Copper wool

[William]

I would like to know if anyone has used this copper mesh wool for coil sheilding , its sold on ebay for pest control ? Thanks William

[kt315]

for electrostatic field protect it is incapacitated. you need in low conducting cover material like grafite etc.

cheers

[porkluvr]

If it is fresh it would probably work fine for the short run but unless it is plated or tinned it will corrode and conductivity will degrade.

Scotch 24 is a braided shielding that is tin plated and can be very effective. No, you do not necessarily need 100% coverage like KT315 suggested.

You've always got to consider that what works for shielding Inductance Balance coils may not be so good for PI coils. But you don't want either one to be corroding,

[William]

Thanks for the reply. How does the lead work for shielding on pi detectors? Thanks William

[porkluvr]

Asking me? "The lead"?

I suppose you are alluding to Scotch 24 braided shielding in an obscure way. Why that choice of words??
If you are going to tell me that #24 is coated with lead the element, well lead doesn't hurt anything.

If used skillfully, #24 can help enable faster PI flyback recovery (and finding small gold) by virtue of its contributing lower capacitance than some other types of shield would. It's kind of expensive for overall use, and graphite coatings as KT315 suggests can be much less expensive and plenty effective.

I said "# 24 can help enable", because using #24 by itself is not going to get you a fast coil. But a low capacitance shield can be icing on the cake (for finding small gold) if you have other necessary details worked out.

I am not going to tell you using that #24 is any better than a nice graphite coating. Instead you ask KT315 and maybe he will give you details of his technique. You make the comparison. Using graphite shielding is a more modern concept than using braid.

You need to do some research on Fast PI coils (there's a good article here), and graphite shielding.

edit: Accordion to Wikipedia, lead is a diamagnetic material and diamagnetic materials do have a slight bucking effect on a magnetic field. If you don't want that, don't use it.

[William]

lead

Hi Porkluvr, no I am speaking of just lead as a shielding, will it work well for a shielding?
Sorry I was not clear with my question. # 24 is real expensive so I'm looking for a good shielding that is inexpensive. THANKS FOR THE HELP WILLIAM

[Reg]

Hi William,

Yes, thin lead tape can be used for shielding. In fact, that is what Eric Foster used for years as his form of shielding material.

As to your question about the copper "wool" which is the copper mesh often used for dealing with pests, I can see no reason why it won't work. After all, Scotch 24 is copper mesh that has been tinned.

If you are patient, I suspect you will be able to find the Scotch 24 at a reasonable price on Ebay. In the mean time, you might try the copper mesh and see how it works.

In fact, I just may try it myself. So, thanks for the idea.

Reg

[Woody.au]

When using mesh you need to take into account the size of the spacing of the mesh, if it is not spaced far enough out from the coil winding then the ground capacitance to shield will also interact with the coil winding. The Copper should be Nickel plated to reduce residual eddy currents forming on the highly conductive copper. Maybe painting the Copper with losy Carbon / graphite may also help.

[William]

coper mesh

Thanks to everyone that replied to my post. I will give it a try.

[cyclops]

chemical tinning may be an option

I used chemical tinning for some of my PCB's, and it worked fine.
For tinning copper mesh, it should work too.
(here is a link, German and English: http://www.octamex.de/shop/download/...misch_Zinn.pdf

I guess that a local supplier over there may help you.
I found the base chemical ready mixed at a local supplier for electronics here.
If you know a little bit about chemistry, you may mix the chemicals for tinning by your own.

An electrolysis could work too, however I do not know which tin salt to use, which electrodes to use and the current to be applied... maybe a research on the net wmay help.