IDX-PRO+VDI

[hoadlies]

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.

HI G/NUT-S/D ,,yes some interesting thoughts posted I am up for some Trials when I get to that part of the Farrady shield proccess..
But all of the Above posts are a great help..

G/NUT I was very taken by you comment Earlia in this thread [somewhere] that you actully mixed your Graphite with the Potting resin [killing 2 birds with one stone] so to speak ..
IS normal fibre-glass resin which is thin consistance& or can be thinned with Acetone any good to use ,as I see most seem to use the 2xpart epoxy tubes ..

I can obtain RESIN & I have done some minor Fibre-glass work ,making panels for my previous racing-cars..[speedway only]..

ON ANOTHER Topic ''WIRE'' I scrounged an old tube type TV & yes that shield ??? that wraps around the tube is a huge bundle of nice enameled wire but this one was 0.34mm approx diam..[BUGGA-just does not suit these coils , there miles of it that could easilly be rewound to spools ,.. I wonder if various brands use lighter guages ,,HAS any one tried to reclaim this wire???????..
As HERE As I have said its expensive to buy & the rolls are 100g only just enough for a RX or TX ..MAYBE I am being FRUGAL ,,HA,Haaar..

ON the wire subject Do those here that make DIY coils have a huge selection of Guages etc on hand or do some compromise on guages
[ie] use use alternate guages within reason to get the mH readings by experiment with wind-turns ?/?????

HERE in OZ I have found supplyers of wire to the Motor rewinding people but sell in very large quantities & not interested in the Hobbyist's ..

HAVE a good day Fella's,,,,,,,,,BARRY..

[Silver Dollar]

Carbon black like used in LaserJet or copier toner is good to use mixed into the epoxy. Make sure you use the slow set epoxy as
the 30 minute will not stand up to being wet. It's tough to find the slow setup stuff these days.

The OEM's most likely use stuff that we cannot buy or that we find too expensive. I worked at an underground radar company and
we used some special paper that had carbon inside with a layer of plastic on it. The printer burned threw the plastic to print. That
paper makes a good shield for the top and bottom of the coil but it costs $30 per roll!

[Tepco]

Check twice actual toner powder used, in different mixtures. I tried HP LJ6L toner (refilled) powder, it is completely non-conductive, in any mixture, useless for shielding.

[sinclairuser]

HI G/NUT-S/D ,,yes some interesting thoughts posted I am up for some Trials when I get to that part of the Farrady shield proccess..
But all of the Above posts are a great help..

G/NUT I was very taken by you comment Earlia in this thread [somewhere] that you actully mixed your Graphite with the Potting resin [killing 2 birds with one stone] so to speak ..
IS normal fibre-glass resin which is thin consistance& or can be thinned with Acetone any good to use ,as I see most seem to use the 2xpart epoxy tubes ..

I can obtain RESIN & I have done some minor Fibre-glass work ,making panels for my previous racing-cars..[speedway only]..

ON ANOTHER Topic ''WIRE'' I scrounged an old tube type TV & yes that shield ??? that wraps around the tube is a huge bundle of nice enameled wire but this one was 0.34mm approx diam..[BUGGA-just does not suit these coils , there miles of it that could easilly be rewound to spools ,.. I wonder if various brands use lighter guages ,,HAS any one tried to reclaim this wire???????..
As HERE As I have said its expensive to buy & the rolls are 100g only just enough for a RX or TX ..MAYBE I am being FRUGAL ,,HA,Haaar..

ON the wire subject Do those here that make DIY coils have a huge selection of Guages etc on hand or do some compromise on guages
[ie] use use alternate guages within reason to get the mH readings by experiment with wind-turns ?/?????

HERE in OZ I have found supplyers of wire to the Motor rewinding people but sell in very large quantities & not interested in the Hobbyist's ..

HAVE a good day Fella's,,,,,,,,,BARRY..

yes barry i've used wire recovered from crts, the bigger the screen the larger gauge wire used, in the loop from around a 32" crt telly, it got me loads of.50mm, i wound my coils with this and it was fine.
a mate recovered some 1mm enameled mag wire for me from the back of the tube, i did not fancy it as it looked a nightmare.
i think its best to leave the "loop" as it is trying to unwind it can result in a birds nest the .5mm i used had a sticky residue on it so i left it in the large loop and wound coils straight of it.
the 1mm i used to wind my pi mono loops it also worked well the ohms of the finished coil were closer to the specs than other wire i tried.

