---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 11/03/10: 21 ---------------------------------------------------------- Today's Message Index: ---------------------- 0. 12:21 AM - November List Fund Raiser (Matt Dralle) 1. 06:12 AM - Re: Battery contactor versus circuit breaker (Noel Loveys) 2. 06:29 AM - Re: Battery contactor versus circuit breaker (Eric M. Jones) 3. 07:08 AM - Re: Z-16 (user9253) 4. 07:59 AM - Re: VOTE! (rampil) 5. 08:06 AM - Re: Re: Z-16 (Robert L. Nuckolls, III) 6. 08:37 AM - Re: Battery contactor versus circuit breaker (Robert L. Nuckolls, III) 7. 08:42 AM - Re: Re: Z-16 (Robert L. Nuckolls, III) 8. 08:48 AM - Re: Re: Z-16 (Dan Billingsley) 9. 10:08 AM - Toggle Switch Failure (reprise) (Vern Little) 10. 10:39 AM - Re: Toggle Switch Failure (reprise) (B Tomm) 11. 11:05 AM - Re: Re: Z-16 (tim2542@sbcglobal.net) 12. 11:09 AM - Re: Toggle Switch Failure (reprise) (David E. Nelson) 13. 11:51 AM - Re: Toggle Switch Failure (reprise) (Vern Little) 14. 11:51 AM - Re: Toggle Switch Failure (reprise) (Vern Little) 15. 12:07 PM - Re: Toggle Switch Failure (reprise) (tim2542@sbcglobal.net) 16. 02:09 PM - Re: AeroElectric-List Digest: 7 Msgs - 11/01/10 (Fergus Kyle) 17. 03:33 PM - Re: AeroElectric-List Digest: 7 Msgs - 11/01/10 (rparigoris) 18. 05:46 PM - Re: Re: Z-16 Diode relays (paul wilson) 19. 07:02 PM - Re: Re: Z-16 Diode relays (Tony Babb) 20. 08:45 PM - Re: Re: Z-16 Diode relays (Bob Meyers) ________________________________ Message 0 _____________________________________ Time: 12:21:04 AM PST US From: Matt Dralle Subject: AeroElectric-List: November List Fund Raiser There is an automatic "squelch button" of sorts for the Fund Raiser messages. Here's how it works... As soon as a List member makes a Contribution through the Matronics Fund Raiser web site, they will instantly cease to receive these Fund Raiser messages for the rest of the month! Its just that simple. I really do appreciate each and every one of your individual Contributions to support the Lists. It is your support that enables me to upgrade the hardware and software that are required to run a List Site such as this one. It also goes to pay for the commercial-grade Internet connection and to pay the huge electric bill to keep the computer gear running and the air conditioner powered on. I run all of the Matronics Email List and Forums sites here locally which allows me to control and monitor every aspect of the system for the utmost in reliably and performance. Your personal Contribution matters because, when combined with other Listers such as yourself, it pays the bills to keep this site up and running. I accept exactly ZERO advertising dollars for the Matronics Lists sites. I can't stand the pop-up ads and all other commercials that are so prevalent on the Internet these days and I particularly don't want to have it on my Email List sites. If you appreciate the ad-free, grass-roots, down-home feel of the Matronics Email Lists, please make a Contribution to keep it that way!! http://www.matronics.com/contribution Thank you! Matt Dralle Matronics Email List Administrator [Note that there are certain circumstances where you might still see a Contribution related message. For example, if someone replies to one of the messages, when using the List Browse feature, or when accessing List message via the Forum. The system keys on the given email address and since most of these are anonymous public access methods, there is no simple way to filter them.] ________________________________ Message 1 _____________________________________ Time: 06:12:03 AM PST US From: "Noel Loveys" Subject: RE: AeroElectric-List: Battery contactor versus circuit breaker Without seeing your schematic it sounds like the main cable coming from your battery pack has no protection on it until it gets to the panel where the circuit breaker is. Protection of the main battery cable is the reason that contactors are installed as close to the battery as possible, especially in installations where the battery is in the back of the plane. That includes the starter solenoid and master relay. Noel -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of mmayfield Sent: November 2, 2010 8:27 PM Subject: AeroElectric-List: Battery contactor versus circuit breaker OK, so the aircraft we're talking about has a very simple electrical system. Day VFR only, a comm, a transponder, a few miscellaneous widgets like boost pump, smoke pump, engine monitor, a couple of solenoid valves, and the engine is the venerable M14P which is an air start motor. So the battery is also correspondingly small, and recharged by the B&C SK10 alternator. The traditional basic electrical schematic has an avionics master but I'm discarding this because, well, I just can't see why it is needed at all for this setup. Any issues there? This diagram is also drawn with no battery contactor, but a main battery circuit breaker instead, and the master switch is 14AWG wire in one side and out the other to the bus, I believe. How does this rate compared to using a battery contactor instead? I do recall Bob talking of this being a bit of an unconventional layout (regarding a B&C wiring diagram a while back). Would it be better to specify a battery contactor in a conventional arrangement, or for this system would it not matter too much? Mike Read this topic online here: http://forums.matronics.com/viewtopic.php?p=317913#317913 ________________________________ Message 2 _____________________________________ Time: 06:29:11 AM PST US Subject: AeroElectric-List: Re: Battery contactor versus circuit breaker From: "Eric M. Jones" Mike, Be aware that a battery disconnection device that can be operated with one hand is an FAA requirement. A battery