You don't you use conductive epoxy
Best regards,
John Burke
> On Aug 10, 2016, at 6:15 AM, Carl Van Wormer <[log in to unmask]> wrote:
>
> My next attempt will be to try a metalized Mylar, hoping that the thin conductor (much thinner than the skin effect depth) will be good enough for the capacitive shielding, but too thin for significant eddy current flow from the magnetic field. If that work, I will be left with the "simple" matter of connecting to the shield. How do you solder a wire to a party balloon?
>
> Thanks,
> Carl
>
>
>
> Carl B. Van Wormer, P.E., AE7GD
> Senior Hardware Engineer
> Cipher Engineering LLC
> 21195 NW Evergreen Pkwy Ste 209
> Hillsboro, OR 97124-7167
> 503-617-7447x303
> [log in to unmask] http://cipherengineering.com
>
>
> -----Original Message-----
> From: Torsten Hagge [mailto:[log in to unmask]]
> Sent: Tuesday, August 09, 2016 11:31 PM
> To: TechNet E-Mail Forum <[log in to unmask]>; Carl Van Wormer <[log in to unmask]>
> Subject: AW: [TN] looking for medium resistance material
>
> Hi Carl,
>
> Try to experiment with copper or nickel spray (google: Super Shield Conductive Coating 841/843), short sprays on capton tape through some kind of mesh...
>
> Take care,
> Torsten
>
>
> Best Regards
>
> KRISTRONICS GmbH
>
> Dipl.Ing. (FH) Torsten Hagge
> team leader HW development
> Gewerbegrund 5-9
> 24955 Harrislee
> Telefon +49 (0) 461 7741-624
> Telefax +49 (0) 461 7741-642
> [log in to unmask]
> www.kristronics.de
> Place of jurisdiction: Flensburg, commercial register: HRB 1433 FL CEO Dipl.-Ing. oec. Thormod Ohm VAD-Id DE 811182059 Bank account: Deutsche Bank AG Flensburg, account 4216610, bank number 21570011
> IBAN: DE32 2157 0011 0421 6610 00, BIC: DEUT DE HH 215 Please consider the environment before printing this e-mail
>
>
>
> -----Ursprüngliche Nachricht-----
> Von: TechNet [mailto:[log in to unmask]] Im Auftrag von Carl Van Wormer
> Gesendet: Dienstag, 9. August 2016 17:12
> An: [log in to unmask]
> Betreff: Re: [TN] looking for medium resistance material
>
> The longer story is (feel free to ignore this if you don't care about the background details):
>
> My short term goal is to set up an experiment to see if a shield of intermediate resistance will address my present condition. We all know that the major cause or problems is . . . solutions.
>
> The inherited problem system is used to transfer power (5W-10W) during Phase 1 of operation, and to transfer acoustic signals (Piezo pickup, 10kHz to 1MHz) daring Phase 2 of operation. The 100 turn, 15mm diameter coils were mounted inside of ferrite cup-cores with a gap between the 2 halves of the cores. One core-half was mounted in a fixed aluminum housing, while the other was mounted in an aluminum housing at the end of a rotating shaft (on axis) with a gap between the cores of about 1mm.
>
> I came in to solve a noise pickup problem on the received acoustic signal which was caused by a VFD motor speed controller. The symptoms could be simulated on the bench by connecting a 3kHz, 5V signal generator square wave to the rotating housing. In the classic “fix it, but don’t change hardly anything” request, I found that I could shield the receiving coil (inside the core) with some copper foil tape (leaving a gap to avoid the “shorted turn” effect). This eliminated the effect of the capacitive coupling on my test bench. During the implementation phase, I found that we still had some noise that was traced to the capacitive coupling on the rotating (source) side. Since the coils were not differential (one end of each was connected to local ground), the asymmetrical coupling signal caused a current to flow in the transmitting coil that magnetically coupled to the receiving coil. Adding a shield to the rotating coil addressed that noise injection method. The system was pronounced “Good.”
