---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 05/14/08: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 02:25 AM - Re: PMA-6000 intercom 28V install (Etienne Phillips) 2. 04:55 AM - Re: Fuse Block Locations (RALPH HOOVER) 3. 06:36 AM - Re: Use of 700-2-10 switch for nav/strobe combo lights () 4. 07:50 AM - Re: Fuse Block Locations (Jim McBurney) 5. 08:38 AM - Re: PMA-6000 intercom 28V install (Robert L. Nuckolls, III) 6. 03:17 PM - Re: Fuse Block Locations (Henry Trzeciakowski) 7. 05:09 PM - Dual redundant electrical system (Terry McMillan) 8. 06:42 PM - Re: PMA-6000 intercom 28V install (Robert L. Nuckolls, III) 9. 08:55 PM - Re: Fuse Block Locations (Peter Laurence) ________________________________ Message 1 _____________________________________ Time: 02:25:28 AM PST US Subject: Re: AeroElectric-List: PMA-6000 intercom 28V install From: Etienne Phillips You're quite right Ralph, there is a noise concern. I doubt that the noise would be of a value that would cause damage, so my suggestion would be to try it, and if it doesn't work then replace it with a resistor... An alternative would be to use a switcher to get from 28V to 14V, then use an analogue voltage regulator to go to 12V. Something like a 7812 chip (connection details are identical to that of the switcher) would work quite nicely, and would only dissipate 2W at 1A, which is still somewhat better than 15W! You could also smooth the noise by putting a few (around 5) 100uF capacitors in parallel, upstream and downstream of the switching regulator. I suggest this rather than a two 500uF caps, as it will handle a much wider range of noise frequencies, as well as offer a degree of redundancy. They could even be wired into the loom at regular intervals between the bus, switcher and intercom ;-) I'm of a mindset that anything that gets hot will eventually cause problems somewhere... Also in case of an alternator failure, the last thing you want is for some minor component to start wasting precious energy by converting it to heat! I hope that this helps :-) Etienne On 09 May 2008, at 1:04 PM, RALPH HOOVER wrote: > Etienne, > > I suspect that PS engineering is using an analog regulator for > noise concerns (cost can figure in as well). Use care inserting a > switcher without properly considering the noise concern. A switcher > would certainly allow for a wide input voltage range without a lot > of heat. Not a show stopper but a design challenge to address. > This is just my take I have no knowledge of PS Engineering=92s design > or the process and decisions they have taken to arrive at their > design. I have used a switcher for my ANR power supply I=92ll soon > find out if I have any issues! > > Ralph & Laura Hoover > RV7A N527LR ________________________________ Message 2 _____________________________________ Time: 04:55:24 AM PST US From: "RALPH HOOVER" Subject: RE: AeroElectric-List: Fuse Block Locations Allen, I found it on the internet, I will search my records and see if I can find out where. I have lost a bunch of stuff due to a computer crash. I will be on the road for a few days so I will look when I return. It is a Bussman product 15710 series. Ralph -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Allen Fulmer Sent: Tuesday, May 13, 2008 10:10 PM Subject: RE: AeroElectric-List: Fuse Block Locations My favorite so far! And where, pray tell, did you get that beautiful fuse block with cover? Surely must be automotive! Allen Fulmer RV7 Avionics and Electrical >>>-----Original Message----- >>>From: owner-aeroelectric-list-server@matronics.com >>>[mailto:owner-aeroelectric-list-server@matronics.com]On >>>Behalf Of RALPH >>>HOOVER >>>Sent: Tuesday, May 13, 2008 8:43 PM >>>To: aeroelectric-list@matronics.com >>>Subject: RE: AeroElectric-List: Fuse Block Locations >>> >>> >>>John, >>> Here is yet another hinged option. This fuse block uses >>>insert able >>>crimped contacts (no fastons and one less electrical >>>interface). It is also >>>split 20 Main Buss, 8 Essential Buss. The two buses are tied >>>by a schottky >>>diode bolted to brass busses (the stuff in the center of the >>>rear of the >>>panel). The fuse panel swings down and forward from the >>>front edge of the >>>panel and all of the wiring is in the rear. >>> >>>Ralph & Laura Hoover >>>RV7A N527LR >>> >>>-----Original Message----- >>>From: owner-aeroelectric-list-server@matronics.com >>>[mailto:owner-aeroelectric-list-server@matronics.com] On >>>Behalf Of John >>>Morgensen >>>Sent: Tuesday, May 13, 2008 9:31 AM >>>To: aeroelectric-list@matronics.com >>>Subject: AeroElectric-List: Fuse Block Locations >>> >>> >>> >>>I am seeking pictures and advice on fuse block locations, >>>panel ground, >>>firewall ground, etc. My project is an RV-9A using a Z-13/8 >>>architecture. >>> >>>Thanks, >>>John Morgensen >>>775 771-5791 >>> >>> >>> >>> ________________________________ Message 3 _____________________________________ Time: 06:36:20 AM PST US Subject: RE: AeroElectric-List: Use of 700-2-10 switch for nav/strobe combo lights From: Thanks Bob, I have 2 more 2-10's on order from B & C. They are all new. Hopefully it's not a bad batch. Glenn Do Not Archive -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Tuesday, May 