IDX-PRO+VDI

[seadoggy]

Not happy now. I get 100 ohms on one half of the shield and 500 on the other. Made two tap points to test the cut one off. Hope my shield is going to be okay ???

Need to sort some space out so I can set the null point I have metal everywhere in the house.

maybe wee dont make something good,i try put drain wires to have better resistance but same problem over ground so i quit from that metod.

See this mate
https://www.youtube.com/watch?v=SqM6eWwLIUs

[dfbowers]

I make CC but i cant make shield.in my country dont have that graphite spray.
I try use varnish and graphite powder but i dont have any success.The coil become alive over ground.i get about 300 to 400 ohms all around coil.
Is is possible use foil on CC??

Foil is too conductive.. but, pencil graphite works too! The first shield I made was made from paper covered with graphite from a simple pencil. Try it.. you will find that it is conductive.

[seadoggy]

Foil is too conductive.. but, pencil graphite works too! The first shield I made was made from paper covered with graphite from a simple pencil. Try it.. you will find that it is conductive.

with what you mix??or you just rub pencil on paper

[dfbowers]

with what you mix??or you just rub pencil on paper

Yes, you can apply graphite to paper by just rubbing it on. It will take you a while to cover a sheet of paper but it can be done. I'm not sure how much is optimum. You can check it with an OHM meter. You can connect a drain wire to it by making conductive glue. Mix a small pile of graphite to epoxy or rubber cement and it will become conductive as well.

[6666]

If all you have access to is pencils, try getting a carpenters pencil, carefully cut the wood off, this will give long lengths of graphite to rub on paper , adjust length to suit.
For temp testing a paper clip will work for earth wire.

[sinclairuser]

what i used were graphite pastels, they are the same stuff as inside pencils they are graded the same hb,2b etc.
i ground them in a pestle and mortar to a fine powder, i used this to make my graphite paint i tried carbon brushes but they are too hard, these pastels are easy to grind.
using these would be easier to put a certain amount on the paper.
i got mine from the range, but any art shop has them, and they are no more expensive than pencils.

[DOOLEY]

I looked at those,

if I remember right they were £15 in W.H.SMITHS,

I was a bit put of by the price,

esp as it would have been a gamble as to weather or not it would work.

I settled for aluminium for my boxes and coax tinfoil for my coils,
and that works just fine for me.



may try that method in future though.

[seadoggy]

what i used were graphite pastels, they are the same stuff as inside pencils they are graded the same hb,2b etc.
i ground them in a pestle and mortar to a fine powder, i used this to make my graphite paint i tried carbon brushes but they are too hard, these pastels are easy to grind.
using these would be easier to put a certain amount on the paper.[ATTACH]32443[/ATTACH][ATTACH]32444[/ATTACH][ATTACH]32445[/ATTACH]
i got mine from the range, but any art shop has them, and they are no more expensive than pencils.

With what you mix that powder mate??i try varnish for wood but dont have good results.
regards

[scrungy_doolittle]

With what you mix that powder mate??i try varnish for wood but dont have good results.
regards

You do know that Laser printer toners are for the most part carbon black and plastic. Many of them are magnetic too. Wonder how those would work?

[Koala]

I just bought the carbon powder from eBay not that expensive.

Mixed with yacht varnish gives good conductivity but not tried in the field yet


one table spoon of powder to one of varnish. Then added a bit more varnish till its runny. One batch came out at 100 ohms per square inch the other batch cam out at 500 ohms


someone tried toner and found it none conductive but all toner might not be the same. A carbon battery works well for testing but I suspect it will corrode the tap wire over time

[Qiaozhi]

You could try this ->
http://www.rapidonline.com/mechanica...-200ml-87-0695

[seadoggy]

I just bought the carbon powder from eBay not that expensive.

Mixed with yacht varnish gives good conductivity but not tried in the field yet


one table spoon of powder to one of varnish. Then added a bit more varnish till its runny. One batch came out at 100 ohms per square inch the other batch cam out at 500 ohms


someone tried toner and found it none conductive but all toner might not be the same. A carbon battery works well for testing but I suspect it will corrode the tap wire over time

nice mate now test at field and see what result you have,my is not good

[Koala]

I don't full understand the shield. I can make the coil that matches or exceeds a factory coil. I have yet to make a coil that runs as stable as a factory coil.

This coil I have place a 2mm thick piece of between the shield and the coils. Never taken a Whites coil to pieces but they are over an inch thick so there must be some packing around the coil


I have also made the shield quite a bit bigger than the coil so the leading edge of the shield should hit any change before the coil


Are well only time will tell.



Its easy to make a coil that will work over dry powdery sand. the coil will almost run without a shield. Take that same coil and run it over bumpy wet grass ground and ever clump sounds off.


Got off to a false start using a space blanket. Tried loads of different way in fact some were worse than not having a shield at all. As a guess I would say that the small areas of overlap act as a kind of capacitor.

[der_fisherman]

What glue to use with Graphite powder?

With what you mix that powder mate??i try varnish for wood but dont have good results.
regards

I have never done this myself, but if I was going to do it, I would pick a liquid fiberglass resin with a slow cure time to mix the graphite with, and not to mix too much up at a time. Several coats will usually be better. If using Polyester, put on the next coat just as the coat before is almost cured/hard, it sticks better then. Epoxy works hardened or not!!

Its available in quite large quantities, in plastic bottles from some online suppliers.

Denatured alcohol will also clean fingers and the like provided it hasn't fully hardened...Buy plenty!!

If using Polyester, which is usually cheaper, you need a slightly roughened surface for good adhesion....of course it also improves Epoxy resin bonding as well! Mix the Graphite into the binder well, before adding the correct amount of hardener, once you are happy with the consistency.

A warm environment will speed up hardening quite dramatically!

Always clean the surface to be glued with the alcohol and do not touch the surface with your fingers anymore before glueing as perspiration/sweat may preven bonding....

Of course, throwaway rubber gloves can also be used to great effect as well....

Epoxy resin "sticks" better to most surfaces but is usually far more expensive....not that I am fully upto date on prices!!

In some countries idenatured called methylated spirits by the way......

Regards

Andy

[mohandes]

hi all.
in all VLF detector which is have best disc and stability /
regards