---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 11/01/13: 19 ---------------------------------------------------------- Today's Message Index: ---------------------- 0. 12:21 AM - PLEASE READ - Matronics Email List Fund Raiser During November! (Matt Dralle) 1. 05:06 AM - Re: Alternator without a Battery (Robert L. Nuckolls, III) 2. 05:13 AM - Re: Aviation intercom (Robert L. Nuckolls, III) 3. 05:31 AM - Re: A&P Student Battery/Starter Contactor Question (Robert L. Nuckolls, III) 4. 05:33 AM - Re: Aviation intercom (Harley) 5. 05:38 AM - Re: Contactors (Robert L. Nuckolls, III) 6. 05:38 AM - Re: Contactors (Robert L. Nuckolls, III) 7. 05:54 AM - Re: Aviation intercom (R. curtis) 8. 05:55 AM - Contactors (Robert L. Nuckolls, III) 9. 07:20 AM - Watts on resistors (Carlos Trigo) 10. 08:16 AM - Re: Watts on resistors (R. curtis) 11. 08:33 AM - Re: Watts on resistors (Henador Titzoff) 12. 08:40 AM - Re: Watts on resistors (Robert L. Nuckolls, III) 13. 08:42 AM - Re: Watts on resistors (Robert L. Nuckolls, III) 14. 08:48 AM - Re: Watts on resistors (Peter Pengilly) 15. 08:48 AM - Re: Watts on resistors (Tim Andres) 16. 10:25 AM - Re: Watts on resistors (Robert L. Nuckolls, III) 17. 10:34 AM - Re: Contactors (Sacha) 18. 10:45 AM - Re: Contactors (Sacha) ________________________________ Message 0 _____________________________________ Time: 12:21:55 AM PST US From: Matt Dralle Subject: AeroElectric-List: PLEASE READ - Matronics Email List Fund Raiser During November! Dear Listers, Each November I hold a PBS-like fund raiser to support the continued operation and upgrade of the Email List and Fourm Services at Matronics. 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Each one offers a unique and excellent aviation-related product line. I would like publicly to thank Andy, Bob, Corbin, George, and Jon their generous support of the Lists again this year!! Please make your List Contribution using any one of three secure methods including using a credit card, PayPal, or by personal check. All three methods afford you the opportunity to select one of this year's free gifts with a qualifying Contribution amount!! To make your Contribution, please visit the secure web site: http://www.matronics.com/contribution I would like to thank everyone in advance for their generous financial AND moral support over the years! Thank you! Matt Dralle Matronics Email List Administrator RV-4/RV-6/RV-8 Builder/Rebuilder/Pilot ________________________________ Message 1 _____________________________________ Time: 05:06:25 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Alternator without a Battery At 09:21 PM 10/30/2013, you wrote: Bob, It has taken days for me to respond because I couldn't get the website to respond to my enquiries and, consequently, I was unable to open your new drawing. Today I could! Thanks for your response. No problem. I started at Cessna last Monday and the IT Spirits have yet to honor me with a CAT5 portal to the outside world . . . So I've been 'disconnected' to some degree as well . . . You state that you wouldn't shut down a battery unless there is smoke in the cockpit and, in which case you would shut down the alternator as well. If a battery is shorting and drawing more and more current from the alternator, why wouldn't you disconnect it or do you consider this too unlikely to design against? First, how does such a fault become known to you? You would need a battery-specific ammeter combined with a bus voltage indicator combined with the skills to monitor and interpret those readings for signs of failure. You ask why two batteries? I'm reconsidering. If the battery can be disconnected and the engine continues to run on only the alternator, then one battery probably meets my design goals. Thanks for the question. A design goal for discussions on this List is to identify drivers of risk based on useful study and exploitation of the physics. As you suggested, I've looked at your new drawing, but I don't think it meets all my design goals. A shorted battery can't be disconnected. I'll continue to study it w.r.t my other design goals. Thanks. Have you identified any instance where a 'shorted battery' took a system down? A battery is like a house plant. Given attention tailored to its needs, it will thrive and perform with great predictability . . . and reliability. Instances of battery failure are generally driven by failure to track the battery's condition and to service or replace it when performance falls below limits. I've not heard the phrase "shorted battery" uttered or written over the course of my career where the battery was not first subjected to abuses of poor system architecture and/or poorly implemented operation and maintenance. We're encouraged to change oil, plugs, add magic potions, install engine analyzers, and read voraciously from every author