13, 2008 4:15 PM Subject: Re: AeroElectric-List: Use of 700-2-10 switch for nav/strobe combo lights --> At 03:30 PM 5/13/2008 -0400, you wrote: >I am using the 2-10 as defined in the manual to turn on the nav lights >in >the center position and then add the strobe lights in the up position. >Sounds simple enough. When I first turn on the nav lights, the strobe >lights start blinking. I then add the strobe lights to the nav lights and >they work normally. > >After cycling the switch once, only the nav lights come on at the first >position (desired) and I can add the strobe lights by moving the switch to >the top position. The behavior does not repeat itself unless the switch is >turned off for a period of time. The only thing that can cause unexpected sequencing is a faulty switch. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 4 _____________________________________ Time: 07:50:58 AM PST US From: "Jim McBurney" Subject: Re: AeroElectric-List: Fuse Block Locations Not building an RV, but worked on this same problem. I hinge-mounted a panel above the copilot's feet, but to eliminate a separate fuseblock cover I hinged mine at the firewall and Dzus'd it to the bottom flange of the instru panel, with the blocks on the upper side of the panel. Easy access on the ground, nothing to get bumped or kicked when closed. do not archive Blue skies and tailwinds Jim CH-801 DeltaHawk diesel Augusta GA 90% done, 90% left ________________________________ Message 5 _____________________________________ Time: 08:38:04 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PMA-6000 intercom 28V install At 08:23 PM 5/7/2008 -0700, you wrote: >PS Engineering s PMA-6000 intercom has the following note: > > >To reduce the amount of heat dissipated in the audio selector panel, when >used in a 28 > >Volt aircraft, it is required that the 15-Ohm, 15-Watt dropping resistor >(p/n 701-015-1501) be in- > >stalled in series with the power input. > > >The install manual goes on to say failure to do so will generate >unnecessary heat inside the unit and may void PS Engineering s warranty >. Does anyone have experience installing one of these units in a 28V >environment? Is the dropping resistor really required? The only reason I >ask is the local radio shops don t seem to know much about it which makes >me wonder if they ever used them. They all say they can order one but >nobody has one in stock. It is risky to disregard the words of the manufacturer's installation manuals. It's also disappointing that the manufacturers of this device did not craft a user-friendly design. The simplest thing to do is comply with the instructions. The simplest way to do this is acquire a component like this: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=FVTS10-15-ND Note that it can be mounted to some handy, out of the way surface on a long screw. The data sheet at: http://www.heiresistors.com/PDF/FVT_FST20%20spec.pdf tells us the hole through the middle of this device is 0.19" in diameter . . . The drill versus threaded sizes chart at: http://www.phy.mtu.edu/~suits/tapsizes.html says this is too small for a 10-32 screw but will be just fine for an 8-32. The resistor data sheet suggests we need one with 2" or so of over-all length. You'll be cranking a hard force down against a ceramic tube. Put a soft washer (some kind of rubber, plastic or even two layers of paper from the box that comes with a tube of toothpaste) between the end of the resistor and the mounting surface. Tighten the screw down to finger tight + 1 turn and spot the threads with some runny super-glue to keep it from drifting off that pressure setting. If your resistor comes with wires, clip them off. Attach lead wires for intercom power to the resistor's solder-tabs. Put double layer of heat-shrink over these joints for vibration support. This process has been used thousands of designs in various vehicular products including airplanes. Simple, lean, works as the manufacturer wishes and lasts a long time. BTW . . . the 15W rating is super conservative. The intercom may draw 1A peak current but the AVERAGE current will be much lower unless you're particularly fond of playing Wagner at 100dB in the headphones. Now, if you're REALLY wanting to make this more complicated, you can purchase one of B&C's DIM3-28 dimmers at: http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?10X358218#dim3-28 and instead of installing the dimmer potentiometer, you put the appropriate resistor between pins 1 and 3 to achieve a constant 14-volt output from the "dimmer". Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 6 _____________________________________ Time: 03:17:35 PM PST US From: "Henry Trzeciakowski" Subject: Re: AeroElectric-List: Fuse Block Locations John: I'm also building an RV 9tip-up, but I did not go with a hinged panel. My thought was that it should be very rare that I need to change fuses. If I do, it will be on the ground and all I'd have to do is back under the passanger side to change or troubleshoot. When I mounted them, I didn't take any pictures before I removed my sub-panel, but plan on it when I rivet my sub-panel on for the last time. That said, I mounted the Main Bus and Diode and heatsink (25watt - B&C) on the outboard side of the 745rib on the passanger side and used nutplates. I mounted the Eudurance Bus, which will basically be my avionics bus, on the inboard surface of the same rib. That way the e-bus will be just about 8 " from my avionic's stack. The Battery Bus I mounted just below the brake reservior and to the left of the battery. So'll I have a shor run to the Master Battery COntactor and no unfused wires penetrating the firewall. I purchased a fuse block with cover, so I wouldn't have issues with dirt, grease, etc. When I get pictures, I'll get them to you.. Henry ----- Original Message ----- From: "John Morgensen" Sent: Tuesday, May 13, 2008 6:30 AM Subject: AeroElectric-List: Fuse Block Locations > > I am seeking pictures and advice on fuse block locations, panel ground, > firewall ground, etc. My project is an RV-9A using a Z-13/8 architecture. > > Thanks, > John Morgensen > 775 771-5791 > > ________________________________ Message 7 _____________________________________ Time: 05:09:34 PM PST US From: "Terry McMillan" Subject: AeroElectric-List: Dual redundant electrical system This is my first time on the AeroElectric list server, though Ive been lurking in the forums for some time. Im looking for comments/critiques on a dual alternator dual battery system Ive designed. Right off the bat I have to acknowledge the contributions made in this area by Bob Knucolls, Ive read his book several times, and his ideas and philosophies have strongly influenced my design. Greg Richter of Blue Mountain Avionics has also been a major source of information and inspiration. My application is an all-electric plane, an RV7 Im building with Aerosance FADEC and an all-glass cockpit (AFS3400, GRT Horizon HX, and Trutrak EFIS). Im an electrical engineer with 22 years experience in a large electrical power utility doing protection and control work. Duplicate redundant protection systems for ultra high reliability are the core work in this field. In 1988 I left to start my own company, designing and manufacturing complex expensive microprocessor-based test equipment for use in that field. Ive flown my own Cessna 172 since 1992. Im comfortable with electricity and flying, but Im incorporating some non-standard ideas in this design and would appreciate comments. My prime concern is technical/safety aspects of the electrical system, but ergonomics is something Ive also considered important, and feel is too often neglected in the design of complex hardware systems. Ive attached reduced size jpg files to respect the bandwidth guidelines, based on the original dxf files, but will verbally describe the unusual aspects as well. I can also make available the dxf files showing clearer detail if anyone wants them. The first component after the battery in most aircraft systems is the master relay, which isolates both the starter solenoid and the feed to the main and/or essential buses. Its usually a large heavy solenoid that must be rated to carry starter current but normally carries only a small fraction of that current, and it takes about an amp to keep it picked up. My design uses a 60A ANL fuse at the battery, feeding a heavy-duty automotive 70A relay in the cockpit next to the master switch and fuse bus. I expect the smaller lighter relay will be more reliable than a $17 solenoid, especially because it is in a cooler lower vibration location, plus it will draw only one-tenth of the hold-in current which means more flying time in the event of battery only operation. In my specific system this is not insignificant, the 2 amp draw of two master relays would be ~10% of the typical main bus load. In a conventional system, there is no high-speed protection of the several feet of cable that can exist from the master relay through the firewall to the buses, other than how fast the pilot can smell smoking insulation and turn off the switch, by which time major damage can be done to the wiring bundle. Once I discovered ANL fuses, I saw they could offer fast automatic protection of this major cable run. There are some good photos at http://www.highrf.com/gallery/Power-Grids of a Legacy power grid using ANL fuses. In my system, because I require separate FADEC buses, Ive used an additional fuse plus relay and fuse bus mounted at the battery, to eliminate power wiring runs into and then back out of the cockpit, which cuts weight, simplifies wiring, and minimizes wiring exposure to damage. A reason given for the conventional system layout is that it can isolate a stuck starter solenoid. In my experience however, properly sized starter solenoids are far more likely to fail open than closed, especially since there is often an additional solenoid internal to the starter, and in worst case its an on-ground event. The master relays are controlled by double pole 3 position rocker switches with internal LED annunciators (see attached Switchgear.jpg). This allows replacement of the traditional split control switch by providing a battery only/alternator disabled configuration in the middle position, with the normal configuration in the upper position. Illuminated rocker switches, apart from being more visually appealing