3M Scotch 24 Copper Mesh Electrical Shielding Tape

[Tibuck19]

hey guys, I have a small account at 3M Canada and I was thinking of getting some 3M Scotch 24 Copper Mesh Electrical Shielding Tape, I would have to order a case of 10 Rolls of 1" 15 feet, I would be able to sell of at least 8 rolls from the case if anyone would interested. Price would be $30.50 a roll CAD = 25$ USD plus shipping which should be in the 5$ range from Canada to USA. But if any of you want a 100 Foot roll I can get those too. Just drop me a PM if you'd like one. I also have 16 recycled 16X2 LCD displays for those who want to make VID for their detectors. if you take a roll of tape I would sell the LCD for 2$.

[rickb]

What do you plan to shield with it?

[Tibuck19]

What do you plan to shield with it?

A fast mono coil for small gold for my MMP using the method described by Mr Rogowski AKA bbsailor is the first one I will attempt with it.

[rickb]

That is for electromagnetic shielding. If you want something for electrostatic shielding, use graphite paint. Metallic shielding will distort the tx field and worsen rx sensitivity. Surface resistivity of 1-2Kohm/square will work, but even higher figures that still eliminate electrostatic pickup would be better. Spray cans of graphite paint are available.

From a previous post.

Ohms per Square

"The resistance of any square area of thin film resistive material as measured between two parallel sides.

A unit of resistivity for surface films and other materials whose thicknesses are considered to be negligible.

The resistivity of a very thin conductor is defined to be its resistance (in ohms) multiplied by its width and divided by its length. If the conductor is square in shape, then its length and width are the same and its resistivity is simply equal to the resistance of the square. Whatever the size of the square the number will be the same.

The distance unit is lost in the division, but convention uses Ohms per Square to describe the nature of the unit and measurement."

I bought a gallon of water based alkyd graphite paint. It has about 600 ohms/sq. Thinning it with water or another non conductive alkyd paint will result in higher resistance/sq. It will require some experimenting.

The original purpose of the paint is to provide a very slick non-stick surface when dry. Its used to coat the underside of lawn mowers, or most any kind of powdered or granular material handling equipment to promote free movement of the stuff. I will use part of it on my mower. It was $27/gal.

Rick

[homefire]

This works fine for most Mono and DD coils for me. https://www.banggood.com/10mm-X-20m-EMI-Copper-Foil-Shielding-Tape-Conductive-Self-Adhesive-Tape-p-1107008.html?rmmds=buy


Would this be a better option ? http://www.newark.com/te-connectivit...14_US%2Fsearch

[bbsailor]

A fast mono coil for small gold for my MMP using the method described by Mr Rogowski AKA bbsailor is the first one I will attempt with it.

Here is a refinement of the method to use Scotch 24. Cut the Scotch 24 so you only use a single layer. Measure the circumference of the wire bundle from a cross section view. You do not want to wrap the Scotch 24 around to make the wire touch and form a cross section conductive loop. Use electrical tape and place an overlay on top of the Scotch 24 or cut the Scotch 25 just wide enough to lie as a single layer with a slight gap on the top of the coil. When using very low delays this method will minimize the Scotch 24 being seen as a target. Use the normal Scotch 24 shield gap where the coil lead wires enter and exit the coil.

Just like a gold ring that is fully conductive around it's circumference can be detected at a long distance but a ring that is broken will only be detected at a much shorter distance. This should help you form a good mental model for the best way to use Scotch 24 on a PI metal detector coil.

I hope this helps.

Joseph J. Rogowski

[Tibuck19]

Here is a refinement of the method to use Scotch 24. Cut the Scotch 24 so you only use a single layer. Measure the circumference of the wire bundle from a cross section view. You do not want to wrap the Scotch 24 around to make the wire touch and form a cross section conductive loop. Use electrical tape and place an overlay on top of the Scotch 24 or cut the Scotch 25 just wide enough to lie as a single layer with a slight gap on the top of the coil. When using very low delays this method will minimize the Scotch 24 being seen as a target. Use the normal Scotch 24 shield gap where the coil lead wires enter and exit the coil.

Just like a gold ring that is fully conductive around it's circumference can be detected at a long distance but a ring that is broken will only be detected at a much shorter distance. This should help you form a good mental model for the best way to use Scotch 24 on a PI metal detector coil.

I hope this helps.

Joseph J. Rogowski

If you look at my photo's , they show how I make the " bobbins " which I spin my wire around, it is made of ABS printed form, then it gets a insert to tighten them bundle together. If im getting what you said right, I do not wrap the tape like I would electrical tape but more like on of the photos starting with length of A then B and so on ?

[Tibuck19]

This works fine for most Mono and DD coils for me. https://www.banggood.com/10mm-X-20m-...html?rmmds=buy


Would this be a better option ? http://www.newark.com/te-connectivit...14_US%2Fsearch

Hi Homefire, sorry for the long reply delay, I ve been a busy bee, I have the same copper tape I will also try that to compare it to the 24tape. Thanks

[bbsailor]

If you look at my photo's , they show how I make the " bobbins " which I spin my wire around, it is made of ABS printed form, then it gets a insert to tighten them bundle together. If im getting what you said right, I do not wrap the tape like I would electrical tape but more like on of the photos starting with length of A then B and so on ?

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Please tell me the cross section size of the square outside and inside area for the wire. If you try the Scotch 24 mesh shield and a more solid copper shield, measure the capacitance between the shield and each of the coil wires.The Scotch 24 should be lower capacitance due to less surface area. If you wrap the shield clockwise starting at the lower end of A and end the shield on the lower parallel edge to B just adjacent to the shield start point, that should work and keep a good space between the shield and the coil wire to keep the coil to shield capacitance low.

Joseph J. Rogowski