Perhaps you should provide some details such as expected load, frequency
range and so on. One should expect that one's choice of equipment and
manufacturer will be different if one is shaking a military tank, than
if one is shaking a small electronic module, for example.
Bob Wilson
TIR Systems
The only problem is that a utility transformer may have high energy
density, but it has little more flux density than the smallest
wall-wart.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Scott Douglas [mailto:dougl...@naradnetworks.com]
Sent: June 14, 2002 10:06 AM
In other words you are suggestion to cure the disease itself, and not
just the symptom.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: JP Hare [mailto:john.p.h...@verizon.net]
Sent: June 13, 2002 4:50 AM
To: Anchondo, Dan; emc-p...@majordomo.ieee.org
Subject: RE:
Best use of a Stirling engine I have seen, was implemented by a friend
of mine in Germany about 15 years ago. He added a miniature Stirling
engine he had made (it could be held in one's hand) to his butane
powered barbecue grill. The heat of the grill drove the Stirling engine,
which in turn
Seems to me that the court could better use its time to nail some of the
el-cheapo products from the far east made by manufacturers that just
stick a CE mark on everything they make as part of the graphics
design. I have seen numerous such products that haven't a hope of
getting CE approval,
On the surface, it seems to me that that requiring any sort of
regulatory compliance for a device operating from a 3 Volt source would
be utterly absurd. But then, from my perspective, regulatory agencies
are not always noted for their use of common sense in creating their
regulations. The fact
of ferrite used, is the cause of the excessive rate of
change of temperature.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Robert Macy [mailto:m...@california.com]
Sent: June 6, 2002 11:06 AM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: Re: ferrite transient
.
Susan Beard
Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on
06/04/2002
02:16:48 PM
Please respond to Robert Wilson robert_wil...@tirsys.com
Sent by:owner-emc-p...@majordomo.ieee.org
To:shbe...@rockwellcollins.com, emc-p...@ieee.org
cc:
Subject:RE: ferrite transient
literature on the use of ferrites does not address these types
of transients.
Susan Beard
Robert Wilson robert_wil...@tirsys.com@majordomo.ieee.org on 06/04/2002
02:16:48 PM
Please respond to Robert Wilson robert_wil...@tirsys.com
Sent by:owner-emc-p...@majordomo.ieee.org
To:shbe
Your question is not all that clear. It appears to imply that transients
have an affect on the ferrite beads, but it is the other way around
(maybe that is what you meant). But in general, small ferrite beads have
little effect, except at very high frequencies (hundreds of MHz), unless
they are
In designing power supplies, it is common to use nominal mains voltage
+/-15% (e.g. in North America, 115 +/-15%, or 98V to 132V) as a design
guideline. The same +/-15% is generally true for European 230 V designs.
Thus, using +/-10% for Japan seems a little skimpy. Given the rather odd
on them if you are interested,
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Chris Wells [mailto:cdwe...@stargate.net]
Sent: June 4, 2002 5:11 AM
To: Robert Wilson; EMC-PSTC Discussion Group
Cc: christopherdwe...@eaton.com
Subject: Re: Bonding to conductive plastic
Are those rather irrational AWG sizes even recognized by TÜV or VDE? Most of
the rest of the world hasn't a clue what they mean.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Anchondo, Dan [mailto:danch...@ciena.com]
Sent: June 3, 2002 11:15 AM
To:
The problem you are encountering is made somewhat more difficult by the
very low amount of metal in the polycarbonate resin. Reasonable
shielding generally requires higher than 20% metal in the mix (35% is
not uncommon).
But to answer your questions:
- The type of screw is relatively
The first of your suggestions will not work with the material Chris is
using. Any polymer that has conductive material mixed in, tends to form
a thin skin of pure resin at its surface. A conductive paint or epoxy
applied to the surface will not come in contact with the metal strands,
and all you
Steel, nickel, and zinc are all relatively poor conductors, at least as
compared to copper or aluminum. Of these, the best conductor is zinc.