than the typical steel toggle switch, can provide rapid day/night visual confirmation of true operational status since the indicator is driven by the voltage of the actual controlled circuit. Arranging the switches in close functional groupings also makes it easy for pre-landing checks- just brush a finger across the tops of all the switches to verify they are in the upper position. >From there, power flows to the master bus via 60A Schottky diodes, which generate much less heat than conventional diodes, reducing heat sink requirements. There is only one main bus. I spent a lot of time trying to decide what would go on an essential bus and what would not, plus considering what kind of interlocks and switching would be necessary to operate from the essential bus. In the end, given my dual batteries, dual alternators, and better protection of the main battery feed lines, I realized that a large essential bus is just as secure as a small one, and not having to set up an emergency configuration during a high-stress situation is a big advantage. Greg Richters comments about unnecessarily complex emergency systems (page 7 of his Aircraft Wiring pdf) are spot on in my opinion. Modern avionics and LED nav & panel lights dont draw a lot of power, so normal daytime flight requirements are well under 20 amps for my setup, which can be carried by the 20A backup alternator, never mind the dual batteries. Many engine monitor systems, like the AFS3400, can monitor alternator loading and bus voltage plus provide programmable high/low limit alarms to these parameters, helping to keep track of loading during loss of a power source. I dont have an avionics master switch. I know this is controversial, and apposed to common procedure, but here is my rationale: 1) Modern avionics are not susceptible to switching transients the way a lot of earlier commercial gear was, especially during the early days of discrete transistors. Additionally, though its not shown on my schematics, diode suppression is fitted to all relays, something that wasnt usually done in the past. 2) A single avionics master switch provides a single contingency failure point for the avionics, after all the work to provide full redundancy. 3) Battery voltage drop during starting can cause some avionics to drop out, but because of the dual diode isolation of the main bus, the avionics will automatically be fed only from the normal-voltage alternate battery when the main battery sags during start. My fuel boost pump switch is a bit different in that there is an additional (AUTO) position, controlled by the FADEC system. However, takeoff/landing (MANUAL) position is up, consistent with the master switches, and as with them LED annunciators provide additional status information. There is no Pitot Heat control, this is a personal thing. Ive found that after flying the same plane for a while I rarely look at airspeed, and my setup gives me dual airspeed info plus AOA. Also, Im a VFR pilot. Doesnt mean I wont decide to add it if I hear compelling reasons to. Lighting is traditionally done with a row of toggle switches, one for every circuit, and here again I have departed from tradition, but in this case mainly with an eye to improved ergonomics. Details are on a separate drawing (Lights.jpg). Note that the labels on the rotary switch on the above panel layout jpg are one revision behind the schematic. I have shown just a 2-pole rotary switch, as high-reliability sealed switches usually have fewer configuration choices than cheaper switches. A single rotary switch, common in automotive applications, makes more sense to me than individual toggles. Just turn clockwise for more lights. The first position BEACON gives nav lights and strobes. Because strobes can be disorienting in reduced visibility they can be disabled via the STROBE ENABLE rocker switch, but the LED nav lights are always on given their miniscule power draw. APPROACH as shown energizes the landing lights in a wig-wag mode for high visibility, though this wouldnt appeal to everyone. TAXI and LANDING are the last two positions respectively. Taxi lights are on in both positions, but one rotation counterclockwise on the ground eliminates the long-range landing light to avoid glare to other pilots. The small rotary knob beside the larger lighting switch controls dimming of cockpit lights. The STROBE ENABLE rocker switch status LED gives instant visual confirmation of strobe status, and the tight group of 3 controls in their separate location can be operated by touch only, like the master and fuel boost controls. This is difficult to accomplish in the traditional row of identical toggle switches which are often mixed in with other identical toggle controls. I dont have panel controls for trim or flaps, these are provided on the pilot and copilot control stick handles. A junction box is provided as a convenient local plug-in terminus for the control stick switches, trim & flap servos and controller, radio control lines, and power/ground lines. I have a schematic of this if anyone wants to see it. My instrument panel will obviously have a lot fewer controls on it than is now common. I know that banks of toggle switches look