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"John Woodgate" wrote in message ... I read in sci.electronics.design that CW wrote (in ) about 'Cellphones and Bombs', on Thu, 18 Mar 2004: You can try to ratioanlize it as much as you want. The willfull electronic interference of a radio service is a crime. Did you read the part of my post about signal blocking? I thought not. Go back and try again. If a terorist is going to strike, he is going to strike. The Department of Homeland Paranoia is not going to be able to do anything about it. I am ALMOST old enough to remember a similar idea held in UK and Europe before WW2, that 'the bomber (aircraft) will always get through'. The RAF pretty well disproved it. OTOH, the Eighth Air Force did pretty much prove it. Unfortunately, they didn't always come back. Ed wb6wsn |
"Roger Gt" wrote in message om... "Active8" wrote : Roger Gt wrote: : "Paul Burridge" wrote : : Jim Thompson wrote: : : : :I was struck by a thought when I heard the latest Palestinian : :terrorist trick is to send a kid through the border with a : back-pack : :bomb triggered by a cell phone.... : : : :The Israelis should get a telemarketer's speed dialer and : constantly : :dial away... boom... boom... boom... : : : :ROTFLMAO! : : : : Yes, I'm rolling on the floor laughing at all these deaths, too, : as : : I'm sure we all are. : : Huh? : He seemed to be laughing at the lame Idea! I also thought it : funny that anyone would try something which would almost totally : wipe out the cellular phone service for the entire country... : : does a 200 station phone room with auto-dialers all calling one : state wipe out POTs? WTH are *you* talking about? Gee - Primitive! Not a Telephone guy I guess...... The last autodialer I worked on was a Dual DS3 line unit with a router. 2 times 864 lines wide. A few of those would really choke a network! So YOU are one of the SOB's who create those things? Ed wb6wsn |
"Ben Bradley" wrote in message ... In rec.radio.amateur.antenna, ( I suppose this is on RRAA because cell phones have antennas ) sci.electronics.design,sci.electronics.basics, Jim Thompson wrote: Of course, in the USA, one could put the cell number on the national DO-NOT-CALL list, then only an "illegal" telemarketer would trigger the bomb. Bombers might figure ways around this (especially if they search Usenet), such as a cellphone answering circuit and a "dee tee em eff" decoding circuit. I wouldn't want to spell it out for them... ...Jim Thompson They may not be as illiterate as you suggest; perhaps Pig Latin could offer sufficient encryption: Eeday eetay emyay effyay. Ed wb6wsn |
See my post titled Intrinsic Safety -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/ |
John Michael Williams says... Actually, a former maritime safety engineer Emailed me about this. However, he could not locate the law or regulation which defines "intrinsic safety". If you can find a law or regulation governing operation of a transmitter around a gas pump, please post it. The National Fire Protection Association’s (NFPA) National Electrical Code (Article 500, NFPA 70) defines Hazardous Locations as those areas "where fire or explosion hazards may exist due to flammable gases or vapors, flammable liquids, combustible dust, or ignitable fibers or flyings." NFPA-NEC Intrinsic Safety ratings detail the specific Hazardous Location in which an electrical device can be used without fear of electrostatic discharge that may cause an explosion. The classification that applies to auto fuels a Class I: Gases, vapors and liquids - Group D: Hydrocarbons, fuels, solvents, etc. - Division II: Not normally present in explosive concentrations (but may accidentally exist). Other standards that apply to Intrinsic Safety a ANSI/UL 913 Intrinsically Safe Apparatus and Associated Apparatus for Use in Class I, II, and III, Division 1, Hazardous (Classified) Locations US Mine Safety and Health Administration (MSHA) Mine Wide Monitoring Systems (MWMS) Program: MSHA ACRI2001 - 30 CFR Part 18, Part 23 CENELEC/EN European Standards for electrical apparatus for potential explosive atmosphere General requirements EN 500 14 [IEC 60079-0] Increased safety "e" EN 500 19 Intrinsic safety "i" EN 500 20 [IEC 60079-11] [BS 5501 part 7] Canadian Standards Association (CSA) C22.2 No. 157-92 ANSI/ISA RP 12.6 Wiring Practices for Hazardous (Classified) Locations Instrumentation - Part 1: Intrinsic Safety Factory Mutual Research Corporation (FMRC)? American Society for Testing and Materials (ASTM)? Also see: http://www.crouse-hinds.com/CrouseHi...afe/insafe.cfm http://www.ascojoucomatic.com/images...f1/V1005gb.pdf http://www.mtlnh.com/datashts/sensors/Sen%20Specs.pdf http://www.msha.gov/S&HINFO/TECHRPT/...ICAL/imisf.pdf http://www.gexcon.com/index.php?src=...HBcontents.htm http://www.electrona.se/pdf/tp_1110_3.pdf http://www.ieee-pcic.org/archive/pcic98.pdf -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/ |
Jan Panteltje says... it rang, and that is how they found it. So it MUST have had a sim card. My cellphone rings without any simm card. All I have to do is to set the alarm clock function. -- Guy Macon, Electronics Engineer & Project Manager for hire. Remember Doc Brown from the _Back to the Future_ movies? Do you have an "impossible" engineering project that only someone like Doc Brown can solve? My resume is at http://www.guymacon.com/ |
I read in sci.electronics.design that Ed Price wrote
(in 12W6c.19644$uh.12711@fed1read02) about 'Cellphones and Bombs', on Sat, 20 Mar 2004: "John Woodgate" wrote in message ... I read in sci.electronics.design that CW wrote (in ) about 'Cellphones and Bombs', on Thu, 18 Mar 2004: You can try to ratioanlize it as much as you want. The willfull electronic interference of a radio service is a crime. Did you read the part of my post about signal blocking? I thought not. Go back and try again. If a terorist is going to strike, he is going to strike. The Department of Homeland Paranoia is not going to be able to do anything about it. I am ALMOST old enough to remember a similar idea held in UK and Europe before WW2, that 'the bomber (aircraft) will always get through'. The RAF pretty well disproved it. OTOH, the Eighth Air Force did pretty much prove it. Unfortunately, they didn't always come back. The idea was that there was *no effective defence** against bomber aircraft, and it is that which is false. OTOH, there was no effective defence against V2 rockets at the time. Luckily, they were developed too late to prevail. -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk |
Guy Macon http://www.guymacon.com wrote in message ...
