---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 10/28/03: 33 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:13 AM - Re: external power jack and crowbar OV module (Jim Jewell) 2. 01:01 AM - Re: external power jack and crowbar OV module (Werner Schneider) 3. 05:02 AM - Re: google conversion tool (CBFLESHREN@aol.com) 4. 05:30 AM - Re: external power jack and crowbar OV (Robert L. Nuckolls, III) 5. 05:42 AM - Re: Current Limiters (Robert L. Nuckolls, III) 6. 05:56 AM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III) 7. 07:33 AM - Alt Field question (Scott Bilinski) 8. 07:52 AM - Fastons (Eric M. Jones) 9. 07:57 AM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III) 10. 07:59 AM - Re: Current Limiters (Robert L. Nuckolls, III) 11. 10:00 AM - Re: BUS / Fuse Blocks (Rick Caldwell) 12. 10:17 AM - Re: BUS / Fuse Blocks () 13. 11:46 AM - Re: wiring Nova and Aeroflash strobe/nav/pos lights (Joa Harrison) 14. 12:00 PM - Aircraft Configuration Spreadsheet (Pete Waters) 15. 12:44 PM - landing/taxi lights (Carlos Sa) 16. 02:56 PM - Re: landing/taxi lights (Matt Prather) 17. 02:58 PM - Inductive current measuring device .... (Jim Sower) 18. 03:14 PM - Re: landing/taxi lights (Carlos Sa) 19. 03:46 PM - Run away alternator scenario (BAKEROCB@aol.com) 20. 04:27 PM - Inductive current measuring device .... (Eric M. Jones) 21. 04:52 PM - Re: Current Limiters (Ernest Kells) 22. 05:00 PM - Re: Ground Loop (MikeM) 23. 05:03 PM - coax terminations and grounding a pusher (Alex Balic) 24. 05:59 PM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III) 25. 06:04 PM - Re: coax terminations and grounding a pusher (Robert L. Nuckolls, III) 26. 06:06 PM - AMP / Cannon Connectors (David Schaefer) 27. 06:15 PM - Re: Current Limiters (Robert L. Nuckolls, III) 28. 06:23 PM - Fw: Reply from Nova Re: Installation Diagrams (Robert L. Nuckolls, III) 29. 06:32 PM - Re: Current Limiters (Matt Prather) 30. 07:12 PM - Re: Aircraft Configuration Spreadsheet (George) 31. 07:53 PM - Re: Run away alternator scenario (Robert L. Nuckolls, III) 32. 09:16 PM - Re: Fw: Reply from Nova Re: Installation Diagrams (Joa Harrison) 33. 09:35 PM - Fuse Holders (Kingsley Hurst) ________________________________ Message 1 _____________________________________ Time: 12:13:29 AM PST US From: "Jim Jewell" Subject: Re: AeroElectric-List: external power jack and crowbar OV module --> AeroElectric-List message posted by: "Jim Jewell" Hi Werner, Since the people at B&C changed their site layout things are hard to find, go to http://www.bandcspecialty.com/cgi-bin/ez-catalog/cat_display.cgi?26X358218 Scroll down the page about 3/4 and you will find what you are seeking. Try putting a solar cell type charger on your battery, it should help some. Lots of luck, Jim in Kelowna ----- Original Message ----- From: "Werner Schneider" Subject: AeroElectric-List: external power jack and crowbar OV module > --> AeroElectric-List message posted by: "Werner Schneider" > > Can somebody please help me. > > During this very cold time in Switzerland I get troubles with my 17Ah > Panasonic, if the engine starts not at the first time, or if the plane sits > for several weeks. So I'm going to fit the Piper/Cole Hersee connector. > > I've searched yesterday through the Bob's site as well as the B and C site > but could not find the crowbar OV module as a part. > > Is this module not available as a part, or did I just miss it? > > Many thanks for pinpointing > > Werner > > ________________________________ Message 2 _____________________________________ Time: 01:01:32 AM PST US From: "Werner Schneider" Subject: Re: AeroElectric-List: external power jack and crowbar OV module --> AeroElectric-List message posted by: "Werner Schneider" Hello Jim, thanks for the help, exactly what I've searched for, I did search everywhere (would have expected to see it close to the regulators) but have overseen it in the MISC section. A sercah function would help a lot. I've copied todd to let him know. Many thanks Werner ----- Original Message ----- From: "Jim Jewell" Subject: Re: AeroElectric-List: external power jack and crowbar OV module > --> AeroElectric-List message posted by: "Jim Jewell" > > Hi Werner, > > Since the people at B&C changed their site layout things are hard to find, > go to > http://www.bandcspecialty.com/cgi-bin/ez-catalog/cat_display.cgi?26X358218 > Scroll down the page about 3/4 and you will find what you are seeking. > Try putting a solar cell type charger on your battery, it should help some. > > Lots of luck, > > Jim in Kelowna > > > ----- Original Message ----- > From: "Werner Schneider" > To: > Subject: AeroElectric-List: external power jack and crowbar OV module > > > > --> AeroElectric-List message posted by: "Werner Schneider" > > > > > Can somebody please help me. > > > > During this very cold time in Switzerland I get troubles with my 17Ah > > Panasonic, if the engine starts not at the first time, or if the plane > sits > > for several weeks. So I'm going to fit the Piper/Cole Hersee connector. > > > > I've searched yesterday through the Bob's site as well as the B and C site > > but could not find the crowbar OV module as a part. > > > > Is this module not available as a part, or did I just miss it? > > > > Many thanks for pinpointing > > > > Werner > > > > > > ________________________________ Message 3 _____________________________________ Time: 05:02:25 AM PST US From: CBFLESHREN@aol.com Subject: Re: AeroElectric-List: google conversion tool --> AeroElectric-List message posted by: CBFLESHREN@aol.com < Some of you probably already know this but Google has a feature for doing unit conversions that is *very* slick. Highly case and syntax insensitive so it's easy to use. Check it out. http://www.google.com/help/features.html#calculator And for those that have not heard of this great FREE Conversion Download see this, less than 5 kilobyte jewel: http://www.joshmadison.com/software/convert/dl.asp Chris Fleshren ________________________________ Message 4 _____________________________________ Time: 05:30:59 AM PST US From: "Robert L. Nuckolls, III" module Subject: Re: AeroElectric-List: external power jack and crowbar OV module --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" module At 07:40 AM 10/28/2003 +0100, you wrote: >--> AeroElectric-List message posted by: "Werner Schneider" > > >Can somebody please help me. > >During this very cold time in Switzerland I get troubles with my 17Ah >Panasonic, if the engine starts not at the first time, or if the plane sits >for several weeks. So I'm going to fit the Piper/Cole Hersee connector. > >I've searched yesterday through the Bob's site as well as the B and C site >but could not find the crowbar OV module as a part. > >Is this module not available as a part, or did I just miss it? > >Many thanks for pinpointing It's 3/4 of the way down the