[golfnut]

Hi barry-- 0.34 would work too - use it fir the Tx coil and the 0.2mm for the Rx that would work well. Or 0.34 for both - There is no right and wrong - just practicality - 100/200/300 turns of 0.8mm wont go in the shell and will weigh lots. Plus cost a lot. Whereas 0.1mm would be not be great for Tx etc

0.2 - 0.4 is practical - having thicker wire in the Tx may give 10% more current/field but no tangible extra depth in use

Fit flexi entry gland to shell, prepare cable, Fit cable, secure gland compression / spot tack fine drain wires to shell and cable sheild and paint in carbon paint in shell and over drain wire but not to lip of shell - wait until thouroughly dried - carbon paint needs to be thin like a cellulose. but also needs to stick to shell ( waterbased acrilics fall off ) Roughen shell first. older grey car primer may be worth a go. oil based paints dont fi the bill as they never dry and make plastic brittle.

coils go in tack, null, phase.

pour in pot resin, which can epoxy glue, thin fast set or thick warmed /polyurathane car resin, /epoxy potting compound, /polyurathane potting coumpound mixed with carbon powder or very fine gapghite. or a blend.

medium gain size Graphite tends to coalesce into tarmac like paste which doesnt like to flow - I warm the carrier resin of choice in 50C oven to thin it - so it A flows, B sets quicker. need to try this so you dont get messed up. It sits flatter/ thinner with lower Resitance outcome.

Your shell should have enough depth to take your coils and some graphited/carboned resin to cover the coils - but have spare depth. ie conductive flood is not to the lip of the shell. Just below it. To the carbon paint finish depth line...

The idea is, the conductive flood does never touch the ground - you top off the fill to the brim with Black resin , epoxy or potting compound ( Robnor resins do some good ones on uk )

This top up final pot is non conductive, hard, and should have low water ingress. A commercial potting resin is best here, 80/90 shore hardness

During this process have coil conntected to your detector - scope the Tx sig and Rx preamp out. When you pour the first lot of resin, you may see a phase and null shift. Be ready to have to tweak this on the fly and prioritise the phase over null, while wet see you can still reject ferrite ,, Iron and accept gold bronze and silver. This way there will be suprises when set!!!!



This is the closest I know to commercial coil construction.

[hoadlies]

THANKS TO------ S/D,TEPCO,SINCLAIRUSER& GOLF/NUT ,, WELL thats anwered my Questions wonderfully !!!
S/D INK toner I would not have thought of that i have some Inkjet Black redundant from old printers I will give that a test [do a test on a small area ] ..That carbon paper sounds interesting as well !!,What about carbon paper used in ordinary note books ???? I will try the resistance to see if conductive ..

S/USER,,,, Great info on the reclaimed Wire I will try to get hold of more Monitors to check -out Guages As here in OZ all the old style TV/s are getting thrown-out as Digital has taken-over about 1 year ago ,people are leaning some on roadsides [Wrong but it happens]..
It would be nice to get some lighter Guages I will do more Scrounging HA.Haar..Maybe the older Computer monitors ?????..


G/nut A great explanation & guide-line's you gave,,& previously given,,,, I am to print out your suggestions as I have done for your mods given on the IDX for future use,,, After I get My kit running [should come soon] ..

THE amount of Information in this thread is A lot to take-in as I have read through it twice now & still miss something I try to print-out the important articles & put into a folder as My short-term memory is not good ''A-G-E'' SYNDROME,,, HA.HAaar..

I did some tests yesterday with the sig-GEN & scope & cAPS for the RX coil I wound using 0.24 mm wire approx 275-T.. [I originally had 295-T ,but removed some to get closer to mH ,when tied with dental-floss [Another great tip from you fella's] I settled with35mH &75 ohms resistance ,,This measured with multimeter with inductance capability [Maybe not as accurate as the digital units I see most use here] ,I have 2x Multimeters that Differ ,so I selected the one I feel is most accurate ?????I really need to test a known Choke etc to determine if it is close???,..

i started with a 33nf [0.033] But got the best result's with 32nf ,A 22n+10n,, it came out to 4.7-8 Khz as DON recomended 4.6khz to 4.9khz ..
I am slowly getting the Idea of all this From much help from you people ,with you heplfull sharing of Info [much appreciated]

I am glad I had kept my old Scope ,SIG-GEN,& frequency counter which I nearly got rid of a while ago .. My old scope is only S/Channel but it is in good-Nick as It was given me by a friend as a 70th birthday gift & i never got to really use it much ..But will be usefull now ..I do not fully understand the working of it But getting to know it better now!!!
The new digital models cost an ''Arm-&leg'' more than a good M/D ..

