King Cobra PCB

[kt315]

from all pics i choiced those

[Merc]

Is it the plastic holders for the AA cells that have broken or the wires to the PCB? Those holder area available.
https://www.ebay.com/itm/6-Volt-DC-B...kAAOSwT6pVxow1

[kt315]

Friend i make king kobra not oregenal . The other pcb . I well make it again please witch of them making the oregenal or simple king kobra.

anyway you can give pics. my name not Yeshua Ha-Nozri to see at distancy what you do there. i'm just kt315.

[sbalio1]

Hi all friends ennyone here help to give me the right pcb for print king kobra i just finish it but it dosent works with me it give the noise please help .

[zamat940]

Hi All
file King kobr .pcbdoc

pliease help

[mouh]

First experience

First experience for beginners like me
Thanks to everyone for this great forum and special thanks to "kt315" who advised and helped me
This is my first experience on this forum
I'm trying to make a "king cobra" metal detector.
These are the first pictures of the PCB
I will complete it this week

[sbalio1]

hi mouh i was alredy made this type king kobra but it doesent works with me .

[mouh]

Hello sbalio1
My friend, I am still working on this project
When you're done, I'll give you a result

[sbalio1]

ok friends im waiting.

[kt315]

Melbeta wrote. may be usefull for you.

I was looking into some files, and I found this brief concise, explanation of how a VLF detector uses PHASE SHiFTING in order to accomplishing discrimination and/or analysis of a target, and it really shows a person the fallacy of precision discrimination methods of a metal detector. Thus my statements here in postings that relying upon discrimination to accurately tell you what the target is really is a bunch of guess work. Discrimination is clearly telling us that ALL DISCRIMINATION of a VLF machine, is BASED UPON PHASE SHIFT of the target! Not because it is a silver coin, gold coin, silver ring, gold ring, penny nickel, dime, quarter, pulltab, nail, etc, etc.... and it tells the discrepacy depends on inductance and resistance of the target. That is why your meter says it is a coin and it ends up being junk target!!!

And like I said in past postings, they use filters and other things to get rid of some kinds of trash, and likewise that gets rid of good targets which you would really like to find!!!!!!!!!!!

What does this article REALLY TELL US???

It says that what I said again and again and again WAS REALLY TRUE!!!!!!!!!!!!!!!!!!!!!!!! And JOE CLARK, here it really explains your questions!!!!!!!!!!!! The old machines without this crap work better. They might not be that great with mineralized soil, but they damn sure work more accurately!!!

Merry Christmas and a Happy New Year, you just read the truth, the whole truth, and nothing but the truth!!
Melbeta

VLF Phase Shifting

How does a VLF metal detector distinguish between different metals? It relies on a phenomenon known as phase shifting. Phase shift is the difference in timing between the transmitter coil's frequency and the frequency of the target object. This discrepancy can result from a couple of things:

? Inductance - An object that conducts electricity easily (is inductive) is slow to react to changes in the current. You
can think of inductance as a deep river: Change the amount of water flowing into the river and it takes some time
before you see a difference.

? Resistance - An object that does not conduct electricity easily (is resistive) is quick to react to changes in the
current. Using our water analogy, resistance would be a small, shallow stream: Change the amount of water flowing
into the stream and you notice a drop in the water level very quickly.

Basically, this means that an object with high inductance is going to have a larger phase shift, because it takes longer to alter its magnetic field. An object with high resistance is going to have a smaller phase shift.

Phase shift provides VLF-based metal detectors with a capability called discrimination. Since most metals vary in both inductance and resistance, a VLF metal detector examines the amount of phase shift, using a pair of electronic circuits called phase demodulators, and compares it with the average for a particular type of metal. The detector then notifies you with an audible tone or visual indicator as to what range of metals the object is likely to be in. Many metal detectors even allow you to filter out (discriminate) objects above a certain phase-shift level. Usually, you can set the level of phase shift that is filtered, generally by adjusting a knob that increases or decreases the threshold. Another discrimination feature of VLF detectors is called notching. Essentially, a notch is a discrimination filter for a particular segment of phase shift. The detector will not only alert you to objects above this segment, as normal discrimination would, but also to objects below it.

