IDX-PRO+VDI

[Silver Dollar]

Part of the trick to using Graphite is to burnish (or rub) the surface after it dries. This spreads the
molecules and makes them contact for a continuous connection...

[golfnut]

graphite - I do square test cards, I struggled to get repeatability. I get patches or zones of good low res. Then areas that are high.

Can be tricky, commercial coil vendors all do their graphite or carbon a bit differently and guard it.

You want a few k ohms per square

The ratio of paint, epoxy, carrier to graphite I got best results with was 50/50 by mass, my better ones were with really thin epoxy- as thin allows the graphite to touch together, all were a bit average, I don't have a killer recipe...

Satdave got results with cheap yacht varnish and graphite.

Sand paper the shell to key it.

Carbon paint for remote control traces would be good - this is a high temp industrial process and no use for us. There is a low temp carbon but sourcing as a amateur is tedious.

Graphene is something that should be great - but too new and pricey

The best function for time outlay is cheap survival blanket, it must have exposed metallisation on one surface so fine drain wire connects - some from value shops are often best. Premium ones from adventure stores have plastic both sides with the metal inside - you cant connect to these.

[hoadlies]

Valters... Going for tight tolerance expensive caps will not help you .

Barry, the molybdenum is not used for a couple of reasons - 1) Its magnetic! Not what you want 2) a great friction modifier - the coil and potting may drop out

S

YES G/NUT,, I tried some on some paper & found also that it is not conductive either ,, I need to mix some Graphite powder as I do have some i will experiment with that ..

HAVE a Good-Day..MATE,,,,,,,,,,BARRY..

[hoadlies]

Hey Barry.
When I built my IDX coils I copied what I could measure from my 6" Blue Max coil. The phasing on my home builts came out good..meaning the GB and DISC pots were somewhat mid-range. The phasing is most critical as you will not be able to GB is this is off. Even 1/2 a turn off with the Tx coil can screw things up. The IDX coils are less tolerant than the TGSL coils when it comes to this. You may want to wait until you complete your PCB before you cast your coils in glue as you may need to make a few minor tweeks but this should land you in the ballbark.
Don

HI DON THANKS for you valued input YES I really need to wait untill I get my Kit & get it running prior to fixing the Coils ..
Wire Diam & No of turn to achieve the correct balance seem's most important ..


I will after this DD coil build have a go at your Coplaner Coil you described ,But I need to Stock-up on some Wire & build some winding formers to suit & obtain some of the Graphite spray you use ..
I will persevere,,Mate..

I thankyou for the Input ,,,,,,,,,,CHEERS BARRY..

[hoadlies]

Thicker TX wire changes the "Q" in a good way. The lesser resistance helps with creating a stronger field.

On RX the thinner wire is actually better as the increased resistance matches impedance better for
less noise. Of course these are just guidelines for making the best you can. I used 0.25 mm wire for
both coils on my TGSL (but found out the wire was more like 0.22 mm) but since reading about
IGSL have made a 0.55 mm TX coil and a real 0.25 mm RX with lots more windings.

The trick is that no matter what you do some coils come out better than others so build one and glue
it but be prepared to throw it away if it doesn't work well. I think Ivonic tossed 1 out of 4. The difference
between a good one and bad one is depth and or noise.

On shielding I am currently making center tapped coils with no shield for best performance. My second choice
would be some sort of screening (like you use on the windows to keep bugs out). I found some that you can
solder to (a loose shield or broken ground to the shield will make your coil unusable). Aluminium foil works but
thinner is better. I tried some Mylar balloon type foil but it rips easy and is hard to work with. Graphite is a good
choice, I'm not sure about moly, although it is a metal I've never heard of how well it conducts...

HI ,,S/D ,, THANKS for the Input it is good info from you ,,that have built many coils ,,I will no dought have to build a few coils to get it Right ,But learn along the way ..

Interesting Fly-Screen YES you can get Brass Flyscreen I think & can solder that Ok ..
IT seems the GRAPHITE Spray is the Simplest method seen here on the site & or to mix powdered Graphite with a glue -Varnish etc ..

I tried the MOLY-COTE spray & its ''NOT'' conductive so thats squashed that rout..

INTERESTING the Centre-tapped Coils ,Would they be difficult to build as to obtaining the centre tap ??? ,Or do you wind 2x coils so as to adjust each to balance????
I guess if you were positive of No of turns & tapped at the Middle of winding as you wound it ????

IT seems that we need A good supply of various guages of wire [NOT CHEAP] here in OZ at least .
I read somewhere that Old TV tubes had some usable wire behind them & I have just thown out several older models As Digital has now taken over here in OZ ,I also thew-out many old style Comp,
Monitors [BUGGA] Need to scrounge some-up HA.Haar..


I can buy rolls of 0.2 @ $22.00 AUD But it will only do one RX coil ??,, I am still looking for a better place to buy larger rolls cheaper ..


