XP deus coil modification

[ivconic]

It's certainly possible for XP to make a small coil - talk of not being able to fit the electronics/battery inside is not really true. You only need 18 &12KHz with a small coil, and users generally report that there is hardly any difference between the two, anyway. So you could just have one frequency. 12, 15,18 no real difference, then you can do away with the relays. The circuitry could be shrunk considerably, the LiPo cell could be half the size, probably smaller, as capacity improvements have been made, and you likely don't need the 'high power' setting anyway, as small coils pick up less EMI etc. If I was the designer, I would go for 2 freqs in a 2:1 ratio, like 8KHz & 16KHz. You can get smaller relays, those [durned expensive] TO-5 can type, I'm pretty sure I've seen latching types.
It's interesting that the TX winding in Hen's coil is just a plain single winding. When you consider it's likely to be driven from 3 Volts, you would think that a centre-tapped coil would be a good choice. They do that in the Tek T2, which has 5 Volt [+ maybe 6 V] internal supplies.

Even single frequency will do just fine.
I would not insist on smaller battery.
Present electronics can be packed in smaller coil with no problems.
Battery can be mounted on top of the coil, out of the coil enclosure in proper holder.
Even now i am considering simple and easy modifications for my present coils, when time comes to replace existing batteries.
I am planing to use standard 18650 high capacity (4200mAh is largest i founded) and mount it in water resistant holder, which i will somehow fix on the top of coil enclosure.
So each time i want to charge it; i will easily take it out from holder and put in a charger.
So far experiences tells me that such holder doesn't need to be strictly perfect water resistant, because my usual habits are not to go searching on rainy weather and in high moisture anyway.
Most of the time my coils are returning home perfectly dry. So there would be no danger for moisture to get in battery case.
So, guys in XP can plan similar setup for such smaller coils too.
Smaller coil may turn ugly in that case; but who cares as long as it does the job!
I remember much uglier coils from the past!

[Skippy]

I agree, Ivconic, one freq. is fine, but this is a Deus, and I bet Alain wouldn't want to sell a coil that makes the machine like a GMP, especially as it wouldn't be cheap.
Here's one thing not considered - how to obtain a good coil null. Some nulling methods only work at the single frequency they are designed for. Hen probably only wants 12 or 18 K to work well on his coil, which may help, but it would be good if the null was reasonably broadband. One way this can be achieved is by using a 'dummy target' of very high 'frequency' (L/R), I think this would require quite a lot of experimentation to get right, unfortunately, so maybe it's best to just aim for good operation at one frequency for now. You could always have a try at another coil later, as the electronics/battery are now seperate.

[Funfinder]

interesting topic.
at least now we know the coil uses a 5000mA/h lipo accu, pretty strong. Though I still would add a second one in parallel.

I would crack this babe by trial and error but with a still possible "get back to a working state"-option if the hacking does not work:

This means: do not destroy anything you can't fix again back to formerly state if the mod does not work!
Easier said than done, depending how good is the wire "melted" and glued into the coils-housing.

Henrikras, if you still should have this option, you're lucky, otherwise better order a new coil.
And don't start to mess with the IC-controller, it only converts the signal for the transmitter.

The most simple solution is to form an 8 out of the single D coils of the DD so the result are 2 double thick but just around half the size coils.
Leave the connections originally. Use the orginal pulled out coil-cables for it and bind it very tight together by scotch- or other strong fixing-tape,
until you achieve most possible sensitivity.


If it does not work, either remove some windings on each side, or add some extra capacitors, on both sides the same value.


But why the heck you wanna make the coil even smaller as it is already? Do you wanna find small gold corns?
If the Deus XPs "standard" coil is still too unsensitive for small stuff better forget this project completly!

For real effective and especially for real deep treasure-hunting the XP-standard coil is already too small anyway.

If so better get a special detector for extremly small stuff, or try some cheap Garrett Ace with 4 inch sniper coil.
You even can use one of those new high sensitive P.I.-pinpointers (ca. 2 inch coils) and modify it for ground-scanning.


Lets hope your experiments can help that in the near future we'll get some smartphone android MD apps.


Good luck.

