RE: 2. 4 GHz cordless telephone, question of general interest
22 GHz is the resonant frequency of water folks. Not 2.45 GHz. uwave ovens heat by way of dielectric heating. Oils heat much faster than water. That's why your uwave food mfrs load up on the oils and salts in the food. Which by the way, hasn't been looked into as far as a high fat diet contributing to cancer. Or has it? Also, the higher above 1GHz you go, the more surface heating of a human body happens. Not deeper. Deep tissue heating combined with surface tissue heating happens below that. Ionization of atoms and molecules require much higher freqs which translates to higher levels of eVs. Typical eV's that occur during normal chemical reactions with STP (standard temp and pressure) is about 15 eV. The photo-electric work function of say Tungsten = 4.58 eV = 2694 Angstroms = 0.27 cm. Pretty damn small in my opinion. And you have to get far above approx 10 mW/cm^2 to really start being a problem. 1 mW/cm^2 I think is the limit. I worked the numbers out with one uwave oven which I thought had exceedingly high emissions, and it turned out to be pretty benign in terms of W/cm^2. More like uW/cm^2. Higher freqs are required to actually start perturbation at the atomic level. At the low GHz range, you're only perturbing the general molcular structure en masse. You have to go much higher to start doing the funky thing with an atom. Trying to consider that *only* uwave ovens are even involved with the whole cancer thing leaves out many many other factors to the point of being ignored. All the above of course, IMHO. And opinions may vary at any speed. Regards, Doug McKean > -Original Message- > From: owner-emc-p...@ieee.org [mailto:owner-emc-p...@ieee.org]On Behalf > Of Ken Javor > Sent: Friday, April 20, 2001 2:40 PM > To: emc-p...@ieee.org > Subject: 2. 4 GHz cordless telephone, question of general interest > > > > Someone on this forum likely knows the answer to this question... > > I was at Wal-Mart the other day and they had 2.4 GHz cordless phones on > clearance. My home cordless phones are 900 MHz. One is multiple > channels, > the other is some kind of spread spectrum. 2.4 GHz is very close to 2450 > MHz, the microwave oven frequency that resonates with H2O > molecules. Is 2.4 > GHz close enough to 2450 MHz to cause significantly more heating than 900 > MHz (in the human head adjacent to the head/handset antenna)? I realize > this is very low power relative to a cell phone, but I wonder if the issue > was ever addressed. Another way of asking this question is, what > is the "Q" > of H20 resonance? If it is much better than 50, the problem is not > important. If it is 50 or less, then 2.4 GHz would transfer more > energy to > head tissue than 900 MHz. One way of measuring this effect would > be to time > how long it takes to raise the temperature of a beaker of water a > set amount > at 2450 MHz, and then time how long it takes at 2400 MHz... > > But this all must have been done already... > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
RE: Job Description
Oh, something like This person SHALL 1. Address any compliance/agency issues during the entire life cycle of a product starting with product development, maintanence of approvals through product release, and finally with product obsolescence. 2. This will require someone to be proactive in both design and manfacturing phases of a product. 3. Perform any prelimenary testing where possible. 4. Manage product compliance testing with the appropriate test labs and agencies. 5. Maintain all documents of product approval. 6. Manage sustaining compliance issues during the life cycle of a product after manufacturing release. 7. Be involved in the ECR/ECO process where changes could compromise agnecy approvals of products. 8. Will expected to work either independently or within groups. 9. Must have a working knowledge of the following: the pertinent standards to which the product is being tested, EMC to include printed circuit board design techniques, safety issues to include any possible liability issues with said product, any possible National Electrical Codes within said country, bills of materials, ECR/ECO processes used by this or any other company with which this companies does OEM arrangements. 10. BS expected. MS preferrred. PE desired. (any state license is sufficient but all of them is desired ...) 11. Multi-lingual in at least 5 languages. 12. Be able to correct hardware design in a blink. 13. Have enough brass to call a "stop ship" at any time. 13. And then once hired, expect to be generally ignored ... 14. Must be willing to work lots of overtime without being asked. 15. Pay approx $35K max ... Regards, Doug McKean --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
