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Subject:
From:
Inge Hernefjord <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Inge Hernefjord <[log in to unmask]>
Date:
Fri, 12 Aug 2016 23:12:44 +0200
Content-Type:
text/plain
Parts/Attachments:
text/plain (240 lines)
Carl, your humor is best class ....“the major cause of problems is . . .
solutions.”

On 12 August 2016 at 15:34, Carl Van Wormer <[log in to unmask]>
wrote:

> #4 - Our customer is assuming the noise problem cannot be solved at the
> noise source.  They do not have control of the motors and VFD motor drive
> that may be attached to their systems, so the variety of the noise sources
> may be infinite.
>
>
>
> #3 - I do not assume the solution will be easy or even guaranteed, but the
> initial experiments in balancing the trade-offs shows promise.
> Implementation gets me into the realm of “the major cause of problems is .
> . . solutions.”
>
>
>
> #2 – After I explain my job to somebody and how I enjoy my work week, I
> usually end with “. . . and they pay me for it!”
>
>
>
>
>
> I’m glad it was a slow TechNet week, allowing me to receive a lot of
> attention and suggestions.
>
>
>
> 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
>
>
>
>
>
> *From:* Inge Hernefjord [mailto:[log in to unmask]]
> *Sent:* Friday, August 12, 2016 12:54 AM
> *To:* TechNet E-Mail Forum <[log in to unmask]>; Carl Van Wormer <
> [log in to unmask]>
>
> *Subject:* Re: [TN] looking for medium resistance material
>
>
>
> Carl,
>
> !. Admire you. What you do is real engineering.
>
> 2.You must have rare position and a generoujs boss.
> 3.I hope you are aware of how easily time and contract runs away. You may
> meet unexpected obstacles on the way to a tested an d approved component.
> 4. You did not react on my q wheater you could solve the problem by
> minimize the noise at the source.
> 5. You present , very openly, details that already may have been sent back
> to the Big Copiator. You may be on a hot spot, noise reduction is one of
> the most discussed topics in the SPACE industry, meterology, Medecine and
> other Hitech industries. Just a reminder....don't give 'them' to much
> goodies...
>
> /  Inge
>
>
>
> On 11 August 2016 at 18:06, Carl Van Wormer <[log in to unmask]>
> wrote:
>
> Since it's a slow TechNet morning, I thought I'd give an update on my
> recent experiment: (feel free to delete if you have real work to do).
>
> I obtained a sample of metalized Mylar that was hiding inside of a 3uF
> yellow capacitor.  I prepared a test capacitor made from two 1" square
> pieces of Copper tape attached to two business cards (for insulation and
> alignment) and then ran some 30 gauge wires from opposite corners for
> measurement attachment leads.  I named these two cards plate #1 and Plate
> #2.  I prepared a third business card with 2" square of Copper tape (shield
> #1), a fourth card with a 2" circle of a shiny metal stick-on silver award
> star (shield #2), and a fifth with a 2" square of the metalized Mylar from
> the sacrificial capacitor (shield #3).  I stacked up the test jig with the
> sandwich of plate #1, shield #1, and plate #2, and then measured about
> 10pF.  When I connected the guard terminal of my ESI VideoBridge 2100 to
> shield #1, the capacitance reading dropped to about 0.2pF, showing that the
> shielding was effective.  Repeating the measurements with the silver star
> and the capacitor film shields gave similar shielding effectiveness.  It
> was difficult to make a reliable connection to the capacitor film, but when
> the contact was made, the shielding was effective.
>
> Capacitive shielding effectiveness: Good!
>
> To test the effect of the shield material in a magnetic field, I used the
> two ferrite cores and a 100-turn coil similar to the final product.  The
> cup-cores are separated by about 1mm, and my business cards are about 1/3mm
> thick.  Measuring the inductance of the coil in the cup-cores with a
> 3-business-card spacers in the gap, I got an inductance of about 780uH with
> Q=77.  Inserting the Copper tape card (shield #1) in place of one of the
> spacers gave me an inductance of 255uH with Q=2.5 (the Copper is acting
> like a shorted turn).  Similar testing of the silver star sticker (shield
> #2) gave an inductance of 630uH with Q=2.9 (I guess the metal on the
> sticker is thicker than I thought).  When I inserted the card with the
> metalized Mylar (shield #3) into the gap-stack, the inductance measured
> 760uH with Q=68.  This showed very little degradation to the magnetic
> system.
>
> Magnetic transparency: Good!
>
> Metalized Mylar shows great promise as a solution to my problem, probably
> because the thickness is quite thin compared to the calculated skin effect
> depth of about 0.08mm at 1MHz.
>
> Now the problem comes down to making a reliable electrical connection to
> the metalized Mylar.  I am open to any suggestions as to effective ways to
> physically connect the metalized Mylar to my system, for positional and
> electrical attachment of the shield.  I'm hoping to hear of proven
> techniques (Conductive epoxy, ultrasonic welding, etc.) that have been
> successfully used for reliable electrical and mechanical mounting and
> attachments.
>
> 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: Carl Van Wormer
> Sent: Wednesday, August 10, 2016 7:42 AM
> To: TechNet E-Mail Forum <[log in to unmask]>
> Subject: RE: [TN] looking for medium resistance material
>
> I found that a capacitive shield plate connected to ground through a 100
> Ohm resistor would eliminate the VFD noise effects.  Changing the resistor
> to 1000 Ohms started to show some interference.  I'm hoping that a flimsy
> Mylar conductor (around 1 Ohm per square) would be a sufficient shield for
> the electrical field coupling (the gap between the 2 coils is a couple of
> mm).
>
> As the old guy in the ESI repair department would say . . . "One
> experiment is worth a thousand expert opinions."
>
> 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: Louis Hart [mailto:[log in to unmask]]
> Sent: Wednesday, August 10, 2016 7:28 AM
> To: TechNet E-Mail Forum <[log in to unmask]>; Carl Van Wormer <
> [log in to unmask]>
>
> Subject: RE: [TN] looking for medium resistance material
>
> Carl, if the conductor thickness is less than the skin depth, would that
> mean the magnitude of the evanescent wave electric field would be great
> enough to allow propagation outside the shield?  Sorry to say, my
> understanding of electromagnetic field theory is a lot less than what I
> think it should be, but I am curious.
>
> Regarding aluminum and soldering, I knew a guy who had a roll of 'aluminum
> solder' on his desk although I never saw him use it.  The wire was several
> millimeters in diameters, so may not have been for electronic purposes.
>
> On the subject Drew brought up of mu-metal, I inherited a microwave
> spectrometer long ago which had a klystron housed in the stuff. The fellow
> who bequeathed it to me said the metal was great for shielding, but its
> desirable properties were degraded by mechanical forming.
>
> Nice to see good activity on TechNet.  (I may qualify as one of the
> old-timers, having joined when it first appeared back in 1994 or 1995.)
> Louis Hart
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl Van Wormer
> Sent: Wednesday, August 10, 2016 9:16 AM
> To: [log in to unmask]
> Subject: Re: [TN] looking for medium resistance material
>
> 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
>
>
>

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