[ivconic]

I agree, Ivconic, one freq. is fine, but this is a Deus, and I bet Alain wouldn't want to sell a coil that makes the machine like a GMP, especially as it wouldn't be cheap.
Here's one thing not considered - how to obtain a good coil null. Some nulling methods only work at the single frequency they are designed for. Hen probably only wants 12 or 18 K to work well on his coil, which may help, but it would be good if the null was reasonably broadband. One way this can be achieved is by using a 'dummy target' of very high 'frequency' (L/R), I think this would require quite a lot of experimentation to get right, unfortunately, so maybe it's best to just aim for good operation at one frequency for now. You could always have a try at another coil later, as the electronics/battery are now seperate.

Not necessarily. Smaller coil will not make Deus cheaper, by no means.
Not everyone of us wants to be prospector.
On contrary; most of the guys i know frequently asks for larger coils and greater depths!
I have my personal opinion and attitude about that... but this time i will avoid to be rude!
(It is always much cheaper to take a plane than to dig down your way to China!)
So, majority of customers will most probably insist on larger and "deeper" coils.
Besides, XP already made a lot of money; now is time to turn to "Socialism" and do something more for dedicated customers.
Small coil would be there only to cover prospecting area.
...
How to null such coil? Very interesting question. Before answering it; we must gain more infos.
We still don't know enough about Deus and idea which is behind it.
I agree, null at Deus coil certainly must be "broadband"... if any!
More i think on this; more i recall Davor's idea about unshielded coil setup.
What if we don't need no null and no shield at all?
What if we took whole signal that coming from coil and process it the way we want and need?
We don't need high TX power at all.
We will need series of digital filters which will pick only wanted segments from overall signal.

[ivconic]

Henrikras here is what i will do now, if i was you:
First, i would try to run only Tx coil from Deus on some of given frequencies. Rx coil i would leave unconnected.
I would try to scope (DSP scope obligatory) RX coil output directly on it's pins. Having on mind TX features i will try to measure residual voltage and signal on RX pins.
If Deus "feels" that there is no RX coil connected than it will probably refuse to give signal on TX outs.
If Deus don't "feel" that there is no RX coil connected; than i would be able to see what kind of signal it gives to TX coil. (freq. amplitude, vaweform...etc).
In first case, if Deus "feels" absence of RX coil; i would be pushed to attach RX coil too and again i will be able to see TX signal ( freq. amplitude, vaweform...etc).
Than, knowing all the TX signal features; i will make simple standalone TX oscillator to mimic the original one and it will serve me to make and null my custom coil.
(my post turned blue!?... it's a script, Carl!!!!!!)

[Skippy]

Quote:"Smaller coil will not make Deus cheaper, by no means"
that's what I said, it may even cost more, if it needs a redesigned, more miniaturised circuit-board - I imagine the Deus Large coil could use the same electronics board as the stock coil? Probably doesn't, though.
Quote:"Small coil would be there only to cover prospecting area"
Actually, we use small coils in the U.K on heavily iron-infested ground, often with Roman / Medieval trash. I think an official small Deus coil would sell over here - people use the 5 inch DD on the Tek T2 / Fisher F75 a lot for this reason. They have other uses too.

On the subject of power/batteries, one thing that I would try measuring is the DC current consumption, in all different power settings, and at all frequencies. The users manual gives run-time figures that vary considerably depending on settings, so getting good data on this might help choose power sources, etc.

[ivconic]

Quote:"Smaller coil will not make Deus cheaper, by no means"
that's what I said, it may even cost more, if it needs a redesigned, more miniaturised circuit-board - I imagine the Deus Large coil could use the same electronics board as the stock coil? Probably doesn't, though.
Quote:"Small coil would be there only to cover prospecting area"
Actually, we use small coils in the U.K on heavily iron-infested ground, often with Roman / Medieval trash. I think an official small Deus coil would sell over here - people use the 5 inch DD on the Tek T2 / Fisher F75 a lot for this reason. They have other uses too.

On the subject of power/batteries, one thing that I would try measuring is the DC current consumption, in all different power settings, and at all frequencies. The users manual gives run-time figures that vary considerably depending on settings, so getting good data on this might help choose power sources, etc.

Pretty correct points!
Can't disagree.

