XP deus coil modification

[Skippy]

Q:"I can't see ANY different in performance.....the Deus isn't very difficult or sensitive to a good Null"
That's the point. The level of null makes absolutely no difference to performance until it is too high, then the machine will be awful / not work at all

One thing: That switch you have on you new box, is it in series with the Li cell? I'm thinking it may not be a good idea if you accidentally try charging up the coil with the Li cell disconnected. I doubt it will do any harm, to be honest: 5 Volt less a Schottky diode drop of 0.2V isn't seriously over-volts. One possible idea may be to fit a double-pole switch, and use the second pole to disconnect the + (or -) charging socket wire.

[Henrikras]

I'll will Be carefull Skippy.. The switch is only used when I'm soldering at the board. (Safety / turn off).

[golfnut]

I guess 24 bit is overkill, most micros dont have more than 14bit adcs. Most of the performance of these machines is in the quality of the dsp filters 0 these would have a great roll off and a short latency/lag so recover/settle quickly.

I know you can sweep these very fast for almost no degradation - the filters may be adaptive and the upper roll off and lower cutoff may slide about with user sweep rate.
Soggy / Laggy RC filters are a thing of posterity in here I feel.


Clever bit of kit - the benchmark in europe - even the older guys are coming around to these, as they are sick of watching others rape it while they go home with nothing.

[Skippy]

The odd thing with ADC's is that there are plenty of 16-bit ones, but then a huge gap until you get to 24-bit. Inbetween-sized ones tend to be specialist types, too, like fast, or very slow. So it's possible that in reality, only 20 bits are used, or maybe oversampling and averaging is used, to give a smoother 20-bits.
But if you're wanting to use a medium-size ADC, like 12 or 14 bits, in an MD, you would probably use some kind of compression in the pre-ADC stages, I think.

[Henrikras]

Hi.... Any comments are Welcome.
First try to make this small Deus coil will be from a CTX 6" cover. (See picture).
The finish searchcoil will be like a 5-5.5" coil. (See the plastic tube is in the centre of the cover).

1 turn inside the tube tight, gave 32,5 cm. / Thats a inner radius 51.7 mm / then I say 52.0 mm.
I need to get close to the Stock coil = RX 15.9 mH and 70.0 ohm and TX 10.4 mH and 20.4 ohm.

RX: With 0.16 mm wire 15.95 mH = 246 turns x 33 cm (the inner + 0.5) = 81.2 meter x 0.856 ohm/m = 69.5 ohm.
and + 2% is 251 turns x 33 cm (inner + 0.5) = 82.8 meter x 0.856 ohm/m = 70.9 ohm.
I will properly go up to 255 turns to Be sure that I will get more that 15.9 mH.

TX: With 0.28 mm wire 10.4 mH = 210 turns x 33 cm = 69.3 meter x 0.268 ohm/m = 18.6 ohm
And +2% is 214 turns x 33 cm = 70.6 meter x 0.268 ohm/m = 18.9 ohm.
I will properly go up to 217 turns to be sure that I will get more that 10.4 mH.

I will try to make a special windings process by holding the two plastic tubes in same level, so I can wind the wires like first 10 turns RX the 9 turns TX, the 10 more RX and so on to the end (like weaving the wires together)... It could Be difficult, but I'll will try.
The Winding Channel at the tube must Be made like a S, to get the wires inside.
Maybee this process will make the nulling impossible !! To that I will use some vaseline at the place the wires are crossing, so its posible to move the RX from the TX a little with out to much force...
I think this could make a Very good searchcoil If its succesed. (They call me Crazy Henrik, now you know why.)
Ive ordred this Compound to finish the search coil : http://www.circuitspecialists.eu/bla...ating-compound
Donald (DB Shells) Helped me with good adwises.
Henrik.

[Skippy]

I don't understand this 'weaving' process. Surely you need the windings to be seperate, so you can capacitively shield the RX from the TX, with it's own complete (graphite paint etc) shield. And maybe the same for the TX, I don't know how important this is, it just seems like a good idea..

I notice that your DD coil cover is marked 'PP'. This is polypropylene, a very slippery plastic, related to PTFE. Very few things stick to it, and specialist adhesives are few, and often very expensive, requiring special surface preparation.

There's an error in your mathematics, concerning resistance:
"210 turns x 33 cm (the inner + 0.5) = "
Your TX wire bundle is about 4mm diameter, so the mean radius is 2mm more than the inner radius, and so the mean circumference is 2 x pi x 2mm more than the minimum circumference, which is 12.5mm. Not 5mm, ie. (325mm + 12.5mm) = 337.5mm.
And the same for the RX, roughly, though the bundle size is smaller, more like 3mm.

[Henrikras]

Thanks Skippy... You saved my day.

[Henrikras]

Some delay... The first four experiments to wind is gone wrong - 0.16 wire broke two times, then my plastic tubes couldn't like the kontact 70 spray, ist broke in many pieces.
Now I would try a new idea. Parts are ordred.
Henrik.