But in your application the type of metal to use as plating is clearly
irrelevant, since the plating will carry very little current. Almost all
of the
Warum kannst du nicht Deutsch verstehen?? (heh heh)
It means cube shaped or cubic. The sentence means (as much as one can tell
in such an abbreviated piece) about (or for, or with relation to) a cubic (or
cube shaped) volume of 27 liters...
Bob Wilson
TIR Systems Ltd.
Vancouver.
Yes, a switchmode power supply falls under FCC part 15. Also, if by
timing signals you are referring to its switching frequency, I think
you have lost a zero somewhere. No switchmode power supply operates in
the audible frequency range around 9KHz or 10KHz (especially one used to
operate a
: May 24, 2002 1:53 PM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: RE: Coaxial Switches - use with spectrum analyzer and gear?
This may not be the effect being referred to, but...
Relays require a ferromagnetic alloy, such as Kovar for the contacts.
The
leads leading to the connector
As it is stated, below -20dB, nothing at all comes through the switch.
Then once you reach that level, output signal level suddenly begins
increasing from zero. That obviously makes no sense and is probably only
a result of an engineering spec being lost in translation when Marketing
created the
Oddly enough, in Switzerland (and Germany, Austria etc.) they aren't
called cellphones. They are called Handys. Part of a new language
called DENGLISH (Deutsch + English). Useless fact-of-the-day.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: IEEE-EMC User Group
Hmmm. the most politically correct engineer that has any brains
Politically correct and having brains? Aren't the two mutually
exclusive?
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Jim Freeman [mailto:free...@chelsio.com]
Sent: May 16, 2002 11:17 AM
To: Berkley
Stating the proven principles of accurate thermal analysis is hardly
muddling the knowledge pool.
No one has suggested that increased resistance leads to increasing heat
generation in an infinite spiral as you mention. This would obviously be
nonsense, and is not predicted by theory or observed
Maxwell [mailto:chris.maxw...@nettest.com]
Sent: May 13, 2002 2:09 PM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: RE: Constant for Change of Resistance formula.
Bob,
I read your initial response to this thread; and I think that your
understanding of the situation is more complicated than
?
Regards
Chris Colgan
Compliance Engineer
TAG McLaren Audio Ltd
The Summit, Latham Road
Huntingdon, Cambs, PE29 6ZU
*Tel: +44 (0)1480 415 627
*Fax: +44 (0)1480 52159
* Mailto:chris.col...@tagmclaren.com
* http://www.tagmclaren.com
-Original Message-
From: Robert Wilson [SMTP:robert_wil
What are the units? 234.5 ...what?? Looking at what the units are, will
basically tell you exactly what the property is related to.
Nonetheless, you cannot possibly directly determine what the temperature
change of something as physically and geometrically complex as a
connector, merely by
Going around corners presents another interesting problem, depending on
the orientation of its axis. The vacuum chamber that such a flywheel
must operate in (to make it practical) presents another interesting
challenge.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From:
No need to worry. First, a CD can be spun at many tens of thousands of
RPM without destruction. But more importantly, the spin ratios are not
straight multiples of the basic disk RPM. After all, if this were true,
the 300 to 400 RPM maximum speed of a 1X CD player, would be 19,000 to
25,600 RPM,
Crime rates drop drastically in nations where guns are freely owned by
the PUBLIC?? I suppose this explains why the US has a murder rate some
10 to 20 times that of western Europe, and whose extreme violent crime
rates make it a pariah in the eyes of so many other nations? And where
do you think
Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Dave Lorusso [mailto:dave.loru...@genband.com]
Sent: May 7, 2002 7:30 AM
To: Robert Wilson
Cc: emc-p...@ieee.org
Subject: RE: What Every Startup Needs to Know About NEBS
I showed a film clip of failing the fire resistance test
Free men own guns. Yeah right. The true mark of a civilized country is
that its citizens all own guns. Never been anywhere else, have you? It
is just this sort if immature 19th century frontier mentality that is
embarrassing the US in the eyes of the rest of the world.