THE TX Coil I wound was Wire from a 12v oil-filled coil [CAR-IGN] primary easy to reclaim & was 0.7 , THERES Just enough for the 35 turns with some over ...& using YOUR explained method of the SIG-GEN & SCOPE worked out great ''THANKS''..

I much appreciate all the Help I have been given BY you S/D, G/nut,DON & others I hope I can complete this IDX to Show I have not Wasted your Time ..

WELL we got a change here today & I can get off my ''Backside '' & get out to my W/Shop as its been too hot during the day to work in there 44c ..

CHEERS TO ALL,,,,,,,,,BARRY..

[golfnut]

Valters... Going for tight tolerance expensive caps will not help you .

Barry, the molybdenum is not used for a couple of reasons - 1) Its magnetic! Not what you want 2) a great friction modifier - the coil and potting may drop out

S

[dfbowers]

HI DON thanks for the Reply ,, YES its B*****y hot here mate 44c for 4 day in a row ,I will send some of over to you HA.Haaar..

OK I am doing a DD coil [1st attempt] I used 0.7 wire for TX it ended up OK as to resistance reading & mH come out ok [Did the test as Silver-Dollar described with the S/GEN & my old single scope & 1 uf cap seems around the camp 6.5-6.6 Khz..
But for RX coil still unfinished I wound 290 Turns of 0.24mm wire as I had it here to use for TGSL now not doing that so used it for IDX DD.., I am yet to tighten up coil for a test mH reading !!]
But as it is Its close to the readings You describe for RX ..I will report back after More work on it ..

Can I do a similar test for RX as I did with the TX using the Signal Gen & scope & cap trials ,If so what frequency am I looking to obtain?????DID I read 4900hz ?????ie 4.9 khz????

SHOULD be a cool change coming tonight ?? this will allow me to get out to my W/shop where I am working on these coils ..Still awaiting my KIT for IDX ,Very keen to get started on my 1st build ..I have printed all I can find on the various build mods etc posted here BY EDUARDO ..

I am to use aluminium foil [Self stick on a roll] I cannot find Graphite dry-lube as yet But my son gave me a can of MOLY-cote spray Dry-Lube """MOLYDNIUM ????? I will test that on paper to check conductance ???Any one used that ????

THANKS for the Help Much appreciated ''VINTAGE-BARRY'' @74..

Hey Barry.
When I built my IDX coils I copied what I could measure from my 6" Blue Max coil. The phasing on my home builts came out good..meaning the GB and DISC pots were somewhat mid-range. The phasing is most critical as you will not be able to GB is this is off. Even 1/2 a turn off with the Tx coil can screw things up. The IDX coils are less tolerant than the TGSL coils when it comes to this. You may want to wait until you complete your PCB before you cast your coils in glue as you may need to make a few minor tweeks but this should land you in the ballbark.
Don

[Valters]

Now one beginner question.
In my first IDX I use MKT +/-10% type capacitors, now I will try second one.
Is sense to use FKP +/-2,5% (3x time expensive that 5% and 10x than 10%) type capacitors or it is enougt with +/-5% MPF type capacitors or even 10% MKT?

Your opinion?

[Silver Dollar]

Thicker TX wire changes the "Q" in a good way. The lesser resistance helps with creating a stronger field.

On RX the thinner wire is actually better as the increased resistance matches impedance better for
less noise. Of course these are just guidelines for making the best you can. I used 0.25 mm wire for
both coils on my TGSL (but found out the wire was more like 0.22 mm) but since reading about
IGSL have made a 0.55 mm TX coil and a real 0.25 mm RX with lots more windings.

The trick is that no matter what you do some coils come out better than others so build one and glue
it but be prepared to throw it away if it doesn't work well. I think Ivonic tossed 1 out of 4. The difference
between a good one and bad one is depth and or noise.

On shielding I am currently making center tapped coils with no shield for best performance. My second choice
would be some sort of screening (like you use on the windows to keep bugs out). I found some that you can
solder to (a loose shield or broken ground to the shield will make your coil unusable). Aluminium foil works but
thinner is better. I tried some Mylar balloon type foil but it rips easy and is hard to work with. Graphite is a good
choice, I'm not sure about moly, although it is a metal I've never heard of how well it conducts...

[hoadlies]

Hi Barry. I found that the Tx wire size mattered more than Rx.. if Tx is too small you do not get full tx amplitude. If too large it becomes difficult to work with. I built two concentrics for the Idx with different wire sizes for the rx and could not tell any difference except the value of R was a little off. Hope you are staying cool down there in aussie land! Its plenty cold up here!
Don..

HI DON thanks for the Reply ,, YES its B*****y hot here mate 44c for 4 day in a row ,I will send some of over to you HA.Haaar..

OK I am doing a DD coil [1st attempt] I used 0.7 wire for TX it ended up OK as to resistance reading & mH come out ok [Did the test as Silver-Dollar described with the S/GEN & my old single scope & 1 uf cap seems around the camp 6.5-6.6 Khz..
But for RX coil still unfinished I wound 290 Turns of 0.24mm wire as I had it here to use for TGSL now not doing that so used it for IDX DD.., I am yet to tighten up coil for a test mH reading !!]
But as it is Its close to the readings You describe for RX ..I will report back after More work on it ..