[Henrikras]

Got some exsperience to day - Coil winding failed again. Tryed to wind the TX to a 5x8 eliptical. Goal was 20 ohm and 10.4 mH.
The Inner diamater is 71.5 mm. ( One turn the first to wind was 45 cm ). Then I sayed inner d 70 mm just to Be sure.
The last winds was 47 cm, so it should Be close to okay - (45 cm at the start and 47 cm i the end)
Was using 0.28 wire (0.268 ohm / meter ). The Calculator said 173 turns = 10.4 mH = 18 ohm. To be on the safe side I did 185 turns.
The 185 turns ended with 23.3 ohm... BUT only 9.4 mH... What is happening ???
23.3 ohm with 0.28 wire (0.268 ohm/m) is 87 meters... With a turn at 46 cm (45/47cm) ist close to my 185 turns....
It seem to me that with this Very long small type eliptical coil, I must add 12-15% to get my Inductance ???
I have to go one AWG size up to 0.315 mm, at the next try... And add 15-18% to Be on the safe side. (Easyer to take some turns off)
Can I had done something wrong ? The meter still say 10.4mh at the Stock coil.
Henrik

[Skippy]

Ok. First: I agree with your calculations in terms of the equivalent circular coil. HOWEVER: you keep on changing the bloody shape of your coil all the time. And that means the few percent correction factor keeps changing, but you never tell us what you're winding!!. This thing in your picture is VERY elliptic, you've never mentioned wanting to make such a non-circular coil before - I just measured it as 2.6:1 ratio. That's way beyond any of your previous attempts, even more elliptic than the Teknetics T2 shape (about 2.4:1). You likely do need to calculate for +6% inductance to allow for the shape.
Secondly, your wire bundle is not bound up tightly. Each strand of wire couples with it's neighbours. If they are spread out, this effect reduces, and the result is less L. How much less? I don't know, 2% possibly, may be 5%, I've never measured it, and I don't know how loose your coil is.
Plus, there's always the possible inaccuracy of your L-meter.
This plastic tube idea makes getting a tightly-bound wire bundle difficult. Just make a wooden board with dowel pegs as a winding jig, then bind up the wire bundle with cotton thread. I will email you some pictures.
And finally: Why are you making an 8 inch long coil?

[golfnut]

I agree with skippy, the coil winding in a tube is difficult - and makes it really tough.

most coils dont go with wire thinner than 0.2mm - 0.1xx often breaks.

steve

[Henrikras]

Thanks Skippy and Golfnut.
Its a learning fase to me and your advice and help ist great. But I don't think ist so bad to try out different of sharpes, to get some exsperience and if I succesed to wind one coil in good quality, and it ends so good that I can connect it to the Deus, to see whats happens, it would give us some data to work with.
Yeah it would cost some wires and time, but Thats all.
The 6" coil is Very difficult to make because the CTX Shell is Very soft and the sides are Very low at the shell. I haven't given up the 6" but the 0.16 broke so many times, and with the Very low sides... I'll wait a little with that.
Soon I will get some 7" Shells and a 8" closed one, from DB. That would Be great.
Playing with the 5x8" was just to get time going and getting some exsperience.
The picture is the Shells from DB coming soon.
Ps. This 9.4 mH I got latest, must Be a combination of lose wires and very small sharpe. Nevermind learned some new stuf.
Nice sunday to you all.
Henrik

[greylourie]

Hi Henrikras,

If you really want your coil bundles inside the tubing.... then why don't you : (1st) wind coils on wooden former, using pegs to determine coil shape/diameter, and then (2nd) bind bundle with thin thread/twine, and then (last) cut tube longitudinally and fit it over the coil ?

I have been following your thread, and think it is a very interesting one. But I cant remember if you described why you want your coils inside tubing... is it so as to make attachment and adjustment inside housing easier ?

Anyway, maybe my suggestion to wind coil first, then put inside tubing - might give you some ideas. And save you broken wire..

regards grey.

[Henrikras]

Thanks Grey.
two reason why this tubes idea.. 1. I hoped the wires would find its nice place Winding, because the tube is round inside. 2. If the finish coil ever should get shielding, I hoped it was easyer to do at the outer side of the tube, allso because that would give a distance from the wires to the shielding (the plastic thickness).
All my earlyer try with wooden pins did not make a nice looking coil. (Picture from a project with a 13" coil)
Good idea to cut the tube logitudedially. Thanks
Henrik.

[sinclairuser]

All my earlyer try with wooden pins did not make a nice looking coil.
Henrik.

if i have learned one thing winding coils its that since its in a case and resin sealed how it looks means nothing, all that matters is the correct specs as once its sealed in one of dons shells it will look fantastic anyway.
dont get hung up on how the bundle looks, have you seen the state of some commercial coils if you open them up?, yet they work fantastically.
ally
p.s. not trying to be rude, but you seem to be making a hard task impossible imho.