Bob Wilson
TIR Systems
You never showed photos of the NEBS flame test! Nothing like burning
your equipment to a crisp with a 1 foot high flame from a line burner,
for good entertainment :)
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Dave Lorusso [mailto:dave.loru...@genband.com]
Sent:
Regarding the perforation of the aircraft by bullets, and the supposed
gradual depressurization that should occur, it might be worth
remembering the disaster of the world's first fleet of jet passenger
aircraft, the British Comet. In the early 1950s they were falling out
of the sky in some
...at least not North American trains, whose technology and
infrastructure has fallen embarrassingly far behind that of much of the
rest of the world.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: lisa_cef...@mksinst.com [mailto:lisa_cef...@mksinst.com]
Sent: May 3,
I wouldn't get too paranoid about it. You are probably far more at risk
on the ground in any US city, where a substantial number of people on
the street are packing heat.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Gregg Kervill [mailto:gkerv...@pgtv.net]
Sent: May
I have a general question regarding power factor limits relating to the
design of off-line switchmode power supplies.
We will be starting the design of a relatively simple, off-line
switchmode power supply that will be used to power an LED Luminaire (for
lighting up the outside of buildings). A
With regards to the need to subject something running from a 9V
battery to a battery (pun not intended) of safety approvals, to me
this shows how some aspects of regulatory control are just a solution
searching desperately for a problem. There are times when it seems to
me that the entire
is available free at www.pmail.com
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Robert Wilson
Sent: April 24, 2002 11:37 AM
To: emc-p...@ieee.org
Subject: RE: A very nice game
All of which makes one wonder why one would ever use IE as a mail
reader! Rather like using
For what it's worth, an absolutely excellent virus purge program is
F-Prot, available from Frisk Software International at:
http://www.f-prot.com/f-prot/download/
The DOS version is FREE and supported with very frequent (almost weekly)
virus signature file updates. It runs just fine in a DOS
, and it is
free for the download.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Douglas C. Smith [mailto:d...@emcesd.com]
Sent: April 24, 2002 10:36 AM
To: Robert Wilson
Cc: emc-p...@ieee.org
Subject: Re: A very nice game
Robert,
You do not have to open the attachment
Just as a matter of curiosity, regarding the trailing boilerplate on
your message, what could possibly be accomplished by forwarding an
incorrectly delivered email back to the sender? The recipient will still
have the original message. Sounds like someone isn't too clear on the
concepts of
In spite of the attachment having been removed by the system, it was
pretty darned obvious what this must have been. It always amazes me that
people are foolish (stupid?) enough to open attachments to obviously
suspicious emails like this one, that are from people they don't know,
and subjects
Just to keep the record straight, Kapton is a polyimide, not a
polyamide. They are vastly different. Polyamide is the general name for
the family of polymers commonly referred to as Nylon.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Scott Lacey
A lot depends on the frequency you are operating at. A low frequency filter may
use electrolytic caps, for example, and there is no way you will ever get 180°C
electrolytics! Most of the common non-electrolytic capacitor dielectrics won't
have a hope of operating at this temperature either.
Not sure this would be a cure in this instance. This is effectively the
same as adding a lossy inductor in series with the cap, which would tend
to negate any benefits of using a cap with lower self inductance.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From:
Capacitors can continue to function quite well above their self
resonance. You should not be worrying about choosing a cap based on self
resonance per se.
However, it is standard practice to parallel a 0,1 uF bulk bypass cap
with a much smaller NP0 or C0G type (say 470 pF or 1 nF), especially
This may seem like a dumb question, but how would a cellphone pose a
hazard? I am unaware of anything in a cellphone that can cause any kind
of a spark or arc that might start combustion in such an atmosphere.
Certainly none of the keypad contacts could cause a problem.
Bob Wilson
TIR Systems
...@uk.thalesgroup.com]
Sent: February 21, 2002 12:32 AM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: RE: South Korean Power System Schuko Plugs
Hi Folks
A few years ago I worked for BSI Technical Help to Exporters and
helped to
update their publication World Wide Plugs and Sockets Survey
Since the Japanese use the North American style plug (seems an odd
choice since it is so flimsy in comparison to other types they could
have used), it's probably a good bet that the Koreans us this as well.
I'd be surprised if they used the Schuko plug.
Bob Wilson
TIR Systems Ltd.
Vancouver.