page at http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?26X358218 Bob . . . ________________________________ Message 5 _____________________________________ Time: 05:42:18 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Current Limiters --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 05:13 PM 10/27/2003 -0500, you wrote: >--> AeroElectric-List message posted by: "Ernest Kells" > > >I have a large capacity Precision alternator (installed) that I would like >to limit for a basic VFR-only RV-9A. > >I have installed the Vans 40 amp shunt. I notice that the smallest current >limiter in the B&C catalogue is also 40 amps (C905-40). I was looking for >about 35 amps so as to not having any nuisance problems. > >Is this a problem? I don't want to risk blowing the Vans 40 amp shunt. The >extra amps would be a nice cushion for the seat heaters and that initial >load on the pitot tube heater. > >This seems safe - but I want to be certain. Thanks for any help. The shut's rating has more to do with calibration than with maximum allowable current limits. The ANL "limiters" are just really robust fuses and you use them to protect wires from hard faults. In this case, shorted diodes in the alternator are highest risk (although quite small with modern alternators) fault potential. The selection of a limiter has almost no relationship with the size of you ammeter shunt and no relationship for "protecting" it. What is the capacity of your alternator? You cited "large capacity" but with no number to tell us what "large capacity" means. Bob . . . ________________________________ Message 6 _____________________________________ Time: 05:56:43 AM PST US From: "Robert L. Nuckolls, III" strobe/nav/pos lights Subject: Re: AeroElectric-List: wiring Nova and Aeroflash strobe/nav/pos lights --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" strobe/nav/pos lights At 01:54 PM 10/27/2003 -0800, you wrote: >--> AeroElectric-List message posted by: Joa Harrison > > > >I seem to recall a schematic for cleanly (noise wise) wiring the Nova >supplies using the foil shielded triple wire they supply but can't seem to >find it, can someone refresh my memory? > >Trying to find the cleanest way to do something with the drain wire and >also suggested wire sizes going out to the nav/pos lights (do I really >need an independent ground to the single point firewall ground or will a >twisted pair work?). Extend the drain wire with a pigtail of 22 or 20AWG wire and ground to mounting screws that hold power supply on your airplane. If airplane is metal, ground power supply locally to airframe. If composite, a parallel route pair taken to vicinity of single-point ground is good . . . then break out (+) wire to continue on to strobe switch. Bob . . . ________________________________ Message 7 _____________________________________ Time: 07:33:00 AM PST US From: Scott Bilinski Subject: AeroElectric-List: Alt Field question --> AeroElectric-List message posted by: Scott Bilinski I have the crowbar OV module and relay installed and just found a possible problem. I was doing a engine run up and tried to turn on the Alt Field, It would not turn on. On the next engine run up I turned the field on before engine start and everything is fine. If the Alt Field breaker pops for what ever reason I will not be able to reset it in flight. Is this normal? Unfortunately I followed the Van's wiring before I got turned onto the Aero Electric book. Scott Bilinski Eng dept 305 Phone (858) 657-2536 Pager (858) 502-5190 ________________________________ Message 8 _____________________________________ Time: 07:52:44 AM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Fastons --> AeroElectric-List message posted by: "Eric M. Jones" Bob (et al), I've read your various epistles on Fastons and I fully agree. My experience is that the Faston to quick-fit connections are superior in many ways to most other fastening methods. I do a lot of design with Fastons and Mosfets that invariably leads to the issue of how much current a female Faston and the mating pcb "quick-fit" terminal is rated for. Info is hard to come by. My presumption is -- if Fastons are sold in AWG 10 sizes-- then it is only reasonable that the proper quick-fit terminal should be assumed to carry the rated AWG 10 ampacity. (Which depends more on the wire insulation melting point than anything else.) Aye??? Good reference on ampacity---http://www.allaboutcircuits.com/vol_1/chpt_12/3.html (Faston is a trademark of Aircraft & Marine Products). Regards, Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 Phone (508) 764-2072 Email: emjones@charter.net For every complex problem, there is a solution that is simple, neat, and wrong. - H. L. Mencken ________________________________ Message 9 _____________________________________ Time: 07:57:36 AM PST US From: "Robert L. Nuckolls, III" strobe/nav/pos lights Subject: RE: AeroElectric-List: wiring Nova and Aeroflash strobe/nav/pos lights --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" strobe/nav/pos lights > >Twisted pair isn't designed to reduce radiated noise. The conductors don't >actually block one another from transmitting, at least not much. You need >coaxial, or some other type of surround-shielding for that. (How that >works is a Physics question, pick up any Electricity and Magnetism text >for a lecture on one of the more boring aspects of electricity, unless you >love math.) Actually, noise propagation modes are equal in both directions. A single strand of wire in space has the same ability to radiate noise as it does to pick it up. The only difference between the wire's role in a noise problem is whether it carries signals of a potential victim system or antagonist system. So, twisting is a good thing to do to ward off noises that propagate MAGNETICALLY while shielding puts a muzzle on ELECTROSTATIC dragons. >Back to your original questions: >1. B&C sells foil shielded three-wire cable. Unfortunately, nothing larger >than 22AWG, so check the power requirements for your lights. B&C's shielded wires are braided and yes, they are 22AWG. Members on the list have reported good results with substituting this wire for the fatter Beldfoil, PVC insulated wire shipped with most strobe kits. Also, within the last few weeks, someone posted a mail-order source for the Beldfoil wire by the foot. I'd appreciate a repeat post. I'll file it away in a more accessible location. >2. Connect the drain wire to ground on ONE END of the cable (preferably at >a single-point ground near the battery). I doubt that any installation manual for a strobe system has suggested extending the shield this far. It's designed to carry VERY TINY currents generated by capacitive coupling between bundles and can be taken to any convenient local ground . . . for strobes this is usually case ground at the power