RE: SI Unit for volume

2002-06-24 Thread Robert Wilson
You're correct, of course. The problem is not lack of knowledge, but sloppy typing (something that I am an expert on). Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: bogdan matoga [mailto:bogda...@pacbell.net] Sent: June 22, 2002 5:55 PM To: Robert Wilson Cc: TM66

RE: SI Unit for volume

2002-06-22 Thread Robert Wilson
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 h

RE: SI Unit for volume

2002-06-22 Thread Robert Wilson
@rcn.com] Sent: 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

RE: SI Unit for volume

2002-06-21 Thread Robert Wilson
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 v

RE: Slotted Busbars

2002-06-21 Thread Robert Wilson
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

RE: magnetic field measuring instruments and probes

2002-06-21 Thread Robert Wilson
s Ltd. 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 ha

RE: magnetic field measuring instruments and probes

2002-06-20 Thread Robert Wilson
Litz wire at 100KHz sounds a little over the top. AWG20 or 30 will do the job nicely. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Ken Javor [mailto:ken.ja...@emccompliance.com] Sent: June 20, 2002 7:11 AM To: Istvan Novak; emc-p...@majordomo.ieee.org Cc: Istvan Novak

RE: Transient Voltage Suppressor - Europe approvals?

2002-06-19 Thread Robert Wilson
Ltd. Vancouver. -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: Transz

RE: Transient Voltage Suppressor - Europe approvals?

2002-06-19 Thread Robert Wilson
Transzorbs (or "TVS"s) 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 us

RE: vibration test system

2002-06-17 Thread Robert Wilson
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 Lt

RE: Magnetics testing

2002-06-14 Thread Robert Wilson
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 To

RE: Shielded DC Power Cable Vendors

2002-06-13 Thread Robert Wilson
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: Shield

RE: (off topic) Stirling cycle

2002-06-11 Thread Robert Wilson
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 opera

RE: DOC "Assembled from tested components"

2002-06-10 Thread Robert Wilson
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, pro

RE: Electrochemical potentials

2002-06-07 Thread Robert Wilson
Zinc against tin is certainly not a recommended combination. The base metals in this case are not relevant. What matters is the metals that will be in actual contact (i.e. the platings). The electrochemical potential between zinc and tin is about 0.7 Volts which is enough to get a nice corrosion r

RE: IEC 60950 & Solar Cells

2002-06-07 Thread Robert Wilson
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 th

RE: ferrite transient voltage/current response

2002-06-06 Thread Robert Wilson
me 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 tran

RE: ferrite transient voltage/current response

2002-06-06 Thread Robert Wilson
pulse. Most of >the standard literature on the use of ferrites does not address these types >of transients. > > >Susan Beard > > > > > > > >"Robert Wilson" @majordomo.ieee.org on 06/04/2002 >02:16:48 PM > >Please respond to "Rob

RE: ferrite transient voltage/current response

2002-06-05 Thread Robert Wilson
er the ferrite properties would be altered by the lightning pulse. Most of the standard literature on the use of ferrites does not address these types of transients. Susan Beard "Robert Wilson" @majordomo.ieee.org on 06/04/2002 02:16:48 PM Please respond to "Robert Wilson"

RE: ferrite transient voltage/current response

2002-06-04 Thread Robert Wilson
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 no

RE: Japan mains voltage

2002-06-04 Thread Robert Wilson
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 collection

RE: Bonding to conductive plastic - best method?? - BEST SCREW

2002-06-04 Thread Robert Wilson
can try to dig up information 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:

RE: Bonding to conductive plastic - best method??

2002-06-04 Thread Robert Wilson
less filler is not only better as a shield, it avoids the shedding of fibers almost completely. Bob Wilson TIR Systems Ltd. Vancouver. -Original Message- From: Chris Wells [mailto:cdwe...@stargate.net] Sent: June 3, 2002 4:20 PM To: Robert Wilson; EMC-PSTC Discussion Group Subject: Re:

RE: Shielded High current cable

2002-06-03 Thread Robert Wilson
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: emc-p...@majordo

RE: Bonding to conductive plastic - best method??