Jan Panteltje says... My cellphone rings without any simm card. All I have to do is to set the alarm clock function. Yes, that works here too. Even when the thing is off! But what I ment is that I got the impresion it was really ringing, like they dialed it, and for that you need a SIM. Of cause if you had the phone, a look in the flash would reveal much of what they had done (likely some card was in it for testing). Probably we will not hear details for obvious reasons. But again, do not blame it on cellphones, if these were not available they would use something else I am sure. In fact the phone gave them away! We will have to live with the danger. I missed an IRA bomb by one minute years ago in London, just clearly remember the thought 'shall I go have a cup of coffee in that Wimpy (coffee bar), or go back to the office (tube across it)'. We had to go for a production to Italy next day or so, and had a lot to do (was working in London in that time). So I took the tube back to the office, whan I arrived there it was on the news that a IRA bomb was in that coffee shop. So, dangers surround us all the time, why we move, and how we move, our timing, be concious. JP |
On 17 Mar 2004 12:02:15 -0800, (John Michael
Williams) wrote: However, the first radios transmitted sparks, so in principle it should be possible to transmit near a long wire separated by a small gap from ground or another wire and get a small spark. There were few spark transmitters mounted in automobiles. They were just too inefficient, big, and clumsy to be functional. Transmitters in vehicles really didn't start until tube type transmitters became popular. The problem was that the typical mobile radio used a dynamotor (motor-generator) combination to generate the necessary high voltages. With the radio and dynamotor mounted in the trunk of the vehicle, there was a good chance that gasoline fumes would accumulate in the trunk of the vehicle and be ignited by the spark from the dynamotor commutator. See the photo of the 80D at: http://www.telmore.com/ka1nvz/old_tw...ola/49-59.html The dynamotor is the black cylinder near the handle. The 140D was twice as big and heavy. Back in the 1960's, my 1960 Ford Falcon had an assortment of Motorola 80D and 140D radios in the trunk. I experienced a small explosion in the trunk ignited by the dynamotor. I had filled up the gas tank at the local gas stop (for 19 cents per gallon). Warm weather caused it to expand and leak vapour into the trunk. Key the transmitter, the dynamotor starts, sparks, and boom. I then attached a 1.2 m monopole antenna to an oscilloscope. This antenna has a Schottky hot carrier diode and impedance matching resistors builtin. Lovely. A harmonic generator. Any reason you want lots of harmonics? Shottky diodes or any other non-linear device, do not belong in antenna matching circuits. It's home made, but it's probably as good as any other wire about that long. Wrong. Optimum for CB is either a 1/4 wave monopole (102 inches) or two of them to form a half wave dipole. So, first conclusion: To get even a 1 V spark would take a wire at least 9 m long, all somehow kept within 1 m of the transmitter. Thus, it appears it is not feasible to create a hazardous spark with a CB at a gas station. Find a 4 watt flourescent light. Attach a 1/4 wave antenna to your 5 watt CB radio. Transmit. Hold lamp in hand and touch the end of the 102" antenna. It will light when you talk. (Note: With AM modulation, you only get 5 watts when you yell into the microphone. Without modulation, you only get about 2.5 watts of RF). Now, ask yourself what voltage is required to light the flourescent lamp. In order to get a spark, you need to generate enough voltage to ionize the air between the contacts. That's about 20KV/inch. If we eliminate the antenna, 5 watts of RF into 50 ohms will generate: P = E^2 / R E = 16v rms E(peak) = 1.4 * 16 = 22 volts The gap necessary to create an arc with 22 volts is: 22V / 20,000V/in = 0.001 inches Kinda small, but given a microscope, a 1 mil spark gap will arc. Of course the VSWR protection circuity in the transmitter will instantly shut down the transmitter when it arcs, but that takes a few millisec. Notice that this is a voltage phenomenon, and is not dependent upon the power level. Therefore, an antenna that offers a voltage step-up will generate a higher voltage. However as the antenna is in the air and nowhere near a close enough ground to arc, it doesn't matter. If there's gonna be any arcing, it will be between the xmitter output and the base of the antenna. The typical mobile FM transmitter of the day (1960's) cranked out between 15 and 150 watts. Most were around 75 watts. Run the calcs again for 75 watts and see if the gap is more reasonable (I'm lazy). The next question is how much heat is necessary from the arc to ignite the gasoline vapour. I'll leave that as an exercise for when I have more time to burn. Gotta get back to lying and cheating on my taxes. -- # Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060 # 831.336.2558 voice http://www.LearnByDestroying.com # # 831.421.6491 digital_pager AE6KS |
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