supply's mounting bolts. Are you in possession of installation instructions for the Nova system? What do they show? Bob . . . ________________________________ Message 10 ____________________________________ Time: 07:59:32 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Current Limiters --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:43 PM 10/27/2003 -0700, you wrote: >--> AeroElectric-List message posted by: "Matt Prather" > > >I might not understand your question exactly, but I think you >are asking whether the shunt can be damaged by running too much >current through it. . . . > . . .its probably still >okay, and 4W (that's 80A) might be okay with the shunt too, though >Amperage readings might get a little wacky because of heating. > >So, I don't think you need a current limiter to protect the shunt, >though you may want one for other design considerations. > >Hope that helps. A well crafted answer sir. Thank you. Bob . . . ________________________________ Message 11 ____________________________________ Time: 10:00:02 AM PST US From: "Rick Caldwell" Subject: Re: AeroElectric-List: BUS / Fuse Blocks --> AeroElectric-List message posted by: "Rick Caldwell" David, My RV-6 has a sliding canopy so the bulkhead behind the panel is where I mounted the fuse blocks. Since I have the RMI uMonitor, I had space left in the panel for a nice sized storage box on the right side. I made the rear wall of the box a door that swings out for access to the fuses. Rick Caldwell RV-6 136RC One Design 137RC >Where are the RV6 / 7 builders putting the primary and secondary fuse >blocks in the aircraft? I'm having a difficult time finding room for >the two regulators and fuse blocks and need some creative help. > >Regards, > >David >RV6-A (wiring) Add MSN 8 Internet Software to your current Internet access and enjoy patented spam control and more. Get two months FREE! ________________________________ Message 12 ____________________________________ Time: 10:17:46 AM PST US Subject: Re: AeroElectric-List: BUS / Fuse Blocks From: --> AeroElectric-List message posted by: On my -6 slider, I have a hinged panel mounted between the instrument panel and first bulkhead. The hinge is at the bulkhead, allowing the panel to swing down after removing the knobhead screw/nutplate securing it at the panel. Main fuse block is mounted to this panel, easy to service. Secondary block (always hot) is mounted on the topmost portion of the firewall recess. Pic on request if my explanation is confusing . Rob Acker (RV-6 flying) do not archive > Where are the RV6 / 7 builders putting the primary and secondary fuse > blocks in the aircraft? I'm having a difficult time finding room for > the two regulators and fuse blocks and need some creative help. > > Regards, > > David > RV6-A (wiring) ________________________________ Message 13 ____________________________________ Time: 11:46:51 AM PST US From: Joa Harrison Subject: RE: AeroElectric-List: wiring Nova and Aeroflash strobe/nav/pos lights --> AeroElectric-List message posted by: Joa Harrison The Nova instructions aren't the best and don't even show connections to the strobes, only to the unit. Here's the instructions neverless... http://www.strobe.com/pdfs/eps40X-install.pdf Joa ++++++++++++++++++++++++++++++++++++++++++++++ Are you in possession of installation instructions for the Nova system? What do they show? Bob . . . --------------------------------- Exclusive Video Premiere - Britney Spears ________________________________ Message 14 ____________________________________ Time: 12:00:11 PM PST US From: Pete Waters Subject: AeroElectric-List: Aircraft Configuration Spreadsheet chaskuss@bellsouth.net, Hebeard2@aol.com, lhelming@sigecom.net, aletherington@rogers.com, VE3LVO@rac.ca --> AeroElectric-List message posted by: Pete Waters Here y'all go. This is very rough right now; I'd say on the scale of Version 1.0 and Version 2.0, it's more like Version 0.5. But you get the idea. I'm also thinking of making, in PowerPoint or something like that, a paper block diagram of the airplane. It could be hyperlinked to the spreadsheet entries, so, fo example, if you clicked ont he "alternator" box on the block diagram, it would lead you to the entry in the spreadsheet. Also, vice-versa, from spreadsheet to block diagram. All in all this will involve a lot of mouse-clicking, and may be way too anal-retentive, but I think it's the best way to organize one's thoughts about the complex beasts that we're building and flying. I'm not smart enough to keep it all straight in my head. If anybody else wants a copy let me know. Pedro --------------------------------- Exclusive Video Premiere - Britney Spears ________________________________ Message 15 ____________________________________ Time: 12:44:02 PM PST US From: Carlos Sa Subject: AeroElectric-List: landing/taxi lights --> AeroElectric-List message posted by: Carlos Sa Hello, listers Does anyone have URL to headlights technical specifications? I have one 7610 and one 7606 (sealed beam halogen, round) that I was thinking on installing in the wings of my CH601, but noticed that many RVs use the MR-16. Wonder how they (and others, like JC Whitney's 88ZX9844X, http://www.aeroelectric.com/temp/4352.JPG , etc.) compare?? Any pointers? Thanks in advance Carlos Sa Montreal, Canada Ch601-HD, plans ________________________________ Message 16 ____________________________________ Time: 02:56:32 PM PST US Subject: Re: AeroElectric-List: landing/taxi lights From: "Matt Prather" --> AeroElectric-List message posted by: "Matt Prather" Sylvania (among others) makes replacements for all of the standard halogen sealed beam headlamps. Information can be found here. Most of these lamps can be found in the automotive section at Walmart. http://www.sylvaniaautocatalog.com/sylvania/sealedbeams.asp# Regards, Matt- N34RD > --> AeroElectric-List message posted by: Carlos Sa > > Hello, listers > > Does anyone have URL to headlights technical specifications? > > I have one 7610 and one 7606 (sealed beam halogen, round) that I was > thinking on installing in the wings of my CH601, but noticed that many > RVs use the MR-16. Wonder how they (and others, like JC Whitney's > 88ZX9844X, http://www.aeroelectric.com/temp/4352.JPG , etc.) compare?? > > Any pointers? > > > Thanks in advance > > > Carlos Sa > Montreal, Canada > Ch601-HD, plans > > ________________________________ Message 17 ____________________________________ Time: 02:58:09 PM PST US From: Jim Sower Subject: AeroElectric-List: Inductive current measuring device .... --> AeroElectric-List message posted by: Jim Sower When I was in the auto repair business (long ago in another life) there were inductive current measuring devices that clamped over, say, an alternator B+ lead and measured output pretty accurately. I don't want to run an extra 10' run of wire just