At 00:58 -0400 5/14/10, Richard Gerome wrote, and I snipped: > but do not fold up the display screen cord for this may cause a inductive > voltage problem and mess up the picture (this happens when guys with the hot > rods get engines and the computer and wire harness out of junk yards and the > wire harness is too long so they would roll up the wire harness and wire tie > it together, then the engine would run really bad and they wouldn't know why) > with all those wires running through it and all the different voltages cause > it to act like an ignition coil and increase the voltage... Some of you > probably wont know what I'm talking about here but for those of you who do > know, "great"!!! Just thought I would add this comment because I see so many > people with this mess behind their computer desk... Maybe this could be some > of the mysteries for some of the problems with computers messing up??? Sorry > if this is off topic, needed to be told...
I agree that it needs to be told. There are two different reasons for not twisting up cables. Coaxial cable with a single center conductor carefully kept at the middle of a cylindrical outer shield is used for radio frequency data. If you bend it sharply and hold it that way the center conductor migrates through the polyethylene insulation until it's not centered. That makes for reflections of the electrical signals at the bend and, even worse, can actually short the center conductor to the shield. Good old RG58 and RG59 coax at about 1/4 inch diameter is rated for bend radius no smaller than 2 inches. Video cables use smaller coax but one still has to be careful. Twisted pair cables are not so dependent on positioning of the conductors but they are very dependent on matching of the insulation thickness and the twist rate of the conductors. If either gets changed by tight bending of the cable reflection points are created. When reflected energy gets re-reflected the result is a delay which can interfere with some other data bit because of the speed of light in the cable. Those CAT-5 ethernet cables depend on different twist rates for each pair to minimize magnetic crosstalk between pairs. Running two unshielded CAT-5 cables close to each other is asking for trouble. It all depends on cable length and the data rate. A number worth remembering is that the speed of light in vacuum is about one US foot per nanosecond. For a ten foot cable and a data rate of 100 MHz bit number two arrives at the end about the same time as bit number three is transmitted. As data rates get faster - as with USB yet to be - cable cleanness becomes more and more important. -- --> Marriage and kilo are troubled words. Turmoil results when centuries-old usage is altered in specialized jargon <--. -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to g3-5-list@googlegroups.com For more options, visit this group at http://groups.google.com/group/g3-5-list