impressive to the uninitiated, but realistically this doesnt contribute to safety by reducing the pilots workload. Colour coding and grouping can help a little bit, but it still leaves something to be desired for night operations and status checks by touch while keeping focused outside the cockpit. Thats about it for the design highlights. One thing not evident but also important is, wherever possible, separate physical routing of the main and alternate system wiring, including firewall penetrations. Ive tried to envision how the system would handle a variety of failures and havent come up yet with any realistic scenario that would bring the plane down before you could get to a reasonable destination point. My only minor concern at this point is how load sharing is controlled, since the secondary alternator is just 20A. Ive talked to Bill Bainbridge at B&C, and he said that he sets the voltage regulator about a volt lower on the alternate. This seems like a lot to me, Im not sure what effect this has on keeping the alternate battery in optimum condition. I couldnt find much in Bobs book or the forums on this point. Anyway, Im completely open to suggestions and/or criticism. Ego should never get in the way of safety. Id appreciate anything in the way of comment. Im now at the point of being almost ready to start wiring things up, and need a reality check that what I intend to do makes sense. Thanks, Terry McMillan ________________________________ Message 8 _____________________________________ Time: 06:42:06 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: PMA-6000 intercom 28V install At 08:23 PM 5/7/2008 -0700, you wrote: >PS Engineering s PMA-6000 intercom has the following note: > > >To reduce the amount of heat dissipated in the audio selector panel, when >used in a 28 > >Volt aircraft, it is required that the 15-Ohm, 15-Watt dropping resistor >(p/n 701-015-1501) be in- > >stalled in series with the power input. > > >The install manual goes on to say failure to do so will generate >unnecessary heat inside the unit and may void PS Engineering s warranty >. Does anyone have experience installing one of these units in a 28V >environment? Is the dropping resistor really required? The only reason I >ask is the local radio shops don t seem to know much about it which makes >me wonder if they ever used them. They all say they can order one but >nobody has one in stock. It is risky to disregard the words of the manufacturer's installation manuals. It's also disappointing that the manufacturers of this device did not craft a user-friendly design. The simplest thing to do is comply with the instructions. The simplest way to do this is acquire a component like this: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=FVTS10-15-ND Note that it can be mounted to some handy, out of the way surface on a long screw. The data sheet at: http://www.heiresistors.com/PDF/FVT_FST20%20spec.pdf tells us the hole through the middle of this device is 0.19" in diameter . . . The drill versus threaded sizes chart at: http://www.phy.mtu.edu/~suits/tapsizes.html says this is too small for a 10-32 screw but will be just fine for an 8-32. The resistor data sheet suggests we need one with 2" or so of over-all length. You'll be cranking a hard force down against a ceramic tube. Put a soft washer (some kind of rubber, plastic or even two layers of paper from the box that comes with a tube of toothpaste) between the end of the resistor and the mounting surface. Tighten the screw down to finger tight + 1 turn and spot the threads with some runny super-glue to keep it from drifting off that pressure setting. If your resistor comes with wires, clip them off. Attach lead wires for intercom power to the resistor's solder-tabs. Put double layer of heat-shrink over these joints for vibration support. This process has been used thousands of designs in various vehicular products including airplanes. Simple, lean, works as the manufacturer wishes and lasts a long time. BTW . . . the 15W rating is super conservative. The intercom may draw 1A peak current but the AVERAGE current will be much lower unless you're particularly fond of playing Wagner at 100dB in the headphones. Now, if you're REALLY wanting to make this more complicated, you can purchase one of B&C's DIM3-28 dimmers at: http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?10X358218#dim3-28 and instead of installing the dimmer potentiometer, you put the appropriate resistor between pins 1 and 3 to achieve a constant 14-volt output from the "dimmer". Bob . . . ________________________________ Message 9 _____________________________________ Time: 08:55:49 PM PST US From: "Peter Laurence" Subject: RE: AeroElectric-List: Fuse Block Locations Allen, Try MIH Industries. That's where I purchased mine about a year ago. http://home.earthlink.net/~dswartzendruber/ Peter Laurence -----Original Message----- My favorite so far! And where, pray tell, did you get that beautiful fuse block with cover? Surely must be automotive! Allen Fulmer RV7 Avionics and Electrical ------------------------------------------------------------------------------------- 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.