Advanced detectors even allow you to program multiple notches. For example, you could set the detector to disregard objects that have a phase shift comparable to a soda-can tab or a small nail. The disadvantage of discrimination and notching is that many valuable items might be filtered out because their phase shift is similar to that of "junk." But, if you know that you are looking for a specific type of object, these features can be extremely useful.

[kt315]

see it on ebay...

[Melbeta]

see it on ebay...

I started out with old BFO machines. Then I found a BFO with a meter that said good or bad. I used that until I found the Compass Yukon Professional. I am a Compass guy. I do not like to use discrimination. I find more using all metal mode. But I dig more too.One has to be patient and try to dig each target. Work? Yes, it is work. So either you run the metal detector, or you let the metal detector run you...

I like running myself so I dig...
Melbeta

[kt315]

I WOULD LIKE TO ASK IF THE PCB FROM KING COBRA ARE IN STOCK ?? IF YES COST FOR 2 PIECES ??

whole batch was been sold. i am at end of refreshing of the layout now.
late i will order new pack.
pleasure

[RelicHunter1388]

Yes, both switches are 3 positions of. This is seems from the photos I did put.
NOTCH - ACCEPT/OFF/ REJECT
MODE - DISC/ALL METALL/SET ALL METALL.This right position is NOT fixed, not fixedable, is only clickable. Althought you can take and use ordinary 3-P switch, but you have to remember to set the switch in middle position anytime (or fixed left one). SET - I mean you set the S.A.T. circuit to some zero, althought there is nothing new - you have to see this part in TGSL too and may be reading about.

Is the MODE switch an ON-ON-MOM type?

I have the PCB for ten years and now that I got the time I decided to finally build it. So far I found ON-OFF-MOM switches (MTS-213 DPDT 6-Pin and MTS-113 SPDT 3-Pin) that are apparently very rare, and some even more rare, and also very expensive, used ON-ON-MOM switches from the States (that will cost as much as a used metal detector to ship here).

But, if in the Parts List the NOTCH is a "3 Position" and that translates to ON-OFF-ON, then the MODE, which is a "3 Position with momentary" should be a ON-OFF-MOM, right?

However, in a previous post it is stated that a CMOS opamp for IC8 must be used in order to be able to use the ON-OFF-MOM SPDT switch. Is that integrated into the King Cobra PCB? Or it has to do with the switch type? Namely, ON-OFF-MOM DPDT is what should be used for the King Cobra, but a ON-OFF-MOM SPDT wan be used if a CMOS opamp for IC8 is also used?

(The MTS-213 DPDT 6-Pin is what seemingly what it is used in most builds, but I cannot make the markings from the pictures, therefore I cannot confirm.)

[kt315]

i bought KING COBRA at ebay, for back-re-design, so this text was in owner-seller listing.

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I have for auction my Gold Mountain King Cobra metal detector.
This has been a backup detector and has seen little use and is in excellent Fully working used condition.
This is a used metal detector and there are slight use age marks but as you can see from the
pictures its in way above average condition for its age. I am only the second owner of this from new.
I have taken photos of all angles so you can see the condition of all parts.
I bought it primarily as a backup machine, it has been very well cared for and all controls function
as they should. Please note the mode toggle switch is a 3 way toggle, left for discrim, centre for all metal
and right spring loaded reset. The notch toggle is just 2 way accept/reject.
No headphones come with the detector. The headphone socket fits standard 1/4 inch
headphone plugs. Battery is NiMh and gives over 20hrs continuous use. Charger provided.
The battery is accessed via a panel at the front with two button clips.
A VLF slow motion discrimination detector using an 8" concentric coil, the detector operates at 15khz. Weight 3lbs
Auto ground balance, All metal and pinpoint non motion with adjustable notch discrimination if required.
This detector when first released was top of the range and is quite sought after due to its simplicity and
excellent iron discrimination.
Over the years i have owned most makes and type of detector and liken this to the laser/tesoro machines
in both ease of use and excellent detection of small silver coins and gold, roman coins etc.
I have enclosed a copy of the original instructions.
I will post by parcel courier to any uk address, sorry i am not shipping overseas.

******I will pay for postage******

******UK ONLY POST****** NO RETURNS

Any questions about the detector please contact me by ebay message.

Payment by paypal please.

This auction is fixed price buy it now, no offers please.