone. Marty

[green]

Don't know if other scopes have the problem I think I have with mine. I think my scope gives bad output if I set the input scale to low compared to the peak signal input. (Example)Rx coil decay,amplifier saturates at 2.5 volts, signal looks good with .5 or 1v/div. If I try to look at signal after it has decayed to a lower value with scale at 100mv/div I think I get a bad reading.

[Hyena]

Hi Marty, I just think that metal detector is not a good starting point how to learn absolute basics about electronics...

[ivconic]

Hi Marty, I just think that metal detector is not a good starting point how to learn absolute basics about electronics...

And coil balancing subject to place in front of the basics is like building house by starting from a roof.

[MartyJ1963]

Hi Hyena,,,The information I'm actually looking for is to be specifically using the Oscilloscope mainly for coil tuning, not just the electronic side of Detector building. I am confidently able to print and etch my own pcbs, redraw/redesign pcb's in Sprint/Diptrace, and solder more skillfully,,,I've built about 30 Detectors up till now,,PI's, VLF's,,,after the first 6 I built, which had minor mistakes etc, all worked from first switch on,,,,I have no trouble with making Mono coils to an exact inductance and resistance, it's the DD's and Concentrics I want to become better at now. I'm after someone to write me a Tutorial/Guide specifically on where to place the probes and what to look for on the screen regarding waveforms/written data,, IE:-Frequency/pulse width/1st sample/2nd sample/flyback etc,etc,,,I don't have a clue how to do any of that and even after constant searching and collecting the info I can (16GB) I haven't come across anything that even scratches the surface. Thanks. Marty

[dbanner]

Hi Marty, your topic is extremely important, I didn't mean to make it seem trivial. What I meant was RELATIVE to "potting". In other words, if you think balancing is hard, then potting the damn thing can be even more challenging! A nightmare when epoxy hardened, and the null is off, the thing is rendered useless. An absolute disaster!
Andy flind's method is excellent for nulling, but not for seeing phase displacement of Rx vs TX waveform. For this you must have oscilloscope. Depending on what type of circuit you are doing, "off resonance", parallel resonance etc.