IGSL

[Koala]

i try wood varnish i get about 450 ohm,
i also will try this metod

500 ohms and 1K works well in the real world. 100k ohms not so good. Wonder what the upper limit is for a good shield.


How well does the alcohol and graphite stick to the plastic ?

[seadoggy]

Thanks for ionfo
there are 3 types of wood varnish, water based, oil based, solvent based, while I have not tested it, I would avoid the water base, oil base works ok, I've been trying to get some solvent based varnish to try.

i try wood varnish i get about 450 ohm,
i also will try this metod

[6666]

Thanks for ionfo
there are 3 types of wood varnish, water based, oil based, solvent based, while I have not tested it, I would avoid the water base, oil base works ok, I've been trying to get some solvent based varnish to try.

[Koala]

Hi Koala what ratio of graphite powder to PVA glue did you settle on ? I found that you need a high amount of graphite like 1:1 to get a low resistance with PVA glue, I found useing wood varnish to be best for low resistance .

Yep 1:1 is about right.

First I add two small squares of copper foil. (copper slug tape from B & Q) Then solder a tag wire to each. Add a table spoon of graphite into a bowl. Then add enough PVA glue so its a stiff past. About the same as toothpaste and towel it on with the back of the spoon. You have to be quick it starts to go off in a few minuets. from memory between the two points came out at 500 ohms whereas two points on the surface was much higher. Once I know I works I cut off one of the tags. This was the quantity for a 6" coil

I found a disk of card above and below the coil more effective than applying directly to the windings. Did read somewhere it best to use graphite on a smooth surface. I don't use a coil shell so can't apply directly to the shell.

I also tried epoxy resin/graphite mix did not work at all. Rubber glue/graphite also failed. Graphite/yacht varnish worked but not as well. Also reacts with the epoxy resin I was using


Not tried normal wood varnish.

[6666]

Hi Koala what ratio of graphite powder to PVA glue did you settle on ? I found that you need a high amount of graphite like 1:1 to get a low resistance with PVA glue, I found useing wood varnish to be best for low resistance .

[Koala]

[QUOTE = DOOLEY, 212,032] Ben doğru hatırlıyorum
Eger. Uzun DON BOWER'S Bir Çözüm Sundu kullanılmaya başladığında. Ben ekli resimde çoğaltıldığını [ATTACH] 34802 [/ ATTACH] [/ QUOTE]



hi,this shield made alüminium of graphite,,Which is better than aluminum or graphite ?

I have had poor results with space blanket. Have a look on the IDX thread must have tried 10 different way with no success. The one time it half worked it did not last long. Not tried aluminium kitchen foil. After a bit of experimenting I have settled on PVA glue and graphite.

[Koala]

Very quick to try. None hot ends of coil to ground works fine.

[Koala]

if I remember correctly ,
a long while ago DON BOWER'S offered a solution.

I have replicated in the picture attached .

[ATTACH]34802[/ATTACH]

That's how I did it the second time works very stable.

[seadoggy]

if I remember correctly ,
a long while ago DON BOWER'S offered a solution.

I have replicated in the picture attached .

[ATTACH]34802[/ATTACH]

I dont quite understand that pic,if i connect rx- and tx - to same wire of shield i will get shortcut on PCB?

[kuzen]

[QUOTE = DOOLEY, 212,032] Ben doğru hatırlıyorum
Eger. Uzun DON BOWER'S Bir Çözüm Sundu kullanılmaya başladığında. Ben ekli resimde çoğaltıldığını [ATTACH] 34802 [/ ATTACH] [/ QUOTE]



hi,this shield made alüminium of graphite,,Which is better than aluminum or graphite ?

[DOOLEY]

if I remember correctly ,
a long while ago DON BOWER'S offered a solution.

I have replicated in the picture attached .

[seadoggy]

Ok mate_s i will try with 2 coax cable separate side by side!i have that cable here.
Also i tryed on my IDX USB 2.0 it not so good or i not connected shield well on pcb.
My IGSL working so good in air test get about 33 cmm gold ring .
Thanks you all on support i try cable and see what will happen

[ivconic]

That's the one I used on my original coil which worked fine except over wet grass. Must work as its the same as Tesoro use. The one that worked for me was to directly connect the four TX and RX to the four wires in the cable and shield to the shield of the cable at the coil end. Suspect its something to do with the epoxy and coil shell material and cable combination used. Original brown Tesoro coils are made out of a conductive plastic.

"Wet grass" issues are happening mostly when coil is not connected properly to cable or further to pcb, something must being reversed.
Looks like Rx or TX phase is reversed because of reversed pins or leads.
Both coils inside search head must maintain same winding orientation and plane. "Start" and "End" of windings must be somehow marked to avoid confusion.
Simplest check for this (without taking it outdoor on grass) is knocking on coil enclosure; if it is producing short responses: it is not wired properly.
If it remains silent on knocking; it is wired properly.

[Koala]

Here it is one of the options from the past;

[ATTACH]34801[/ATTACH]

That's the one I used on my original coil which worked fine except over wet grass. Must work as its the same as Tesoro use. The one that worked for me was to directly connect the four TX and RX to the four wires in the cable and shield to the shield of the cable at the coil end. Suspect its something to do with the epoxy and coil shell material and cable combination used. Original brown Tesoro coils are made out of a conductive plastic.

[bernte_one]

one choice was belden 2738 cable (2 twisted pair with one shield)
other choice can be dual s-Video cable These are two coax lines and one additionel shield line
or you take some simple microphone cable with at least 5 lines inside

but best choice could be a dual coax for sattelite or tv Installation
but not the stiff choice but with rubber
the tx and rx side is separated side by side and each pair with good shield
lorenz in Germany use such a Kind for their rx/tx pi coil - it can´t be wrong

http://www.nuggets.at/bilder/produkte/gross/Lorenz-26-cm-10-DD-Coil-SuchSpule.jpg