I hope to be able to show My efforts as I get further down the track to prove to you all thats helped me with this my first M/D build ..

CHEERS TO ALL From AUSTRALIA ,,,,,,,,,,,,BARRY..

[Thomas]

I've found Solenoids are a great source for wire, already on spools and old printers and copy machines are a starting place. If you want fine wire, relays and shaded pole electric motors are a good starting place.

[hoadlies]

I've found Solenoids are a great source for wire, already on spools and old printers and copy machines are a starting place. If you want fine wire, relays and shaded pole electric motors are a good starting place.

HI THOMAS THANKS-MATE yet another avenue to look for Wire for our hobby..

CHEERS BARRY..

[hoadlies]

HI S/D Thanks for the LINK to EBAY ,, I have ordered 2x rolls to check-out ,, I was unaware that we could use ''TINNED'' wire PLUS insulated as is described ..

http://www.ebay.com.au/itm/PCB-Solde...ht_2138wt_1001


TAKE-IT-EASY ,,,,,,,,,,BARRY..

[6666]

That wire wrap wire is a good buy, I bought some for same price but it was only one hundred mts

[golfnut]

"It's tough to find the slow setup stuff these days"

Golfsmith do a decent shafting epoxy that takes about 16Hrs at 25C Ive used that in a PI coil - It is very hard. But light brown color

[golfnut]

Coil contruction without graphite

Another popular type..

[hoadlies]

HI,,, G/NUT,& ALL ,,, Thanks for the survival -blanket pic ,, ..

I have been experimenting with various liquids to mix graphite powder with ,, i tried estapol varnish [clear ] didn't seem any-good , but PVA [wood glue seems OK ] I have only tested samples on paper ???..

I have scoured the Australian Internet for aerosols of Graphite Spray & it seems only available in the USA&UK ,,..
I have a couple huge Graphite-Carbon brushes from the big-Wind turbines & are Powdering them-up using emery paper !!!& will mix that wth some Powdered graphite powder But looking for a better medium to mix it with ,,I have some Nitro-cellulose clear [Used in furiture coatings-Named CATILAC] it mixes with all purpose Thinners I will give that a go !!!..
I have Aluminium Shielding Tape 1'' wide roll ,but read here that its too resistive ????,so trying to develop the graphite mix liquid ..

GOOD news ''MY KIT has arrived'' so the Shield is on the back-burner untill I assemble that ..
The board [IDX-PRO] is much smaller than I thought [Very -Very compact]..

I notice a few differing differences to some of the pics I D/loaded from here ,.. This Board has had the short remedied .. [Should I adhere to the Lay-out as printed on the Board ????]as I find theres differences in the Schematic I have & the Parts list ???

Well its getting there I order'd a 2 tone Board from S/DOG yesterday for later add-on..

I have your posted schem ,,Is that a final Copy ..

PICS of progress & my Messy music-room w/Desk ..

CHEERS BARRY..

[golfnut]

Hi Barry -

my advice would be build as per the silkscreen - the schematic is then not a priority.

I have requested a blank board from Andy to generate a schematic for your pcb version. Steve

[hoadlies]

Hi Barry -

my advice would be build as per the silkscreen - the schematic is then not a priority.

I have requested a blank board from Andy to generate a schematic for your pcb version. Steve

THANKS STEVE ,,???[G/NUT] OK MATE that I have done & I will set it up with the pots etc & do a ''Smoke-test'' HA.Haar..
Can do alterations [Mods after its up & running ..] IF need be..

I find your potting & Screening method posted earlia in this thread Excellent but I need to fashion-a Shell for the DD/Coil I made as they are not available in OZ , DON can sell me one Cheaply $9.00 USD. but the Postage from the US is $44.00 odd uS dollars making it too expensive ,, I see Coil wear plates I was wondering if I could utilize one of those at least for the bottom?????Otherwise I see some use flower pot Saucers.. I guess its up to the imagination to find something ..

WELL its cooled down now over the last 2 days & its comfortable to do this Project ..
HAVE a good day Mate ,,,,,,,,,,BARRY..