to have an ammeter. I would prefer to have a pickup on the B+ cable just before the Alt-Mstr wired to the panel with 24 awg. Then I could wire the other side of Alt-Mstr to battery and one long line to the buss' up front. Needs to be very affordable, moderately accurate and easy to install ... Jim S. Jim Sower Crossville, TN; Long-EZ N83RT, Velocity N4095T ________________________________ Message 18 ____________________________________ Time: 03:14:13 PM PST US From: Carlos Sa Subject: Re: AeroElectric-List: landing/taxi lights --> AeroElectric-List message posted by: Carlos Sa Matt, thanks for the input. I had searched the Osram-Sylvania site, as well as the GE site ( http://catalog.gelighting.com ), but I only found mechanic and electrical specs. What I'd like is to get photometric data (a luminous intensity polar graph would do) and see how these different products compare. Cheers Carlos do not archive --- Matt Prather wrote: > Sylvania (among others) makes replacements for all of the standard > halogen sealed beam headlamps. Information can be found here. Most > of these lamps can be found in the automotive section at Walmart. > > http://www.sylvaniaautocatalog.com/sylvania/sealedbeams.asp# > > Regards, > > Matt- > N34RD ________________________________ Message 19 ____________________________________ Time: 03:46:39 PM PST US From: BAKEROCB@aol.com Subject: AeroElectric-List: Run away alternator scenario --> AeroElectric-List message posted by: BAKEROCB@aol.com 10/28/2003 Hello Bob Nuckolls, Below is a copy of a previous posting on the list. Can you please comment on the validity of this scenario and the proposed solution? Thank you. 'OC' Baker, Builder of KIS TR-1 #116 4/14/97 - ?/?/? ----------------------COPY OF 03/29/03 POSTING FOLLOWS---------------------------------- < Subject: AeroElectric-List: Alternator Systems ...................SKIP...............We've got an external voltage regulator powered via a 5 amp field supply breaker. However, virtually all light aircraft then power the field breaker from the battery side of the 'B' lead fuse/breaker (typically 40 to 60 amps rating). If this main breaker/fuse opens, the VR senses low voltage and maximizes alternator field current in the impossible attempt to restore 13.8 to 14.5 volts on the disconnected buss. The result is 100+ volts at the alternator B terminal and sometimes severe alternator damage involving the faults mentioned. In my opinion, the field supply breaker should be powered from the alternator side of the main breaker. Regards, Mike>> ________________________________ Message 20 ____________________________________ Time: 04:27:53 PM PST US From: "Eric M. Jones" Subject: AeroElectric-List: Inductive current measuring device .... --> AeroElectric-List message posted by: "Eric M. Jones" >there were inductive current measuring devices that clamped over, say, an alternator B+ >lead and measured output pretty accurately. >Jim Sower Jim, It used a hall effect sensor (for AC you can use a clamp-on transformer...) There aren't many ways to do this job, but this looks like a good one. See these guys. http://www.allegromicro.com/hall/currentsensor.asp Eric ________________________________ Message 21 ____________________________________ Time: 04:52:34 PM PST US From: "Ernest Kells" Subject: Re: AeroElectric-List: Current Limiters --> AeroElectric-List message posted by: "Ernest Kells" Bob, Matt and others: Let me state my question with a little more info - I basically don't even know the question but I think I need to understand this now. I am using your Z-2 diagram with the always hot bus. I have a large Prestolite alternator (installed) that I would like to limit for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to keep the alternator. It is a tight fit - but it does fit. Note: almost all work - engine with all appliances and prop hardware, cowling, wiring, heat shields, etc., are finished. Change at this stage is not easy. I have installed the Vans 40 amp shunt, wire, busses, etc., based upon an overall 40 amp design. Matt Prather stated "I might not understand your question exactly, but I think you are asking whether the shunt can be damaged by running too much current through it........." That's my question! But his beautiful answer just confuses me. All I know is that I have a voltage regulator and OVM to limit the voltage. It seems like I should have a mechanism to limit the amperage output from 70 to no more that 40 amps. The only "mechanism" I have in the electron stream is a 40 amp shunt (a piece of Bakelite with a flat bar). Do I just need a simple 35 or 40 fuse/circuit breaker on the main bus (#8 wire from battery contactor) ??? Thanks for any help in knocking down this mental block. Ernest Kells - RV-9A O235-N2C, Wood Prop 90 plus % Complete - electrical ________________________________ Message 22 ____________________________________ Time: 05:00:55 PM PST US From: MikeM Subject: AeroElectric-List: Re: Ground Loop --> AeroElectric-List message posted by: MikeM > From: "Michel RIAZUELO" > I have heard about "ground loop". Who can tell me more or > indicate where are the things I have to read ? Michel, In the context of airplanes, the goal when installing radios, intercoms, and entertainment systems is to NOT hear alternator whine, strobe squeal, electric gyro brush noise, and magneto pulses in your headphones (or have others hear these noises in your radio transmissions). An installation which has the audio contaminated with these undesirable noises is said to have "ground loops" (the most likely cause), while one where the audio is "clean" does not. In most metal airframes, the airframe itself is used as a conductor for the minus side of the power distribution. Each device has a short minus wire which is grounded locally, or some devices (like strobe power packs) ground through the case. In non-metallic airframes, you have to explicitly run minus supply wires to these remote devices. You get to choose if each of these runs all the way back to the battery minus terminal (radial grounds), or if you run a heavy ground bus from the battery minus terminal, and then ground the remote devices to this (ground tree). As far as keeping noise out of the audio, the former is preferable, but not absolutely required. In a metal airframe, you don't get that choice. If the current flowing to/from these remote devices happens to have frequency components in the audible range (alternator ripple, strobe power supply, gyro brushes, magneto Primary leads), and there is some way for these currents to "couple" into the audio wiring, then you would hear the noise mixed with whatever audio you are listening to... The goal when installing is to prevent "coupling" between the noise currents and the audio system. Both airframes and copper ground trees are slightly resistive, and the current