Is it possible to to block the disturbingsignal by genedrating  same signal
but 180 degrees phase delayed? Like eliminating Tinnitus../Inge

On 10 August 2016 at 10:09, Inge Hernefjord <[log in to unmask]> wrote:

> Gosh, TN isn't declining as I thought. Your challenge seems to place in a
> research  lab. When I ran into ssuch problems and the solution proposals
> grew until I couldn't decide which one to test (as usual you are expected
> to do the job over a night and with no money) then I use go back and ask
> myself if there might be another concept. Background noise is a plague and
> many a time nearly impossible to eliminate. Therefore I wonder if not the
> cheaapest and fastest way is to modify the noise source. B&O had a similar
> issue with their studio recorders. They eliminated the problem by
> encapsulate the motor in my-metal. The S/N lowered by one magnitude.  Just
> a thought. Labbing with various resistiviity stuff can be expensive a
> case.../Inge
>
> On 9 August 2016 at 17:11, Carl Van Wormer <[log in to unmask]>
> wrote:
>
>> 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.
>> >
>> >
>> >
>>
>
>