that claims to offer words of wisdom for getting the most from an engine. Now the battery is becoming an integral component of the system that spins the prop. I suggest that it be treated with no less curiosity and respect for capabilities and limits than your engine. I will suggest that design goals for your system include crafting and implementation of an architecture and maintenance that recognizes the role of the battery and optimizes conditions for it to perform. Bob . . . ________________________________ Message 2 _____________________________________ Time: 05:13:27 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Aviation intercom At 07:30 PM 10/31/2013, you wrote: >Does anyone have the schematic or Manual for the WGA Model AIR-1177 >Aviation Intercom System? I am trying to figure out the input and >output jacks on the box. I intend to mount it in a panel along with >an isolation amp. > >Roger I've not been able to find this product on the 'net. Where did you find this critter? Bob . . . ________________________________ Message 3 _____________________________________ Time: 05:31:12 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: A&P Student Battery/Starter Contactor Question At 07:44 PM 10/31/2013, you wrote: Dear Bob, I just finished a very nice conversation with Bill Bainbridge at B and C Specialty Products, following through with a question to his company that I had sent through his website. I learned a great deal from Bill, though he's referred me to you for what was my initial question. Here was the original question: Hi Folks, I'm an A&P student at Miramar College in San Diego. I'm researching battery contactors and starter contactors, and haven't been able to figure out why battery contactors are negatively-controlled, and starter contactors are positively-controlled. Why can't both of them, (with slightly different wiring) both be, say, positively controlled? Is there some historical reason or some technical reason? I would so appreciate your expertise, as I heard you have a lot of expertise (from Lyle at Gibbs Repair Station here in San Diego). Thanks so much for your time. Regards. Bob, I've been reading through your FAQ's on contactors on your website--I'm learning much more than we learn in our A & P textbooks! However, I haven't quite been able to piece together the information for my answer. I think if I'm out in the bush wiring a plane together and I have two battery contactors and no starter contactor (as my instructor says... A & P Mechanics are the smartest people in the world, and they'll figure out a way to do something...:-)...) that's when I wonder why they are electrically wired differently. Hi Lisa, I don't know that there was any great debate for the realization of design goals beyond simplicity and convenience. Doing a pull-down circuit on a battery contactor is simpler. One could bring a wire off the hot side of a contactor into the cockpit mounted battery switch and back out to a pull-up terminal of a contactor coil . . . twice the wire and you need to fuse the hot end of the supply wire. I've seen starter contactors wired as a "pull to ground" control system, just no on airplanes. The legacy off-l-r-both-start key-switch could be wired to utilize a starter contactor with either pull-down or pull-up control. Power to control the starter contactor is already available from a bus in the cockpit so you don't have twice the wire . . . but you DO need circuit protection off the bus. It might have some roots in a system safety decision. A starter pull-down control line on a starter contactor is more likely to become faulted to ground and initiate unintended starter operation. A pull-up control line is less likely to get faulted to a source of power. The short answer to your question does not offer insights into any great thinking on the part of designers who adopted these conventions 100 years ago. Designers in those days were probably not into reliability studies of probability for hazardous failure. Bob . . . ________________________________ Message 4 _____________________________________ Time: 05:33:51 AM PST US From: Harley Subject: Re: AeroElectric-List: Aviation intercom Bob (and Roger)... I found the intercom on the maker's website, ( www.warrengregoire.com/aviation-intercoms.htm ) but no manuals or schematics there. However, there is contact information: * Warren Gregoire and Associates LLC* FOR PILOTS AND AIRCRAFT OWNERS 1933 Davis Street, Suite 276, San Leandro, CA 94577, USA HOURS* *7:00 am - 7:00 pm PST, 7 days a week/365 days a year _ _TELEPHONES* */*TOLL-FREE*/ *1-800-634-0094* - USA and Canada 510-633-9353 - All Other Countries 510-633-9355 - FAX INTERNET* *warrengregoire@hotmail.com - Questions? warrengregoire@hotmail.com - Sales Department Harley Dixon ----------------------------------------------------------------- On 