Path: utzoo!telecom-request Date: Fri, 17 May 91 12:08:00 CDT From: "Patton M. Turner" Newsgroups: comp.dcom.telecom Subject: Re: Cellular Phone Use in Aircraft Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 368, Message 1 of 7 Lines: 33 > In all seriousness: can a cellphone trigger explosives? It > seems that a radiodetonator would need to be very selective about what > signals trigger it. Under proper conditions, blasting caps can be set off by an RF field. A few years ago, while installing a fiber link between two CO's near here I had some caps left over after we blasted a trench through rock on a section of highway right-of-way. Being the curious sort, I decided to see if I could set a cap off with a CB or VHF radio. I cut one leg of the wire to a resonant length (about 50 feet, slightly higher for the CB), and grounded the other leg to a ground rod. Using a 2 meter amateur transmitter feeding 150 watts in to a 5/8 wave (3db gain) antenna, the cap exploded from a distance of 20 feet (this was probably overkill). The CB did not set the cap off at a distance of 7 feet. Note: I buried the cap in the ground, I'm not stupid. There are several reason that caps are almost never set off accidentally. First, lead wires are NEVER allowed to be grounded, and splices are not even allowed to touch the ground. Secondly, the shooting line (wire from caps to blasting machine) is twisted together to prevent an induced potential between the wires. Finally, the end of the shooting line is shunted until it is attached to the blasting machine, then the blasting machine will shunt the line until the fire switches are depressed. In conclusion, I believe it would be virtually impossable to detonate a blasting cap with a cell phone. But just to be safe ... Pat Turner KB4GRZ internet: pturner@eng.auburn.edu