One of the Japanese islands also has a 50Hz power grid. Apparently it's
a real dog's breakfast there, as far as AC power systems are concerned.
The voltage is 100 V, not 110V (as the original poster had mentioned).
Bob Wilson
TIR Systems Ltd.
Vancouver.
With regards to beryllium fingers, they are not beryllium. They are an
alloy of copper and beryllium, with the standard C17000 alloy containing
only 1.7% beryllium.
There is no danger in simply handling these fingers. To be sure, there
is a danger in breathing in dust from machining actual
I suspect that this will depend very strongly on the characteristics of
specific type of resistor. Further, there will undoubtedly be very
significant differences from manufacturer to manufacturer, in the
ability to absorb stresses well beyond normal design intent. I think it
would be rather hard
Without getting into details, the main point is that it is brutal (and
even that is an understatement), and it is expensive. A full-on test
involves everything from EMI compliance, to earthquake testing, to flame
and fire tests. Costs can easily run to US$100,000 and time to do the
test can range
If this is what you feel in necessary at moderate frequencies (I believe
the original discussion was related to 600 MHz), I'd hate to see what
you might feel is required at high frequency. :)
The idea of chip in board that you mention is not new. It was first
tried in the Far East some years ago
Clearly, we need to ensure that lighting carries the appropriate
regulatory warnings! A couple of paragraphs of the usual rambling UL/CSA
warnings and cautions should do the trick. :)
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: geor...@lexmark.com
Yeah, blame John! :)
For what it's worth, in the 25 years I have been involved in the
mechanical packaging design of electronic enclosures, I have never heard
of the word faying. One can't help but wonder if someone just
misspelled facing.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original
Some answers to your questions:
- Star washers (internal, not external) will cut through any normal paints,
including powder paints. I have never seen a situation where fully tightening a
screw would fail to make a good connection if an internal tooth lock washer was
used. But having said
Could this be a weird abbreviation for Signal to Noise ratio?
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: richwo...@tycoint.com [mailto:richwo...@tycoint.com]
Sent: March 21, 2002 7:29 AM
To: emc-p...@majordomo.ieee.org
Subject: SND/ND ratio
The term SND/ND ratio
I generally agree, although your comment that double sided PCBs are
about to disappear is rather premature. Way over half of the PCBs
manufactured in the world today are SINGLE sided (look in any piece of
high volume electronics). Double sided PCBs still will be used in volume
for many years to
I've had a fair amount of experience with both conductive plastics, and
conductive coatings. Your comments are basically correct.
A lot depends on what you are trying to achieve, both in terms of
attenuation at a particular frequency, and how much actual attenuation
you need. In one project I
One solution that would soon get rid of the problem at its source,
would be to have the Marketing Moron do a few of the upgrades himself.
With any luck, he would find out firsthand the effects of electrical
current flow through the human body. :)
Bob Wilson
TIR Systems Ltd.
Vancouver.
A trivially simple, non-costly pressure release mechanism is a piece of
.020 or 0.040 GoreTex sheet covering a vent hole (about half an inch
diameter). This will be totally waterproof to 4 meters depth (I
designed a patented hydrostatic release mechanism used on a popular
shipboard EPIRB rescue
Illogical bureaucracy perhaps?
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: POWELL, DOUG [mailto:doug.pow...@aei.com]
Sent: March 12, 2002 3:26 PM
To: emc-p...@ieee.org
Subject: Wire spool labeling requirements
Over the years, there is a question that has plagued
Once again, the legal system scores a victory over common sense!
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Bill Owsley [mailto:ows...@cisco.com]
Sent: March 8, 2002 7:15 AM
To: Doug McKean; ieee pstc list
Subject: Re: Don'r Get Caught Running a Red Traffic Light!
Keyboard Engineer?! That's a good one. Must remember that!
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Stephen Phillips [mailto:step...@cisco.com]
Sent: March 7, 2002 12:27 PM
To: Robert Wilson
Cc: emc-p...@majordomo.ieee.org
Subject: RE: EMC and Safety PCB
As a side issue to your comments, I find it interesting that you refer
to a PCB designer as a CAD engineer. Does this mean that 20 years ago
he would have been a Drafting Board engineer? :)
Kind of sad when the tool one uses is deemed to be more important than
the job one is doing!