11/1/2013 8:13 AM, Robert L. Nuckolls, III wrote: > At 07:30 PM 10/31/2013, you wrote: >> Does anyone have the schematic or Manual for the WGA Model >> AIR-1177 Aviation Intercom System? I am trying to figure out >> the input and output jacks on the box. I intend to mount it >> in a panel along with an isolation amp. >> >> Roger > > I've not been able to find this product on the 'net. > Where did you find this critter? > > > Bob . . . > > * > * ________________________________ Message 5 _____________________________________ Time: 05:38:15 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Contactors At 12:10 AM 11/1/2013, you wrote: > >I use automotive "cube" relays (one for the master relay, one for >alternator) rated at 70A. They are light and consume less than 300mA >each. Is there a reason not to use them? The only potential >drawback I'm aware of is that they can break the contact if subject >to violent shocks. But loosing panel power for a few milliseconds >doesn't seem such a big issue (the autopilot does reset but then in >such violent turbulence you might be hand flying the thing in any >case, and the GNS430 doesn't even notice any absence of power that >lasts that little). > >Are there other risks I am not considering here? This is a VFR only >machine and I'm a low time PPL so not the most experienced in these matters. The legacy battery contactor is tasked with carrying normal operating loads usually in the tens of amps but predicated on getting an engine started . . . loads of perhaps 200A. Hence the selection of contactors that seem unnecessarily oversized to the task. But the one device can do it all. Some of the designs we're considering DO add smaller relays which function as a mini-contactor to handle loads other than starting and/or battery recharging. Bob . . . ________________________________ Message 6 _____________________________________ Time: 05:38:59 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Contactors At 12:21 AM 11/1/2013, you wrote: >Sacha, >I have used one of these Bosch 70amp relays for the master in my >experimental Bonanza for the past 8 years - rock solid! I still use >the caveman relay for the starter. > >Bob Verwey >A35 ZU-DLW But you don't crank the engine through it do you? Bob . . . ________________________________ Message 7 _____________________________________ Time: 05:54:56 AM PST US From: "R. curtis" Subject: Re: AeroElectric-List: Aviation intercom Does anyone have the schematic or Manual for the WGA Model AIR-1177 Aviatio n Intercom System=3F I am trying to figure out the input and output jacks on the box. I intend to mount it in a panel along with an isolation amp. I've not been able to find this product on the 'net. Where did you find this critter=3F A Google search brings it right up: http://www.warrengregoire.com/aviation- intercoms.htm Roger -- Do you have a slow PC=3F Try a Free scan http://www.spamfighter.com/SLOW-PCfi ghter=3Fcid=sigen ________________________________ Message 8 _____________________________________ Time: 05:55:23 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Contactors From my newly acquired perch within the halls of Cessna Engineering I've discovered that the battery and starter contactors used on the single engine fleet have pretty much always been in the same style and ratings as the Cole-Hersee, RBM, Stancore, White-Rogers devices we've been discussing here on the List. Before the Great Shut-Down, Cessna purchased individual contactors for installation on the line. After the Great Resurrection, the contactors came to Cessna as part of a power distribution box mounting up to 4 such contactors. Battery, starter, alternator, ground- power. Of course, they're all 24 volt devices. During my earlier tenure at Cessna (64-69) the starter contactors were a low-duty cycle version of the battery contactor. They left something to be desired as SWITCHING devices for starter currents. I suspect that the modern starter contactors have exploited discoveries common to contemporary automotive starter contactors for small area, very high pressure contacts. http://tinyurl.com/96wy5mq Yes, there have been some serviceability issues managed by some modifications to the contact materials, springs, etc. etc. But the general configuration of the modern contactor has changed little since 1948. But in particular, there's no reason to believe that the modern encarnation of the 70 series device is any less suited to task as a battery contactor than it has been for many years. I dug up a 1960 copy of an Allied Electronics catalog hoping to discover the price of these devices back then. They don't appear in that catalog. Bob . . . ________________________________ Message 9 _____________________________________ Time: 07:20:42 AM PST US Subject: AeroElectric-List: Watts on resistors From: Carlos Trigo Bob and all The VP-X Pro installation manual recomends, in order to have Volt indication from the Aux Batt, to connect the + terminal to a certain pin in the box, trough a 1Kohm - 1W resistor. Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else today, can someone please explain if there is any problem if I use the 2W instead of 1W resistor. (Please don't answer indicating a source for 1W resistors...) Regards Carlos ________________________________ Message 10 ____________________________________ Time: 08:16:59 AM PST US From: "R. curtis" Subject: Re: AeroElectric-List: Watts on resistors > Problem is that I can only find 1Kohm - 2W resistor. So, to learn > something else today, can someone please explain if there is any problem > if I use the 2W instead of 1W resistor. The 2 watt resistor will work exactly the same in the circuit as a 1 watt. The only difference is that the 2 watt is somewhat larger with more surface area and can dissipate more heat without burning up. Roger -- Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen ________________________________ Message 11 ____________________________________ Time: 08:33:35 AM PST US From: Henador Titzoff Subject: Re: AeroElectric-List: Watts on resistors It should be no problem, Carlos, as long as you have enough room and the circuit isn't frequency sensitive. Wattage is the resistor's ability to dissipate heat, and the resistor is bigger as the wattage goes up. Henador Titzoff -------------------------------------------- On Fri, 11/1/13, Carlos Trigo wrote: Subject: AeroElectric-List: Watts on resistors To: "aeroelectric-list@matronics.com" Date: Friday, November 1, 2013, 7:21 AM --> AeroElectric-List message posted by: Carlos Trigo Bob and all The VP-X Pro installation manual recomends, in order to have Volt indication from the Aux Batt, to connect the + terminal to a certain pin in the box, trough a 1Kohm - 1W resistor. Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else today, can someone please explain if there is any problem if I use the 2W instead of 1W resistor. (Please don't answer indicating a source for 1W resistors...) Regards Carlos Lists This Month -- Some AWESOME FREE Gifts!) Raiser. Click on more about Gifts provided www.aeroelectric.com www.buildersbooks.com www.homebuilthelp.com www.mypilotstore.com www.mrrace.com -Matt Dralle, List Admin. AeroElectric-List Email Forum - - MATRONICS WEB FORUMS - ________________________________ Message 12 ____________________________________ Time: 08:40:41 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Watts on resistors At 09:21 AM 11/1/2013, you wrote: > >Bob and all > >The VP-X Pro installation manual recomends, in order to have Volt >indication from the Aux Batt, to connect the + terminal to a certain >pin in the box, trough a 1Kohm - 1W resistor. >Problem is that I can only find 1Kohm - 2W resistor. So, to learn >something else today, can someone please explain if there is any >problem if I use the 2W instead of 1W resistor. >(Please don't answer indicating a source for 1W resistors...) That's an easy one. The resistor is a substitute for a fuse. Further, it's called out as 1-watt for mechanical convenience and robustness. Examples: Some years back I suggested that the most valuable and often least accessible data point for diagnosing an alternator problem is to watch FIELD VOLTAGE behavior while putting an alternator through its paces. I published this little feature in Z-23 suggesting a permanently attached wire PROTECTED by a resistor leading from the alternator field to some handy point in the cockpit. Emacs! A fuse would be okay too. A 1/4 watt would work but 1/2 watt was mechanically more robust, 1w would have been better yet. So as long as you don't mind a larger 'lump' in your battery sense lead, a 2W resistor is okay as well. http://tinyurl.com/kyc6tq6 I think it was here on the List that I once suggested a tubular, 10-watt wire wound resistor with flag terminals as a suitable enclosure for a reed switch current sensor. Emacs! The 'jeep' was to put lead wires on the reed switch then epoxy into place down the center of the tubular resistor. Then wind an excitation coil around the center of the resistor over the reed. Calibrate closure current for the reed by adjusting coil turns. In this case, the actual value of the resistor wasn't critical . . . just needed to be high enough not to adversely affect current through the the coil. The resistor became a robust 'housing' for the current sense relay offering a convenient terminals to tie off ends of the coil. These are but two examples of many where the designer's 'sizing' of a component may not have obvious foundation in the original design goals for the part. Bob . . . ________________________________ Message 13 ____________________________________ Time: 08:42:28 