flowing to/from the various devices causes a voltage drop along the airframe/ground tree wiring. In a well designed ground distribution system, the ground drops may be only a few tens of milliVolts (mV), but that is enough to contaminate the audio if these drops are allowed to "couple" into the audio wiring. In the worst case, the ground drops might be as high as hundreds of mV. A bad example of this is in my Cessna 182, where a 60A alternator is mounted on the engine, and the battery is mounted in the aft end of the fuselage (for weight distribution). The alternator puts out 60A of audible ripple current, which flows from the ground stud of the alternator, through the ground strap to the engine crankcase, through the engine, through another ground strap across the rubber engine mount to the motor mount cradle, to the fire wall, along the fuselage under the cabin floor to the aft fuselage, to the battery ground strap, and finally into the minus terminal of the battery. Imagine taking two very long clip leads; connect one to the alternator frame, and the other to the battery minus terminal. Bring the other two ends of the clip leads into the cabin, and connect them to the tip and barrel of a standard aviation headset which you are wearing. Now start the engine and make sure the alternator is charging. The total ground voltage drop between the clip leads (alternator all the way to the battery minus) will be plainly audible in the headset. Obviously, the ground drop is large enough to create a voltage signal level almost as big as what would normally be driving the headsets. So how do you prevent the noise sources from "coupling" into the audio system? Some people think that the coupling is inductive or capacitive, and that "shielding" is key to eliminating contaminated audio. Others think that "filtering" the noise sources is the key, but both of these methods are only secondary, and rarely fix the underlying problem. The primary cause of audio contamination is allowing the audio system to connect to the airframe power ground (or ground wiring) at more than ONE location (violating the principle of "single point ground"). If the audio system connects into the current carrying ground system at multiple places ("ground loop"), the ground voltage drops that exist between the multiple grounding points can add in series with the audio signals, just like the clip leads/headphone test above. Mic audio level is only a few hundred mV, so it is easy to get a few tens of mV of alternator ripple between the radio stack and the airframe point where the mic jack is "grounded" if you don't take steps to prevent the mic jack sleeve from coming in contact with the airframe. The correct way to wire your audio is to have a completely separate ground wire between each disparate audio item, and then cross tie this whole "floating audio ground" to the airframe (in a metal airframe) or to the power ground bus (in a non-metallic airframe) in just exactly ONE place... This avoids having the power ground drops appearing between a radio output and its headphone jack, for example. This requires some mechanical ingenuity. For example, when mounting mic and headphone jacks, you have to use insulating shoulder washers to keep the threaded sleeve from touching the airframe. Since they are not locally grounded, an additional ground wire from each jack has to run back to the intercom/audio panel... Usually, I use shielded wire for all of the jack wiring, where the shield is used for the jack sleeves, and the conductors inside are used for PTT, Mic Tip, R and L headphone. Okay, so we now understand "single point ground", but what happens in the radio stack? It turns out that all of the standard avionics (King, Garmin, UPSat, Narco, uAir) connects the audio and power grounds internally to the case of each radio, which contacts the tray, which is grounded by virtue of the rack being fastened into the rails in the panel, which is in turn connected to the airframe structure. You get no choice about this, you are stuck with it, especially in a Cessna or Mooney. If you are creating the panel yourself, then maybe you can control things. When installing your radios/audio panel into a metal aircraft, the radio rack stack becomes the defacto single point ground for the entire audio/avionics suite. When you make your audio wiring harnesses, you have to take this into consideration. The best you can do is not allowing any of the remotely mounted parts of the audio system from contacting the airframe locally. This is why the cabin speaker needs to have two wires running from it to the audio panel, one of which is grounded at the rear of the audio panel. Why each mic and headphone jack brings its sleeve all the way to the rear connector of the audio panel/intercom, etc, etc. In a non-metallic airplane, you could use the instrument panel as a ground plane for all of the radios/audio stuff, and purposefully keep the alternator and strobe currents out of the panel area. Don't ground the electric gyros to the panel (ie run the gyro minus lead more directly to the battery minus). This raises some interesting problems. For example, suppose you have a nice clean audio system (no whine or squeals), and you want to add a CD player/AM/FM entertainment system that you want to power from the aircraft power. Your stack is full, so you have to mount the CD system someplace else, like in the center console. The CD system has an "audio ground" and it has a "power ground" pin. Where do you tie these? First, take an Ohmmeter, and measure between the CD system's audio and power ground pins, and the case. There is a 99% probability that the cheapskate who designed it tied both of these to the CD system's case, which poses the following dilemmas: When you screw the CD system into the console (assuming a metal mounting structure), for better or worse, you have now tied the CD system to a ground removed from the one that the rest of all your radio stack is tied to. If there is a big preexisting ground drop in the airframe between the radio stack and the center console, then you are screwed, because there is nothing you can two with the as yet unconnected CD system audio and power ground wires which will undo this. The only hope is to "isolate" the CD system by using some sort of insulating mounting which keeps it from grounding through its case. Now you still have two "ground" wires to hook up. The only place where these can be connected without violating the "single point ground" for the entire audio system is to tie the power ground to the rails of the radio rack (same place as where the radios are presently grounded), and tie the audio ground to the audio panel. Space permitting, you are way better off mounting the CD system in the center radio stack where it doesnt matter if its case touches the rails. So, in