Hi Glyn, Here is one way to approach 30kV. First, slide out of your car seat, the Ford Taurus is great for this effect. This puts a charge on your behind. As you get out of the car (everything is plastic so you remain charged with respect to the car) your voltage rises because Q=CV. Q stays the same (charge on your behind) but since C to the car goes down, voltage goes up. Then you go to close the metal door and a huge spark jumps between your hand and the door. Usually this results in jumping into the air muttering a few four letter words sometimes ending in (I am sure this happens with other cars, I just happen to own Fords, which I like) "F O R D". I wonder why the car companies don't make seat material out of anti-static material BTW, contact discharge has the same risetime at all reasonable voltages, as opposed to air discharges, but still some equipment will fail at a low voltage and pass at high voltages. I can imagine a few ways circuits might do this. The effect is more pronunced with air discharge because of the risetime dependence on voltage (really arc length and whatever effects that, including speed of approach). Doug "Glyn Garside(TUV)" wrote: > > >>On the other hand very low voltage (and energy) events, such as jingling > >>change have very high di/dt because of the tens of ps risetimes that > >>occur at low voltage. > > I think this is why, as I recall, some (maybe all?) IEC standards require > you to test not only to the ESD level indicated, but also the lower levels > too. For example, if you are required to test at level 4, you are also > required test at levels 3, 2 and 1. This is counter-intuitive -- "Surely > the highest voltage is the worst case?" -- but apparently grounded in good > physics, which Doug explains better than I would. > > PS: As to testing at higher levels than typical IEC values, I have read > that the human body can, rarely, gain a charge of up to about 30kV(??), in > conditions of low RH. Others may have better insight into this. Also, some > manufacturers may want to build some "margin" into their test results: if > five samples pass at 8kV, how sure can you be that the next 995 production > units would also pass? > > PPS: I have a question of my own, drifting off topic slightly: if the > relative humidity was fairly high when you passed the ESD test, and you > retest (esp. air discharge?, or indirect discharge?) some months later when > humidity is lower, could the same EUT now fail? (I think the answer is, > yes?) > > Best Regards, Glyn > > Glyn R. Garside (mailto:ggars...@us.tuv.com) > Senior Engineer, Industrial Machinery Division > TUV Rheinland of North America, Inc. (Chicago Office) > 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA > http://www.us.tuv.com > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," -- --- ___ _ Doug Smith \ / ) P.O. Box 1457 = Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-( ) | o |Email: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
Re: 2. 4 GHz cordless telephone, question of general interest
Two points regarding this question. I understand that 2.4 GHz is not a resonant frequency of the water molecule which resonates at a much higher frequency. 2.4 GHz is just the ISM frequency. Also the depth of penetration is only a few cm at 2.4 GHz and is somewhat higher at 900 MHz. 27 MHz diathermy gives a very good depth of penetration and more even heating through human joints. Regards John Cronin >From: "Ralph Cameron" >Reply-To: "Ralph Cameron" >To: "Ken Javor" , >Subject: Re: 2. 4 GHz cordless telephone, question of general interest >Date: Fri, 20 Apr 2001 22:39:29 -0400 > > >In terms of heating ( cooking ) 900Mhz is more efficient but its a question >then of density of tissue , I understand that between 70-90Mhz the human >body absorbs most energy and that first microwave ovens were designed around >450Mhz but 2.4 Ghz was an I.S.M. band so permitted limitless power. > >The leakage in the average Microwave oven should be so small that you'd >never hear it on a 2.4Ghz cell phone (i.e. 50Mhz off frequency) > >many offie type 2.4Ghz cordless phone use 900mw on the base unit and 200mw >on the handset. I would suspect the field intensity that close to the head >could be substantial. > >Ralph Cameron > >- Original Message - >From: "Ken Javor" >To: >Sent: Friday, April 20, 2001 5:40 PM >Subject: 2. 4 GHz cordless telephone, question of general interest > > > > > > Someone on this forum likely knows the answer to this question... > > > > I was at Wal-Mart the other day and they had 2.4 GHz cordless phones on > > clearance. My home cordless phones are 900 MHz. One is multiple >channels, > > the other is some kind of spread spectrum. 2.4 GHz is very close to 2450 > > MHz, the microwave oven frequency that resonates with H2O molecules. Is >2.4 > > GHz close enough to 2450 MHz to cause significantly more heating than 900 > > MHz (in the human head adjacent to the head/handset antenna)? I realize > > this is very low power relative to a cell phone, but I wonder if the issue > > was ever addressed. Another way of asking this question is, what is the >"Q" > > of H20 resonance? If it is much better than 50, the problem is not > > important. If it is 50 or less, then 2.4 GHz would transfer more energy >to > > head tissue than 900 MHz. One way of measuring this effect would be to >time > > how long it takes to raise the temperature of a beaker of water a set >amount > > at 2450 MHz, and then time how long it takes at 2400 MHz... > > > > But this all must have been done already... > > > > --- > > This message is from the IEEE EMC Society Product Safety > > Technical Committee emc-pstc discussion list. > > > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > > > To cancel your subscription, send mail to: > > majord...