shielding concentric

[lamoiz]

black in the background .. it's graphite paint ... it covers the bottom and the edges ..

[lamoiz]

Good evening everyone
I poured the glue last night. araldite 2020 with micro balls.
the top shield is not in place yet, but I did another test on the grass.
the result is rather good .. there have been some false signals but very little compared to the first time.
tomorrow night I spend a layer of guitar cavity shielding paint on top and then re test it ...

[ripsdevala]

Hi lamoisz, what is your diameter of Tx and Rx, wire thickness, i just experiment with big concentric but fail

[lamoiz]

good evening Ripsdevala
the tx coil measures 30 cm and 0.585mh made of 0.75mm wires tuned with 1uf ... 26.75 turns.1.2 ohm
the coil rx measures 15 cm and 36.5 mh made up of 0.25mm wires tuned with 33nf ... 318 towers.56 ohm
the coil bx around rx about 6.2 turns with 0.75 mm.
the shielding is realized with graphite paint for guitar cavity. At the longest distance between the shielding of the cable and the coil the resistance is 2kohm but on average rather than 1 kohm.
its total mass with the epoxy resin is 520 grm ... much too much ...
here is all the info of this reel .. that works really well
bye

[lamoiz]

oupss for an IDX PRO silverdog .....

[dbanner]

Looking quite nice your search coil. Can you say what material used for spacing in coil?

[lamoiz]

Yes
it is a foam, attached to insulate the window 10 * 5mm .. glued with double sided

[lamoiz]

1 eur ... 28 cm ... after shielding above ....

[dbanner]

So it's working good now? noticed you shielded windings themselves.

[lamoiz]

yes working pretty well
The coils are protected from below, the sides, the top ..by graphite paint. the tests were void when I plunged the coils directly into the paint ...

[BKY1337]

I have a question. Today i sprayed my DD coils from my TGSL with graphite laquer.
Will a small cable over the gap destroy the effects of a faraday shield?

Like in this picture:

[dbanner]

Does the wire join the both ends of graphite, then yes, I believe so. It must not form a complete loop.

[BKY1337]

Thanks! I made it now without the wire over the gap.

[dbanner]

Also, wrapping a bare wire all the way around(except for gap) over the graphite reduces its overall resistance, This is like an extended drain wire. I see this done somewhere in video I posted. It appears that the resistance of sheild(graphite) is important. But it depends on the graphite mix you used, it may not be needed.

[BKY1337]

I have used Graphit 33 for the shield. I have 4 k Ohm with one coil. Everywhere at the coil.
But the other one has 100 k Ohm at on spot and 14 k Ohm where the wires go into the coil.

Do you think 100k is good enough?