summary: When wiring a metal airframe, use the airframe as the ground return path for all non-audio stuff. Mount all of your radios/audio panel/intercom/entertainment in the radio stack. Connect the power grounds from all the avionics to a single point electrically connected to the rack assembly. Connect all of the audio grounds to the rear of the audio switching panel. Tie all sleeves from remotely-mounted isolated mic/headphone jacks to the intercom which in turn should be grounded only to audio switching panel. Any other piece of audio equipment should be "floated" locally, its power ground tied to the radio racks, and its audio ground brought up to the switching panel. When wiring a non-metallic airframe, connect all of the non-audio stuff to a network of ground wires where ultimately each item has a path back to the minus terminal of the battery. Since some of these paths may be shared, the current carrying capacity of the ground wires has to be considered. When wiring all of your avionics/audio items, tie all grounds (both power and audio) to a single point located on or near the radio rack(s). Tie just ONE single jumper wire from the radio grounds to the power ground bus. Mike Mladejovsky, PhD EE Skylane '1MM Pacer '00Z ________________________________ Message 23 ____________________________________ Time: 05:03:06 PM PST US From: Alex Balic Subject: AeroElectric-List: coax terminations and grounding a pusher --> AeroElectric-List message posted by: Alex Balic I am trying to attach some connectors to my RG59 coax- the connectors come with 3 pieces- the body which fits over the inner insulator (and possibly under the outer sleeve), the conductor tip, and the crimp sleeve. Although the sleeve fits over the cable easily, it won't even come close to fitting over the cable sheath/connector body, after the body is inserted into the cable end- is this supposed to be assembled by removing the jacketing leaving only the braid, and crimping that down to the body? it would seem that that would be a weaker system than leaving the jacketing on, but really, it doesn't even come close to sliding over once the body is inserted- am I missing something here? I looked in the book, but all of the connector types there use threaded connectors, which I can go and get too I suppose, but I have these on hand. Also, about the grounding , it is mentioned that a composite pusher aircraft leads to ground loops on the engine instruments, but I could not find a good solution to this presented other than increasing the wire diameter- I have a ground through the firewall, and will have a second in the front- which could come directly from the battery, and not have to come to the front from the rear ground - is this correct? I don't want to have a problem with the indications on my instruments... ________________________________ Message 24 ____________________________________ Time: 05:59:05 PM PST US From: "Robert L. Nuckolls, III" strobe/nav/pos lights Subject: RE: AeroElectric-List: wiring Nova and Aeroflash strobe/nav/pos lights --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" strobe/nav/pos lights At 11:46 AM 10/28/2003 -0800, you wrote: >--> AeroElectric-List message posted by: Joa Harrison > > > >The Nova instructions aren't the best and don't even show connections to >the strobes, only to the unit. > >Here's the instructions neverless... > >http://www.strobe.com/pdfs/eps40X-install.pdf Okay, I just dropped them a note to ask what their recommendations were with respect to shield grounds. Bob . . . ________________________________ Message 25 ____________________________________ Time: 06:04:59 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: coax terminations and grounding a pusher --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 06:59 PM 10/28/2003 -0600, you wrote: >--> AeroElectric-List message posted by: Alex Balic > >I am trying to attach some connectors to my RG59 coax- RG59???? this is television coax . . . 75 ohm, I'd hope you were dealing with RG-58 and better yet, RG-400 >the connectors come >with 3 pieces- the body which fits over the inner insulator (and possibly >under the outer sleeve), the conductor tip, and the crimp sleeve. Although >the sleeve fits over the cable easily, it won't even come close to fitting >over the cable sheath/connector body, after the body is inserted into the >cable end- is this supposed to be assembled by removing the jacketing >leaving only the braid, and crimping that down to the body? it would seem >that that would be a weaker system than leaving the jacketing on, but >really, it doesn't even come close to sliding over once the body is >inserted- am I missing something here? I looked in the book, but all of the >connector types there use threaded connectors, which I can go and get too I >suppose, but I have these on hand. See http://www.aeroelectric.com/articles/bnccrimp.pdf >Also, about the grounding , it is mentioned that a composite pusher aircraft >leads to ground loops on the engine instruments, but I could not find a good >solution to this presented other than increasing the wire diameter- I have a >ground through the firewall, and will have a second in the front- which >could come directly from the battery, and not have to come to the front from >the rear ground - is this correct? I don't want to have a problem with the >indications on my instruments... Do you have a copy of the AeroElectric Connection? If not, at least download the update chapters available from my website. This one on grounding at: http://www.aeroelectric.com/articles/Rev9/ch5-9.pdf and this on system architecture at: http://www.aeroelectric.com/articles/Rev10/z10.pdf and this on system reliablity at: http://www.aeroelectric.com/articles/Rev9/ch17-9.pdf If you find these chapters useful, then I'd recommend you get the whole book at http://www.aeroelectric.com/Catalog/AECcatalog.html Bob . . . ________________________________ Message 26 ____________________________________ Time: 06:06:08 PM PST US From: "David Schaefer" Subject: AeroElectric-List: AMP / Cannon Connectors --> AeroElectric-List message posted by: "David Schaefer" Bob .. this may be more of a philosophical question vs. a 'best electrical practices' question. I've always been taught not to 'break' a wire if it can be avoided i.e. a solid wire was better than two pieces. However, now that I've got miles of wire strung out I'm becoming enamored with cannon connectors both bulkhead and in-line to make my life easier and make the airplane more serviceable when I'm on my back under the panel! When I look at 'production' planes from 747's to F-16's I see gaggles of cannon-type plugs and they seem to have workable electronics. What are the plusses and minuses of using these connectors? Breaking wires? I've got access to good gold-plated pins etc. Regards, David ________________________________ Message 27 ____________________________________ Time: 06:15:43 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Current Limiters --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" At 07:44 PM 10/28/2003 -0500, you wrote: >--> AeroElectric-List message posted by: "Ernest Kells" > > >Bob, Matt and others: > >Let me state my question with a little more info - I basically don't even >know the question but I think I need to understand this now. I am using >your Z-2 diagram with the always hot bus. > >I have a large Prestolite alternator (installed) that I would like to limit >for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to keep the >alternator. It is a tight fit - but it does fit. Note: almost all work - >engine with all appliances and prop hardware, cowling, wiring, heat shields, >etc., are finished. Change at this stage is not easy. I have installed the >Vans 40 amp shunt, wire, busses, etc., based upon an overall 40 amp design. There is no practical way to de-rate an alternator. If it's a 70A machine, then there are times when your airplane's electrical system will demand and get all 70A out of it and then some. So if it's a 70A machine, wire it up like you're going to use it all even if you don't intend to. 4AWG b-lead feeder and ANL-60 limiter is recommended. >Matt Prather stated "I might not understand your question exactly, but I >think you are asking whether the shunt can be damaged by running too much >current through it........." > >That's my question! But his beautiful answer just confuses me. All I know >is that I have a voltage regulator and OVM to limit the voltage. It seems >like I should have a mechanism to limit the amperage output from 70 to no >more that 40 amps. The only "mechanism" I have in the electron stream is a >40 amp shunt (a piece of Bakelite with a flat bar). Do I just need a simple >35 or 40 fuse/circuit breaker on the main bus (#8 wire from battery >contactor) ??? None of those devices have any control over the alternator's output. Generators will willingly deliver more than their rated current (burns brushes, throws solder off the commutator) so generator output was indeed limted by features built into the regulator (See Chapter 4 in the 'Connection). Alternators are inherently current limited by their magnetic design (See chapter 3 of the 'Connection) so there is no need for an alternator regulator to sense alternator load current . . . much less do anything about it. The 40A shunt will be just fine . . . but there will be short periods of time after engine starting that the loadmeter will be "pegged" until the battery charges up. This is not a big deal. Bob . . . ________________________________ Message 28 ____________________________________ Time: 06:23:24 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Fwd: Reply from Nova RE: Installation Diagrams --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" Just got this response from Nova as to their recommendations for shield ground treatment. Steve didn't mention why it wasn't covered in the installation manual but his recommendations were consistent with my own . . . Bob . . . >Subject: RE: Strobe System Installation Diagrams >Date: Tue, 28 Oct 2003 18:54:51 -0500 >X-MS-Has-Attach: >X-MS-TNEF-Correlator: >Thread-Topic: Strobe System Installation Diagrams >Thread-Index: AcOdluDGjX/2Lyz4QsiUJHK/bHwxPgAF7Pqg >From: "Stephen Hanley" >To: "Robert L. Nuckolls, III" >Cc: "Kimberly Fritsch" , > "Eugene Abel" , > "Sandy Havens" > >Dear Bob: > >Thanks for the email. The shields are normally used in environments >where radio frequency interference is a problem. If you choose to use >the shields, ground them at the power supply only - to chassis ground. >Leave the opposite ends disconnected - most customers trim them off. > >Thank you. > >Sincerely, > >Steve for Team Nova >-----Original Message----- >From: Robert L. Nuckolls, III [mailto:bob.nuckolls@cox.net] >Sent: Tuesday, October 28, 2003 4:02 PM >To: Nova >Subject: Strobe System Installation Diagrams > > >Good day! > >A am looking at installation instructions for your >which I downloaded from: > >http://www.strobe.com/pdfs/eps40X-install.pdf > >I can find no recommendations for how the shield grounds >are to be treated in the strobe-head-to-power-supply cables. Can you >enlighten me? > >Thanks! > > Bob . . . ________________________________ Message 29 ____________________________________ Time: 06:32:39 PM PST US Subject: Re: AeroElectric-List: Current Limiters From: "Matt Prather" --> AeroElectric-List message posted by: "Matt Prather" Hi Ernest, Aha... Okay, now I see what you are getting at. I don't think there is an effective means for 'throttling' an alternator to a certain current output. The alternator is controlled by a VOLTAGE regulator. This means that in response to a varying load, the regulator is going to try to adjust the ammount of current coming out of the alternator to keep the VOLTAGE within the specified range (usually about 14V). The bigger the load on the bus, the larger the initial sag, and the larger response from the regulator. This will continue until the alternator is max'ed out (around 70A). In your airplane, the only time I can see you exceeding your power budget is when you are charging a dead battery. So, here's what I would do... Ditch the 40A shunt and meter. Get a 75A shunt from somewhere (BandC has them for $25), and a meter that reads in percent (-100-0-100). The meter will indicate full scale when it recieves 50mV from whatever shunt you install (75A) in this case. This way, you have the advantage of being able to use the full rated output of the boat anchor that you are paying to haul around. That will be nice when you install heated seats, and a mondo landing light. Plus, the bigger shunt weighs no more, and is the same price as the 40A. If you run the battery flat, the 70A alternator will charge it much faster than if you were to successfully regulate the 70A down to 40A. The cheap way might be to keep the meter that you have, and just replace the shunt... Then, if the meter says 40A, the circuit is really moving 75A... Kind of lame though. If the meter says 20A, then you have 37.5A. The really cheap way is don't do anything, but just run it, it may eventually break the mechanism in the meter from knocking the needle against the stop... I bet you would get away with it for a while though. How often will the alternator need to put out more than 40A?? Only if something bad happens. A shunt isn't designed as a current limiter or regulator in any way. Its only purpose is to provide a means for MEASURING current through a section of a circuit. It is instrumentation, only. Ideal instruments shouldn't effect the behavior of the system being measured. The ideal shunt/ammeter would cause 0 voltage drop in the circuit, but 50mV is acceptable, Current