Can I do a similar test for RX as I did with the TX using the Signal Gen & scope & cap trials ,If so what frequency am I looking to obtain?????DID I read 4900hz ?????ie 4.9 khz????

SHOULD be a cool change coming tonight ?? this will allow me to get out to my W/shop where I am working on these coils ..Still awaiting my KIT for IDX ,Very keen to get started on my 1st build ..I have printed all I can find on the various build mods etc posted here BY EDUARDO ..

I am to use aluminium foil [Self stick on a roll] I cannot find Graphite dry-lube as yet But my son gave me a can of MOLY-cote spray Dry-Lube """MOLYDNIUM ????? I will test that on paper to check conductance ???Any one used that ????

THANKS for the Help Much appreciated ''VINTAGE-BARRY'' @74..

[hoadlies]

THANKyou THOMAS for that information ..

Nice calculator ..

CHEERS BARRY..

[dfbowers]

Hi Barry. I found that the Tx wire size mattered more than Rx.. if Tx is too small you do not get full tx amplitude. If too large it becomes difficult to work with. I built two concentrics for the Idx with different wire sizes for the rx and could not tell any difference except the value of R was a little off. Hope you are staying cool down there in aussie land! Its plenty cold up here!
Don..

[Thomas]

What you saw was the copper area, should be .16mm

[hoadlies]

My project of the week..

http://www.youtube.com/watch?v=buU4h2QpgOw

I wanted to see how cheap I could build an 8" coplaner coil for IDX. Turns out, under $20.00! I did have to break out the vacuum forming machine. This was not an easy project compared to a DD coil as tuning was a little tricky between the Tx coil and the bucking coil.

Start with a sheet of 1/2 inch foam board from a craft store - It's "large cell" foam, that is somewhat brittle but also stiff.
It is cut into a donut shape to accept a spool for the Rx coil.
The Rx coil is wound on a homemade spool of cardboard with a foam center.
The foam "donut" is then glued to a sheet of stiff cardboard and the Rx spool is glued into the center.

The Tx coil is made on a separate former and held together with Cyan glue. Then this coil is simply glued into a channel cut into the foam. The bucking coil is wound opposite the direction of the Tx coil - directly on top of the Rx coil.
After tuning and nulling, the inner ring is filled with slow cure epoxy.

Rx coil - 3.25" - "about" 425t for 34 AWG wire (35 mH) wound counter clockwise + 33nF cap
Tx coil - 7.5" - 34t for 22 AWG wire (583uH) wound counter clockwise + 1 uF cap
Bucking coil - about 11 turns wound on top of Rx coil wound clockwise

For the best null, the hot end of the Tx coil must be connected to "Tx start" (P8 pin 1)
The grounded end of the Rx coil must be the wire closest to the bucking coil - " Rx end" (P8 pins 3 & 4).

For the tricky part - When the bucking coil is wound around the Rx coil opposite direction from the Tx coil, the frequency goes up by about 60Hz, so a turn or 2 will have to be added to the Tx coil to bring the frequency back down to 6.59kHz.After tuning and nulling, the inner ring is filled with slow cure epoxy.

For shielding, I used heavy gauge paper, covered with graphite powder from the hardware store. I just dumped some on the paper and rubbed it in until I got a conductive sheet of paper. The paper ended up with about 35k Ohms of resistance across the entire sheet yet is not detectable by the coil. A drain wire is then attached with masking tape and a bit of conductive glue made from a slurry of rubber contact cement and epoxy. Amazingly enough, rubber contact cement can become conductive if enough graphite is mixed with it. (maybe someone can comment on the effectiveness of this practice, but I can demonstrate that it does work).

For a cable, I just used Belden 8723.
Enjoy!
Don

HI DON ,, I find your Coil Building Posts very informitive ,As I am New to this hobby, Thankyou for your Sharing of your Builds ..

I find the AWG,SWG wire size guages very confusing ,But I found a conversion Chart thats helped ,,
WOW- 0.020 mm wire is very thin ,Do you find it hard to work with????,Also in AUstralia its not easy to find those Guages of wire in small rolls ..
QUESTION ,, how critical is the wire Guage ,in your opinion ???? Is it more important to get resistance value & or mH values ..
IS it possible to use thicker wire in the RX windings Be-it DD & or Coplaner ???? such as 0.24 mm..

I have a lot to learn here as I have Just gotten into this hobby..



CHEERS ,,BARRY..

[Valters]

Now one beginner question.
In my first IDX I use MKT +/-10% type capacitors, now I will try second one.
Is sense to use FKP +/-2,5% (3x time expensive that 5% and 10x than 10%) type capacitors or it is enougt with +/-5% MPF type capacitors or even 10% MKT?