Bob Wilson
And not least, for pole-mounted red light cameras, you need shotgun
protection. :)
The first red light camera installed here (Vancouver) was dealt with
rather quickly in this manner.
Bob Wilson
TIR Systems Ltd.
Vancouver.
-Original Message-
From: Robert Johnson
Regarding the comment John made (snipped below), I think that in some
regards, regulatory warnings are partially to blame for installers/users
not paying proper attention to safety requirements.
In North America, the tendency is to require verbose, rambling warnings
that tend to include so much
More importantly, North American paper sizes are just plain irrational.
At least the metric sizes all have the same aspect ratio, so
enlarging/reducing from one size to another doesn't result in a large
band of unused space. Even the US Patent Office has given up on US A
(8-12 x 11) or US legal
One must take care to separate fact from opinions. Mixing metals as
you mention is NOT necessarily a sure way to promote corrosion. Yes,
steel against aluminum us not good practice since they are far enough
apart on the electromotive series that they will act as a local battery
(in the presence
I can't verify the part that after a wrench was dropped on the -48V bus
bars, all the other equipment was blown, but I can throw a little light
on this. The previous company I worked for made Telco rectifiers. Our
largest system had an output of over half a megawatt (!) at -48V. The
bus bars were
: February 25, 2002 4:14 PM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: RE: PCB floating area layout
Jeeez, I have just the opposite problem GROUNDING a PCB at a
certain location.
The device is a metal enclosed digital device, about the size of
a video cassett tape. Its
Floating grounds on PCBs tend to be problematic, especially at high
frequencies. Minimizing the effective capacitive reactance between the
floating ground and the real ground will ensure that the floating
ground is AC Cold. I don't just mean bypassing it with (say) a few
thousand uF of
ANSI?? This is the same organization that has reinvented the well-proven
ISO-metric fastener standard and in the process, came up with the M6.3 screw.
What is a 6.3mm screw you ask? Why it's ¼ of course!
Another gem of their wisdom is they reinvented the traditional flat topped DIN
85 screw
: June 21, 2002 11:12 AM
To: Robert Wilson
Subject: Re: SI Unit for volume
Bob,
W/cc is multiple of KW/m^3.
1 KW = 1,000 W and 1 m^3 = 1,000,000 cc
therefore:
1 KW/m^3 = 1,000 W/1,000,000 cc = 0.001 W/cc or
1 W/cc = 1,000 KW/m^3
Robert Wilson wrote:
...
For example, in the latest Ferroxcube
Only if it applies to fluid volume. If it applies to volume of a solid,
then it is traditional to use cubic centimeters, or even m^3. The latter
is a heck of a big volume, and sounds almost silly, but it is
increasingly used. For example, in the latest Ferroxcube ferrite core
catalogue, specific
I cannot say if it is acceptable, because I am not sure what your
particular criteria for acceptability is. But I can say that there is
no problem technically.
In the company I previously worked for, we designed and made telco
rectifiers (basically they are honking big 48V battery chargers).
.
Vancouver.
-Original Message-
From: Ken Javor [mailto:ken.ja...@emccompliance.com]
Sent: June 20, 2002 6:31 PM
To: Robert Wilson; emc-p...@majordomo.ieee.org
Subject: Re: magnetic field measuring instruments and probes
I was simply reporting the military standard construction. I haven't
.
-Original Message-
From: j...@aol.com [mailto:j...@aol.com]
Sent: June 19, 2002 9:51 AM
To: Robert Wilson; mpet...@analogic.com; emc-p...@majordomo.ieee.org
Subject: Re: Transient Voltage Suppressor - Europe approvals?
In a message dated 6/19/2002, Bob Wilson writes:
Transzorbs (or TVSs
Transzorbs (or TVSs) are basically zener diodes that are rated for
their energy absorption capability. Since they are polar devices (i.e.
diodes) they are useless on an AC line. Well, I suppose you could put
two of them back to back, but this is not at all common. Typically,
these devices are
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