@ieee.org > > with the single line: > > unsubscribe emc-pstc > > > > For help, send mail to the list administrators: > > Michael Garretson: pstc_ad...@garretson.org > > Dave Heald davehe...@mediaone.net > > > > For policy questions, send mail to: > > Richard Nute: ri...@ieee.org > > Jim Bacher: j.bac...@ieee.org > > > > All emc-pstc postings are archived and searchable on the web at: > > http://www.rcic.com/ click on "Virtual Conference Hall," > > > > > > >--- >This message is from the IEEE EMC Society Product Safety >Technical Committee emc-pstc discussion list. > >Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > >To cancel your subscription, send mail to: > majord...@ieee.org >with the single line: > unsubscribe emc-pstc > >For help, send mail to the list administrators: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > >For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > >All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
Job Description
Dear Colleagues, I have been asked to write a complete new job description for a Product Safety / Codes Compliance Engineer. Although being familiar with this activity (I'm on it for almost 10 years), I would like to avoid describing "my job", since this could lead to some kind of bias. If any of you has a job description of a product safety engineer who is responsible for getting compliance certifications of electrical products, I would be very thankful for receiving it. In order to avoid overflowing this list with attached files, I'd appreciate receiving the responses through my personal email address. Regards, Luiz --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
>>On the other hand very low voltage (and energy) events, such as jingling >>change have very high di/dt because of the tens of ps risetimes that >>occur at low voltage. I think this is why, as I recall, some (maybe all?) IEC standards require you to test not only to the ESD level indicated, but also the lower levels too. For example, if you are required to test at level 4, you are also required test at levels 3, 2 and 1. This is counter-intuitive -- "Surely the highest voltage is the worst case?" -- but apparently grounded in good physics, which Doug explains better than I would. PS: As to testing at higher levels than typical IEC values, I have read that the human body can, rarely, gain a charge of up to about 30kV(??), in conditions of low RH. Others may have better insight into this. Also, some manufacturers may want to build some "margin" into their test results: if five samples pass at 8kV, how sure can you be that the next 995 production units would also pass? PPS: I have a question of my own, drifting off topic slightly: if the relative humidity was fairly high when you passed the ESD test, and you retest (esp. air discharge?, or indirect discharge?) some months later when humidity is lower, could the same EUT now fail? (I think the answer is, yes?) Best Regards, Glyn Glyn R. Garside (mailto:ggars...@us.tuv.com) Senior Engineer, Industrial Machinery Division TUV Rheinland of North America, Inc. (Chicago Office) 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA http://www.us.tuv.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
Re: 2. 4 GHz cordless telephone, question of general interest
In terms of heating ( cooking ) 900Mhz is more efficient but its a question then of density of tissue , I understand that between 70-90Mhz the human body absorbs most energy and that first microwave ovens were designed around 450Mhz but 2.4 Ghz was an I.S.M. band so permitted limitless power. The leakage in the average Microwave oven should be so small that you'd never hear it on a 2.4Ghz cell phone (i.e. 50Mhz off frequency) many offie type 2.4Ghz cordless phone use 900mw on the base unit and 200mw on the handset. I would suspect the field intensity that close to the head could be substantial. Ralph Cameron - Original Message - From: "Ken Javor" To: Sent: Friday, April 20, 2001 5:40 PM Subject: 2. 4 GHz cordless telephone, question of general interest > > Someone on this forum likely knows the answer to this question... > > I was at Wal-Mart the other day and they had 2.4 GHz cordless phones on > clearance. My home cordless phones are 900 MHz. One is multiple channels, > the other is some kind of spread spectrum. 2.4 GHz is very close to 2450 > MHz, the microwave oven frequency that resonates with H2O molecules. Is 2.4 > GHz close enough to 2450 MHz to cause significantly more heating than 900 > MHz (in the human head adjacent to the head/handset antenna)? I realize > this is very low power relative to a cell phone, but I wonder if the issue > was ever addressed. Another way of asking this question is, what is the "Q" > of H20 resonance? If it is much better than 50, the problem is not > important. If it is 50 or less, then 2.4 GHz would transfer more energy to > head tissue than 900 MHz. One way of measuring this effect would be to time > how long it takes to raise the temperature of a beaker of water a set amount > at 2450 MHz, and then time how long it takes at 2400 MHz... > > But this all must have been done already... > > --- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://www.rcic.com/ click on "Virtual Conference Hall," > > --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://www.rcic.com/ click on "Virtual Conference Hall,"