2002-06-03 Thread Robert Wilson
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 unimporta

RE: Bonding to conductive plastic - best method??

2002-06-03 Thread Robert Wilson
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 wi

RE: Conductive Coating

2002-05-29 Thread Robert Wilson
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 curre

RE: English Translation of würfelförmiges

2002-05-28 Thread Robert Wilson
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.

RE: digital devices

2002-05-27 Thread Robert Wilson
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 spe

RE: Coaxial Switches - use with spectrum analyzer and gear?

2002-05-24 Thread Robert Wilson
dant.com] Sent: 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 th

RE: Coaxial Switches - use with spectrum analyzer and gear?

2002-05-23 Thread Robert Wilson
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 D

RE: Emission Standards for Cell Phones and Antennas in Switzerland

2002-05-21 Thread Robert Wilson
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

RE: Some slightly disturbing interview news ...

2002-05-16 Thread Robert Wilson
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: Berk

RE: Constant for Change of Resistance formula.

2002-05-14 Thread Robert Wilson
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 observe

RE: Constant for Change of Resistance formula.

2002-05-13 Thread Robert Wilson
-Original Message- From: Chris 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

RE: Constant for Change of Resistance formula.

2002-05-13 Thread Robert Wilson
red absolute zero" of a material. Try asking a metallurgist? 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

RE: Constant for Change of Resistance formula.

2002-05-10 Thread Robert Wilson
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 factor

RE: A little off topic but ... exploding CD's ???

2002-05-10 Thread Robert Wilson
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: Chri

RE: A little off topic but ... exploding CD's ???

2002-05-10 Thread Robert Wilson
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, a

RE: NEC Wiring Question

2002-05-08 Thread Robert Wilson
You haven't mentioned if they are stranded or not. Assuming they are stranded, then there is no LOGICAL reason why you cannot do this, providing the total wire bundle's combined size does not exceed the AWG range of the terminal. After all, how would the connector "know" which, and how many, strand

RE: stun guns on aircraft

2002-05-07 Thread Robert Wilson
"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

RE: What Every Startup Needs to Know About NEBS

2002-05-07 Thread Robert Wilson
ion. Bob 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 resis

RE: stun guns on aircraft

2002-05-07 Thread Robert Wilson
"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 L

RE: What Every Startup Needs to Know About NEBS

2002-05-07 Thread Robert Wilson
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: Ma

RE: Stun Guns on Aircraft - summary and comments GK

2002-05-06 Thread Robert Wilson
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 num

RE: Stun Guns on Aircraft.

2002-05-03 Thread Robert Wilson
...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, 20

RE: Stun Guns on Aircraft.

2002-05-03 Thread Robert Wilson
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 3

Power Factor regulations.

2002-04-30 Thread Robert Wilson
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 p

RE: General Product Safety Directive - sorry missed something

2002-04-29 Thread Robert Wilson
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

RE: A very nice game

2002-04-24 Thread Robert Wilson
Pegasus 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 li

RE: A very nice game

2002-04-24 Thread Robert Wilson
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 win

RE: A very nice game

2002-04-24 Thread Robert Wilson
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 on this

RE: CE for Fluorescent Lamps

2002-04-24 Thread Robert Wilson
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 emai

RE: A very nice game

2002-04-24 Thread Robert Wilson
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 tha

RE: High Temp Caps and Inductors

2002-04-22 Thread Robert Wilson
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 [mailto:sco...@world.

