---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sat 05/10/14: 5 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:42 AM - Re: When to use Shielded Wire? (Robert L. Nuckolls, III) 2. 09:32 AM - Re: Re: How to lose both ignition systems? (Robert L. Nuckolls, III) 3. 10:03 AM - Re: how to build a 16AWG fuse link (Sacha) 4. 03:36 PM - 43o Card Edge Connector (Sean Stephens) 5. 05:28 PM - Re: 43o Card Edge Connector (Tim Andres) ________________________________ Message 1 _____________________________________ Time: 06:42:10 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: When to use Shielded Wire? At 10:58 PM 5/9/2014, you wrote: I am getting ready to purchase the wire for my project and need to know what wire to purchase. I have read Bob's articles and plan to purchase 18 and 22 gauge wire. I have an EFIS, Garmin 430, PS Engineering Audio Panel, and a KT76 transponder. I will have electronic ignition and LED lights. My question is what wire needs to be shielded and what wire doesn't need shielding? Is it better to just use shielded wire on everything? Seems like extra weight. Is it better to use shielded wire with numerous separate wires inside? or shielded wire with a single wire inside the shielding? Shielding of wires is the weakest of prophylactics against propagation of noise . . . and then effective on a very narrow range of antagonists. If you run two wires side-by-side in the same bundle wherein one wire carries something like millivolt levels of audio from one box to the other (potential victim wire) and the other wire carries some form of electronic violence (potential antagonist wire) then there is a potential for undesirable coupling of energy from the former into the later. Coupling in wire bundles predominates in two forms. Magnetic and electro-static. If the electronic violence is in the form of a high current where the antagonist wire presents a strong local magnetic field, then the effects of that field will be impressed upon the victim wire "longitudinally". The fix for this propagation mode is to break the common longitudinal path (read ground loop) by means of techniques like running potential victim signals on twisted pairs . . .perhaps even transformer coupled at one end. In other words, this propagation mode is best broken by judicious architecture of the victim's i/o ports. If the electronic violence is in the form of high voltage, fast rise-time wave-forms (like magneto p-leads and strobe trigger pulses) then the propagation mode becomes electro-static. The insulation around antagonist and victim wires become 'dielectric' components of a capacitor Albeit a tiny capacitor, effects of the signals on one wire can be impressed on top of the tiny signals in the other. This propagation mode can be broken by shielding one or the other of the two wires. It's best to shield the single antagonist (like the p-lead) so that you don't have to shield a hand-full of potential victims. MIL-STD-704/DO-160 design goals dictate that a product intended for installation on airplanes demonstrate minimum levels of immunity to external stresses along with limits to emitted violence. Products qualified to these design goals are expected to function in communal harmony WITHOUT special attention from the designers or installers of the system. I.e. no automatic inclusion of EXTERNAL prophylactics against propagation of noise. In some few cases (like p-leads and strobe wiring) electronic violence in the wires is a fundamental component of that system's functionality. I.e. it cannot be avoided. Hence, the learned designers and installers of such systems will take judicious steps to contain the noise. I.e. shielded wires and/or p-lead filters installed at the magnetos. Outside these special cases the system integrator. YOU, is held harmless from the need to worry about piling on more prophylactics against noise. The numbers and brutishness of such systems has been declining. "P-leads" from electronic ignitions don't carry magneto-like trash. LED strobes don't utilize fast-rise, HV trigger pulses. Given these advances in system features, I'd venture an assertion that the value of shielding of any wires in an airplane is minimal if not zero. The short answer to you question is: Unless called out on the installation drawings for a device, you don't need to shield the wires. Legacy practices for shielding wires in the communication and navigation systems is a hedge against poor practice in the design or wiring of a potentially antagonistic system that shares the wire bundle. If it's not on the drawing, don't shield it. Bob . . . ________________________________ Message 2 _____________________________________ Time: 09:32:50 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: How to lose both ignition systems? At 12:47 PM 5/9/2014, you wrote: > > >Hello Bob and AEC. >Can we re visit this one. I've read the NTSB accident natative, but >I need a sketch to follow this builders mistake. Bill, I didn't remember that the file-set I posted had a few of holes in it. hit these three links . . . http://tinyurl.com/kyfn4y2 http://tinyurl.com/lmbbrmg and particularly . . . this one http://tinyurl.com/k5593wo Bob . . . ________________________________ Message 3 _____________________________________ Time: 10:03:00 AM PST US Subject: Re: AeroElectric-List: how to build a 16AWG fuse link From: Sacha Ok in that case I have all I need. Thank you. Sacha Do not archive. > On May 10, 2014, at 2:04, "Robert L. Nuckolls, III" wrote: > > A 30A fuse of any style would be find. ________________________________ Message 4 _____________________________________ Time: 03:36:57 PM PST US From: Sean Stephens Subject: AeroElectric-List: 43o Card Edge Connector I'm looking for help on what orientation the card edge connector used for shield termination on the back of a Garmin 430 should be inserted. It's a Garmin 336-00029-00 or AMP 583853-4 card edge connector. It has a "spring" side and a "barb" side. Not sure what to actually call them and that's the best I can do. :) Should the "barb" side face in, up, out or down in relation to the termination block when inserting on the back of the 430? Thanks, -Sean ________________________________ Message 5 _____________________________________ Time: 05:28:21 PM PST US Subject: Re: AeroElectric-List: 43o Card Edge Connector From: Tim Andres Can't answer your question, but FWIW, I don't use it. I really like Bob's avionics ground bus, I use one mounted close to the back of the radio stack. Tim > On May 10, 2014, at 3:35 PM, Sean Stephens wrote: > > > I'm looking for help on what orientation the card edge connector used for shield termination on the back of a Garmin 430 should be inserted. > > It's a Garmin 336-00029-00 or AMP 583853-4 card edge connector. It has a "spring" side and a "barb" side. Not sure what to actually call them and that's the best I can do. :) > > Should the "barb" side face in, up, out or down in relation to the termination block when inserting on the back of the 430? > > Thanks, > > -Sean > > > > ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.