>
> We have found that the Phase 1 power transfer efficiency is reduced in the shielded systems. Eddy current losses in the shield seem to be the cause, so I’m looking for ways to reduce those losses in my environment. Raising the resistance of the shield material seems to be a simple solution, as long as the resistance is low enough to provide effective shielding. Unfortunately, I’ve been unable to find some easy to acquire samples of various resistive sheets to play with. I was hoping to do some easy experiments to see if my resistive based shielding approach stands up to my first set of experiments before I started the process of defining a material to be used. I’ve found some conductive ABS filament (http://www.makergeeks.com/coabs3dfi10.html) that might work if I can find somebody to print a plate and a method to electrically connect to it, but I don’t know a local friend with a 3-d printer.
>
> I’m still hoping for the sample kit of sheets of various resistivity materials, but I haven’t found the right page in the Digi-Key catalog . . .
>
> Thanks for any suggestions,
> Carl
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
> Sent: Tuesday, August 09, 2016 5:55 AM
> To: [log in to unmask]
> Subject: Re: [TN] looking for medium resistance material
>
> There is just about every type of material with just the right properties you are looking for available as a 3d printing medium.
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Mike Fenner
> Sent: Tuesday, August 09, 2016 12:44 AM
> To: [log in to unmask]
> Subject: Re: [TN] looking for medium resistance material
>
> Very kind of you Inge, but this is not really my cup of tea these days. I am aware that there are a number of suppliers of carbon based inks and these can be tailored to produce desired sheet resistivity ranges. That sort of thing is widely used on flex circuits and additive (printed electronics) circuitry. I would think internet searching should bring up a good candidate list of suppliers in a few iterations . There is cross over here to ESD protection products, so that would be a good search area also.
>
> ---
> Regards
>
>
> Mike
>
> www.chrisfennerfund.org
> www.facebook.com/chrisfennerfund/
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge Hernefjord
> Sent: Sunday, August 7, 2016 10:37 AM
> To: [log in to unmask]
> Subject: Re: [TN] looking for medium resistance material
>
> Carl,
> when I was active I used to contact SemiAlloys. I needed certain resistivity in lids for resistivity pulsed current seam welding of small packages for missiles. We produced about 50,000 pcs from SemiAlloys with
> He/Kr10 exp -10 with succcess. Mike Fenner has more to say , I think..
> They are extremly nice to cooperate with. Mike as well, despite he is english.
>
> Semi Alloys Inc
>
> 888 S Columbus Ave
>
> Mount Vernon, NY 10550
>
> (914) 664-8318)
>
>
>
> Good Luck / Inge
>
>
> On 7 August 2016 at 05:40, Carl Van Wormer <[log in to unmask]>
> wrote:
>
>> I usually want my physical structural resistances to be as low as
>> possible
>> (conductors) or as high as possible (insulators). Now I need an
>> intermediate resistance, probably in the range of 100 to 1000 Ohms per
>> square. The application will be an electrostatic shield in an
>> alternating field, hopefully balancing magnetic heating losses against
>> capacitive shielding effectiveness.
>> I have never seen these materials offered from any of my normal
>> sources, but I’m sure that there is something out there that will
>> work. It could be sheet materials, paints, or slightly conductive
>> epoxies, or something else I haven’t thought of. Since there is a
>> very wide experience base on this site, I’m asking here first.
>> Any suggestions will be appreciated.
>>
>> Thanks,
>> Carl
>>
>>
>>
>>
>> Carl B. Van Wormer, P.E., AE7GD
>> Senior Hardware Engineer
>> Cipher Engineering LLC
>> 21195 NW Evergreen Pkwy Ste 209
>> Hillsboro, OR 97124-7167
>> 503-617-7447x303
>> [log in to unmask]<mailto:[log in to unmask]>
>> http://cipherengineering.com<http://cipherengineering.com/>
>>
>> This message may contain confidential and/or proprietary information,
>> and is intended for the person/entity to whom it was originally
>> addressed. Any use by others is strictly prohibited. If I sent this
>> to you by mistake, please be nice and delete it, and then tell me of
>> my mistake so I can send it to the right person.
>>
>>
>>
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