RE: High Temp Caps and Inductors

2002-04-19 Thread Robert Wilson
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. Mayb

RE: Decoupling - capacitor values

2002-04-18 Thread Robert Wilson
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: richwo...@tyc

RE: Decoupling - capacitor values

2002-04-17 Thread Robert Wilson
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

RE: question on measuring bonding impedance

2002-04-15 Thread Robert Wilson
How about the usual method of determining the value of very low resistances and impedances? Pass a known (relatively high) AC current through the connection, measure the voltage drop and use Ohm's law to calculate the resistance (and this is, after all, an essentially resistive connection). Bob W

RE: EMC & SIX LAYER PCB

2002-04-04 Thread Robert Wilson
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 ag

RE: Danger and Power of Lightning

2002-04-02 Thread Robert Wilson
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 [mailto:geor...@lex

RE: Faying

2002-04-01 Thread Robert Wilson
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. -Origina

RE: Masking - was: chassis bonding - star washers enough?

2002-03-25 Thread Robert Wilson
You are quite right; masking under a screw can create a serious aesthetic problem. It's as mechanical designer, it's something that I whined and complained about often in the past. The best we could do was to minimize its necessity by making metal to metal contact BETWEEN the metal parts being con

RE: chassis bonding - star washers enough?

2002-03-22 Thread Robert Wilson
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 that

RE: SND/ND ratio

2002-03-21 Thread Robert Wilson
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"

RE: Relative merits of various logic families in not generating RFI

2002-03-20 Thread Robert Wilson
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 co

RE: Conductive Coatings/Conductive Plastic

2002-03-19 Thread Robert Wilson
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 wa

RE: product modifications by the end user

2002-03-19 Thread Robert Wilson
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. -Or

RE: IP67 Water Ingress Testing

2002-03-14 Thread Robert Wilson
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

RE: Wire spool labeling requirements

2002-03-13 Thread Robert Wilson
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 me

RE: Don'r Get Caught Running a Red Traffic Light!

2002-03-08 Thread Robert Wilson
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!

RE: EMC and Safety PCB Reviews

2002-03-07 Thread Robert Wilson
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 Safet

RE: EMC and Safety PCB Reviews

2002-03-07 Thread Robert Wilson
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 Wilso

RE: Don't Get Caught Running a Red Traffic Light!

2002-03-07 Thread Robert 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 [mailto:john...@itesafety

RE: Laser Safety

2002-03-06 Thread Robert Wilson
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

RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surface s, chassis, )

2002-03-05 Thread Robert Wilson
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 "lega

RE: Pencil erasers for pre-EMI cleaning? (cleaning mating surfaces, chassis, )

2002-03-01 Thread Robert Wilson
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

RE: Safety Margins based on NSA premises

2002-02-28 Thread Robert Wilson
A 10 dB margin? That's easy for the guy doing the test to say! Heck; why not 20dB?! For the designer who is sweating bullets trying to keep within cost and size requirements, however, this may be quite another matter. Considering the original specifications are somewhat arbitrarily derived in th

RE: Use of PCB Traces as Fuse and Voltage suppressor

2002-02-26 Thread Robert Wilson
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

RE: PCB floating area layout

2002-02-26 Thread Robert Wilson
Sent: 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

RE: PCB floating area layout

2002-02-25 Thread Robert Wilson
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 elect

RE: Potentially Explosive Atmospheres

2002-02-22 Thread Robert Wilson
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 Ltd

RE: South Korean Power System & Schuko Plugs

2002-02-21 Thread Robert Wilson
Message- From: Allen, John [mailto:john.al...@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 up

RE: South Korean Power System

2002-02-20 Thread Robert Wilson
Schuko plugs come in two basic versions. The original (larger) plug has two solid round pins for the AC interconnect, and two metal strips along the side of the plug (one on each side) that are grounding contacts. When inserting the plug, the body of the plug disappears into the socket recess BEFO

RE: South Korean Power System

2002-02-20 Thread Robert Wilson
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. ---

RE: Japan mains voltage

2002-02-20 Thread Robert Wilson
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.

RE: Resistors pulse loading capabilities

2002-02-19 Thread Robert Wilson
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

RE: Chamber Doors

2002-02-19 Thread Robert Wilson
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 ber

RE: [URGENT] Need some information about NEBS..

2002-02-14 Thread Robert Wilson
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 f