[Skippy]

One thought I've just had..is the circuit ground actually the LiPo cell negative, or is it a virtual ground? It wouldn't surprise me if the raw supply was regulated to 3.0 volts, and a virtual 1.5V was created to act as a 0 Volt ground. The RX coil, and screens if present, could connect to this (1.5V) point.. The Micro, ADC, 2.4GHz link, TX drive all would work from 3 V.

[Henrikras]

Sorry guys. Been at family birthsday and to morrow out detecting. But Thanks all your comments. I will read all monday.
Ps. The negative at the Lipo is not the same as the ground at the board.
Henrik.

[Henrikras]

Hello again.
I was out with my 11x13" at the test bed outside... Tape to hold the Battery and the board a little lose, but It just worked nicely..
Next thing to do; Coil production.
I am ready to ordre the AWG wire... Got AWG 30- 0.25 mm at Stock, but not AWG 29 or similar.
Can I ask you to look at my pictures... ! The coil cover picture is to show you the different between the 9" Stock coil, compaired with a smaller 5"x 8" DD coil.
I was wonder.. Is the difference between the two coils to small and then the advance or idea will end up to little ?
Still to Remember why this project is started. I got many places (coins and relic hunting), which is so Heavy iron infested that even in the fast Deus program or with higher reaction, ist very difficult.
Some of you would properly say smaller coil ! maybee like 4"x 6" - but dont you think the coil will end up to thick ?
I made a test... 4"x 6" and to make the RX at 14.9 mH = AWG 28 (0.32mm) I would need 235 turns and end up with 19ohm (Coil thickness 4.9mm)
I think it would Be a good idea to sleep and think this over a Night or two.
All comment is Very Welcome.
Henrik.

[Skippy]

You need to reduce the toe-to-heel length, so it looks at less ground and hence less targets at the same time. 5 x 4, or 6 x 4 is what's needed. As a follow-on project, once you have a perfect small coil made,[yes, we have high expectations] you may be able to increase the front-end amplifier gain, maybe by a factor of 2 or 3, to bring up the sensitivity.
A 5mm diameter wire bundle is not a problem, I think commercial small coils all have thicker windings, it's just inevitable, to keep L the same as the larger coils. You may be able to compromise slightly on the receive coil, and allow resistance to go up to 100R (ie. thinner wire) , though I would try and keep it lower than before, like 50R, as it is a noise source.
I would suggest building the coil up in a 6 inch circular housing, not a 'spider' type. This will hold a 5 x 4 butterfly coil arangement, with room for tuning bits and pieces, nulling loops wherever you want to put them etc.

[golfnut]

thats good advice from skippy - the ellipse will pick up targets IRON under its long footprint, a small round one will give a neat focused footprint - to reduce chance of mutiple pickup.

Some Thames mudlarkers use a 3" Steve

[Henrikras]

Thanks...
I will follow your ideas.
I found out that If its posible to find a coil cover with the right size, its more easy to build a search coil. You know to keep it stable in all the finetune process, that could Be a little hard to find so small .. 4x5 or 4x6..
I found a CTX 6" DD coil cover (see picture) with a lot of extra space (a 5.5 x 5" coil could properly the result with this, using the iner diameter, if the Winding isn't to thick.) That CTX 6" coil cover will Be ordered.
I was thinking... ! The finish coil will end up thick/high at the place where the RX and the TX are crossing. A Dream is to learn to
merge the RXs and TXs Winding.. Like start with one turn RX, then one turn TX.. I saw this at a Stock coil.
The turns 170 and 200 is Very similar, it just to count, and Once in a while turn 1:2 so both end in the same time.
Next is to ordre the AWG and a 6" CTX coilcover.
Henrik.

[Skippy]

How can you order the wire when you (we) have not designed the coil and worked out what size wire is needed? There's no rush to buy the wire, plus you've got to make a winding jig for it, too. Decide what physical shape you want your coils to be, then we'll go through the design process.

[Henrikras]

Your right Skippy.. I / we Need a little more thinking.
I had allso made a mistake yesterday... (One turn is not the same like one meter !!! )
Look at the new picture and you can see what I did wrong yesterday and you will allso see that we / I need Very thin AWG.

Henrik.