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Watts on resistors > The VP-X Pro installation manual recomends, in order to have > Volt indication from the Aux Batt, to connect the + terminal > to a certain pin in the box, trough a 1Kohm - 1W resistor. Hmmm . . . I think Marc harvested that concept for sense wire protection off of Z-23. Bob . . . ________________________________ Message 14 ____________________________________ Time: 08:48:48 AM PST US From: Peter Pengilly Subject: Re: AeroElectric-List: Watts on resistors Hi Carlos, My view is 2W will be fine - it means that the resistor will cope with a higher voltage (45v) & so dissipate more energy. A 1W resistor will cope with 32v (theoretically). Peter On 01/11/2013 14:21, Carlos Trigo wrote: > > Bob and all > > The VP-X Pro installation manual recomends, in order to have Volt indication from the Aux Batt, to connect the + terminal to a certain pin in the box, trough a 1Kohm - 1W resistor. > Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else today, can someone please explain if there is any problem if I use the 2W instead of 1W resistor. > (Please don't answer indicating a source for 1W resistors...) > > Regards > Carlos > > ________________________________ Message 15 ____________________________________ Time: 08:48:58 AM PST US Subject: Re: AeroElectric-List: Watts on resistors From: Tim Andres So it sounds like they are using a resistor to protect the sensor wire from over current/unintentional ground instead of a fuse, is that the purpose here? Tim > On Nov 1, 2013, at 8:15 AM, "R. curtis" wrote: > > >> Problem is that I can only find 1Kohm - 2W resistor. So, to learn something else today, can someone please explain if there is any problem if I use the 2W instead of 1W resistor. > > The 2 watt resistor will work exactly the same in the circuit as a 1 watt. > The only difference is that the 2 watt is somewhat larger with more surface > area and can dissipate more heat without burning up. > > Roger > > -- > > Do you have a slow PC? Try a Free scan http://www.spamfighter.com/SLOW-PCfighter?cid=sigen > > > > > > ________________________________ Message 16 ____________________________________ Time: 10:25:37 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Watts on resistors At 10:48 AM 11/1/2013, you wrote: > >So it sounds like they are using a resistor to protect the sensor >wire from over current/unintentional ground instead of a fuse, is >that the purpose here? >Tim Exactly. The input impedance to the instrumentation system is either sufficiently large that added 1K of resistance is insignificant . . . or is a calculated part of the input voltage divider. Bob . . . ________________________________ Message 17 ____________________________________ Time: 10:34:23 AM PST US Subject: Re: AeroElectric-List: Contactors From: Sacha >>> Sacha, >>> I have used one of these Bosch 70amp relays for the master in my experimental Bonanza for the past 8 years - rock solid! I still use the caveman relay for the starter. >>> >>> Bob Verwey >>> A35 ZU-DLW >> Thanks Bob V for the validation. >> But you don't crank the engine through it do you? No, the starter contactor is not the automotive type. ________________________________ Message 18 ____________________________________ Time: 10:45:31 AM PST US Subject: Re: AeroElectric-List: Contactors From: Sacha On Nov 1, 2013, at 13:37, "Robert L. Nuckolls, III" wrote: > > At 12:10 AM 11/1/2013, you wrote: >> >> I use automotive "cube" relays (one for the master relay, one for alternator) rated at 70A. They are light and consume less than 300mA each. Is there a reason not to use them? The only potential drawback I'm aware of is that they can break the contact if subject to violent shocks. But loosing panel power for a few milliseconds doesn't seem such a big issue (the autopilot does reset but then in such violent turbulence you might be hand flying the thing in any case, and the GNS430 doesn't even notice any absence of power that lasts that little). >> >> Are there other risks I am not considering here? This is a VFR only machine and I'm a low time PPL so not the most experienced in these matters. > > The legacy battery contactor is tasked with > carrying normal operating loads usually in > the tens of amps but predicated on getting an > engine started . . . loads of perhaps 200A. Ah. Ok now I understand your previous question. In my case the fat wire to the starter contactor is always hot. The master just activates the coil circuit. I now know this is against conventional design where master OFF is supposed to correspond to max darkness. In my case the total length of fat (positive) wire is approx 50cm (20"): battery to starter contactor to starter motor. ------------------------------------------------------------------------------------- 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.