limiters are designed to only work when there is some kind of malfunction on the bus. I don't believe they would be good to use as another form of regulation. How's that? Regards, Matt- N34RD > --> AeroElectric-List message posted by: "Ernest Kells" > > > Bob, Matt and others: > > Let me state my question with a little more info - I basically don't > even know the question but I think I need to understand this now. I am > using your Z-2 diagram with the always hot bus. > > I have a large Prestolite alternator (installed) that I would like to > limit for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to > keep the alternator. It is a tight fit - but it does fit. Note: almost > all work - engine with all appliances and prop hardware, cowling, > wiring, heat shields, etc., are finished. Change at this stage is not > easy. I have installed the Vans 40 amp shunt, wire, busses, etc., based > upon an overall 40 amp design. > snip > It seems like I should have a mechanism to limit the amperage output > from 70 to no more that 40 amps. The only "mechanism" I have in the > electron stream is a 40 amp shunt (a piece of Bakelite with a flat bar). > Do I just need a simple 35 or 40 fuse/circuit breaker on the main bus > (#8 wire from battery contactor) ??? > > Thanks for any help in knocking down this mental block. > > Ernest Kells - RV-9A O235-N2C, Wood Prop > 90 plus % Complete - electrical > ________________________________ Message 30 ____________________________________ Time: 07:12:07 PM PST US From: "George" Subject: Re: AeroElectric-List: Aircraft Configuration Spreadsheet --> AeroElectric-List message posted by: "George" Pete Waters; You might try to get a copy of the older (free) version of the (now Microsoft owned) VISIO program. This usually came with a great many symbols that could be used to illustrate nearly any kind/type of diagram or chart that a person could imagine. Of course, text and descriptions of each item, as well as layers, or levels within the project are easily done too. About the easiest, and best, "inexpensive" prog that I've ever seen, for its' capabilities. George P.S.: Of course since MS realized the value of this program, they have purchased the rights to it, and added the appropriate value for it to the consumer's required input for usage. --- ________________________________ Message 31 ____________________________________ Time: 07:53:54 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Run away alternator scenario --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" > >...................SKIP...............We've got an external voltage regulator >powered via a 5 amp field supply breaker. However, virtually all light >aircraft then power the field breaker from the battery side of the 'B' lead >fuse/breaker (typically 40 to 60 amps rating). >If this main breaker/fuse opens, the VR senses low voltage and maximizes >alternator field current in the impossible attempt to restore 13.8 to 14.5 >volts on >the disconnected buss. The result is 100+ volts at the alternator B terminal >and sometimes severe alternator damage involving the faults mentioned. In my >opinion, the field supply breaker should be powered from the alternator side >of the main breaker. Regards, Mike>> This has circulated around the lists for years. The scenario is true IF you open the b-lead breaker without also shutting off the field . . . and this can be REALLY important for the majority of certified airplanes where the b-lead breaker is designed to nuisance trip (see chapter 17 of the 'Connection). Modern OBAM aircraft designs provide sufficient headroom in b-lead protection to prevent the dreaded condition cited. So, the only time we expect b-lead protection to open is when shorted diodes or some other serious malady has befallen the alternator in which case, the thing needs to be worked on anyhow. The design goal is to protect the AIRPLANE from the alternator, not protect the alternator from itself. By eliminating the probability of nuisance tripping the b-lead protection, concerns cited in this anecdote are alleviated. Bob . . . ________________________________ Message 32 ____________________________________ Time: 09:16:46 PM PST US From: Joa Harrison Subject: Re: AeroElectric-List: Fwd: Reply from Nova RE: Installation Diagrams --> AeroElectric-List message posted by: Joa Harrison Thanks a bunch Bob. Good to get confirmation. Can I have you look at one more thing? http://www.aeroflash.com/156-0049.pdf Why do I have to run a ground wire to the black wire when the nav and strobe lamps are internally grounded to the case? Can I just ground the black wire to the case or should I run a ground wire all the way from the grounding block on the firewall? Or perhaps run a ground wire from the strobe supply (that is also connected to the supply mount and the drain wire)? In the Aeroflash FAQ ( http://www.aeroflash.com/faq.html ) it says to use shielded wire to run to the power supply. Is this necessary and/or beneficial? BTW I *finally* finished all my Microair radio wiring tonight including using the two relays exactly per your diagram. Works like a charm and I'm very pleased! Thanks for the help! Joa ++++++++++++++++++++++++++++++++++++++++ heir recommendations for shield ground treatment. Steve didn't mention why it wasn't covered in the installation manual but his recommendations were consistent with my own . . . --------------------------------- Exclusive Video Premiere - Britney Spears ________________________________ Message 33 ____________________________________ Time: 09:35:57 PM PST US From: "Kingsley Hurst" Subject: AeroElectric-List: Fuse Holders --> AeroElectric-List message posted by: "Kingsley Hurst" Bob, I recently purchased your "AeroElectric Connection" book and firstly wish to congratulate and thank you for producing this excellent publication for "first timers" like myself. It has been invaluable. I am going to adopt most if not all of your ideas including fast-on connectors and blade fuses etc. Whilst I have no violent objection to having the fuse holders behind the panel, I would prefer access to them from in front of the panel simply to make life easier if one suspects a blown fuse. I have no desire to carry out inflight diagnostics and repairs. To this end, I have come across the 15710 Series Rear Terminal ATC Fuse Block by Bussmann Auto which I feel would be ideal for my purpose. It's properties including modular construction, dual buss option, rear access etc can be seen at http://www.bussauto.com/pdf/rta.pdf My question is, do you have any intention to stock these fuse blocks or alternatively, can you advise where I may purchase one or more of them given that I cannot find a distributor in Australia? Any assistance you or others may be able to offer would be much appreciated. Regards Kingsley Hurst Europa Builder in Oz