contactor is an easy way to achieve this, but you can do it with a big switch too. I have been recommending a race-car switch for battery disconnection. See "Flaming River" battery switch. Similar switches can be had from Harbor Freight. Removing the handle can offer anti-theft protection too. -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=318024#318024 ________________________________ Message 3 _____________________________________ Time: 07:08:49 AM PST US Subject: AeroElectric-List: Re: Z-16 From: "user9253" Hi Dan, I am not familiar with the S704-1 relay. But since nobody else answered, I will give it a shot. Polarity of the coil does not matter for most relays. If a relay has a built in diode, then polarity will matter. You could test the coil with an ohmmeter to see if the coil is short circuited with one polarity and not the other. Or you could put a small lamp in series with the relay. If the lamp gets brighter with one polarity compared to the opposite polarity, then there is a built in diode and the correct polarity is when the lamp is dim. Or you could power up the relay using a power supply with built in short circuit protection and see what happens. Or you could call B&C and ask them. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=318027#318027 ________________________________ Message 4 _____________________________________ Time: 07:59:26 AM PST US Subject: AeroElectric-List: Re: VOTE! From: "rampil" Major Daley (the elder) said: Vote Early, Vote Often! -------- Ira N224XS Read this topic online here: http://forums.matronics.com/viewtopic.php?p=318033#318033 ________________________________ Message 5 _____________________________________ Time: 08:06:50 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Z-16 At 09:05 AM 11/3/2010, you wrote: > >Hi Dan, >I am not familiar with the S704-1 relay. But since nobody else >answered, I will give it a shot. Polarity of the coil does not >matter for most relays. If a relay has a built in diode, then >polarity will matter. You could test the coil with an ohmmeter to >see if the coil is short circuited with one polarity and not the >other. Or you could put a small lamp in series with the relay. If >the lamp gets brighter with one polarity compared to the opposite >polarity, then there is a built in diode and the correct polarity is >when the lamp is dim. Or you could power up the relay using a power >supply with built in short circuit protection and see what >happens. Or you could call B&C and ask them. Good put. I'm aware of no commercial-off-the-shelf relays with built in diodes and only a few contactors with such devices already installed. If they DO feature internally wired diodes, the coil terminal polarity will be marked and the device will probably have some symbolism or text notification of the feature. The "S704" is a catalog number for a "T91" style SPDT relay first defined by Potter-Brumfield as I recall . . . and later 'cloned' by many others as popularity of this device soared. Emacs! But it's nothing special. Any 12v, 30A, DPDT relay will do the same job . . . including this device from Radio Shack Emacs! Catalog #275-226. Many of the BigBox auto parts stores sell similar devices in peg-racked blister- paks. It might be called a "headlight relay". But its a sure bet than none will feature built in diodes. Here's an exemplar part from the AutoZone website: http://tinyurl.com/24gobxs Interestingly enough, AutoZone stocks a pre-terminated diode assembly that can be added to this or similar relays: http://tinyurl.com/2cqrk4q Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 6 _____________________________________ Time: 08:37:29 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Battery contactor versus circuit breaker At 08:08 AM 11/3/2010, you wrote: Without seeing your schematic it sounds like the main cable coming from your battery pack has no protection on it until it gets to the panel where the circuit breaker is. Protection of the main battery cable is the reason that contactors are installed as close to the battery as possible, especially in installations where the battery is in the back of the plane. That includes the starter solenoid and master relay. I'll offer the following expansion of the idea behind local battery disconnect. It's not so much for "protection" of any wires as for reduction in probability of post-crash fire. A powered up electrical system could warm up your day considerably without damaging a single wire. A engineer friend of mine at Hawker-Beech used to investigate accidents involving our products. He once shared an anecdotal observation suggesting that if the airplane caught fire after the crash, the battery was most likely still in the airframe. If it didn't burn, he expected to find the battery tossed into the woods somewhere. Obviously not scientific but a valid recognition of the energy that can be released when a battery is discharged into the bent-metal products of a crash. Having a pre-crash procedure that isolates the battery from as much of ship's wiring as practical goes a long way toward reducing after-crash hazard. Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 7 _____________________________________ Time: 08:42:34 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Z-16 > Interestingly enough, AutoZone stocks a pre-terminated > diode assembly that can be added to this or similar > relays: > >http://tinyurl.com/2cqrk4q Whew!!!! just noted that this part sells for about $10. Go get your own 1N5402, 75-cent critters from R-S . . . Emacs! Bob . . . --------------------------------------- ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) --------------------------------------- ________________________________ Message 8 _____________________________________ Time: 08:48:12 AM PST US From: Dan Billingsley Subject: Re: AeroElectric-List: Re: Z-16 Joe and Bob, Thank you for your reply...I found it interesting that the relay had little to no markings. It came with a sheet that identified a couple of contacts, yet left the coil to one's imagination. This led me to believe that polarity is not an issue. Again, thanks Joe for the reply and practicle things to try to make determinations. Best wishes, Dan ----- Original Message ---- From: user9253 Sent: Wed, November 3, 2010 7:05:41 AM Subject: AeroElectric-List: Re: Z-16 Hi Dan, I am not familiar with the S704-1 relay. But since nobody else answered, I will give it a shot. Polarity of the coil does not matter for most relays. If a relay has a built in diode, then polarity will matter. You could test the coil with an ohmmeter to see if the coil is short circuited with one polarity and not the other. Or you could put a small lamp in series with the relay. If the lamp gets brighter with one polarity compared to the opposite polarity, then there is a built in diode and the correct polarity is when the lamp is dim. Or you could power up the relay using a power supply with built in short circuit protection and see what happens. Or you could call B&C and ask them. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=318027#318027 ________________________________ Message 9 _____________________________________ Time: 10:08:59 AM PST US From: "Vern Little" Subject: AeroElectric-List: Toggle Switch Failure (reprise) My (final) conclusion on toggle switch failures in my RV-9A. In a recent Transport Canada Aviation Safety Letter, there is an article that is relevant to the long debate we had a few years ago about the failure of toggle switches (specifically Carling brand) in the strobe, landing and taxi light circuits of our aircraft. The article is here: http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf The summary is this: Cessna has issued a mandatory service bulletin to replace all subject switches used in the landing light as well as the taxi light and rotating beacon circuits in the 100-, 200- and 300- series. The FAA issued an SAIB to this effect. The root cause is that the switches used were not suitable to the applications. Surge currents are many times (8x) the nominal currents for lighting loads, well outside the switch ratings. Also, the switches used did not have DC ratings. During the aeroelectric debate and Bob`s research of the Carling switch failures, we found evidence of manufacturing problems, however, overstressing the switches may be in fact the causal link in the failure chain. I used inrush current limiters on my landing light circuits which helps. My strobe switches did not use the limiters and failed just short of a smoke/fire incident. These switches have no specific DC rating, although common use is to follow the 115VAC rated current. Therefore, my next aircraft (HR-II) is not using switches to carry heavy loads. Instead, it will be using DC-rated relays (with up to 70A DC rating for resistive loads). These should be adequate for most loads. The relays are controlled with low-current switches (with gold/silver contacts). Thanks, Vern ________________________________ Message 10 ____________________________________ Time: 10:39:29 AM PST US From: "B Tomm" Subject: RE: AeroElectric-List: Toggle Switch Failure (reprise) Thanks for the follow-up on this issue Vern. I am just now preparing to install toggle switches and also have the Carlings. I am planning to use relays for the heavy loads but now am wondering if the 20 amp relays that B and C sells will be up to the task, (if in fact inrush is 8X as you say). Would the inrush limiters limit it to say 2X or less and if so where does one buy them? Bevan Abbotsford RV7A wiring _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern Little Sent: Wednesday, November 03, 2010 10:04 AM Subject: AeroElectric-List: Toggle Switch Failure (reprise) My (final) conclusion on toggle switch failures in my RV-9A. In a recent Transport Canada Aviation Safety Letter, there is an article that is relevant to the long debate we had a few years ago about the failure of toggle switches (specifically Carling brand) in the strobe, landing and taxi light circuits of our aircraft. The article is here: http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf The summary is this: Cessna has issued a mandatory service bulletin to replace all subject switches used in the landing light as well as the taxi light and rotating beacon circuits in the 100-, 200- and 300- series. The FAA issued an SAIB to this effect. The root cause is that the switches used were not suitable to the applications. Surge currents are many times (8x) the nominal currents for lighting loads, well outside the switch ratings. Also, the switches used did not have DC ratings. During the aeroelectric debate and Bob`s research of the Carling switch failures, we found evidence of manufacturing problems, however, overstressing the switches may be in fact the causal link in the failure chain. I used inrush current limiters on my landing light circuits which helps. My strobe switches did not use the limiters and failed just short of a smoke/fire incident. These switches have no specific DC rating, although common use is to follow the 115VAC rated current. Therefore, my next aircraft (HR-II) is not using switches to carry heavy loads. Instead, it will be using DC-rated relays (with up to 70A DC rating for resistive loads). These should be adequate for most loads. The relays are controlled with low-current switches (with gold/silver contacts). Thanks, Vern ________________________________ Message 11 ____________________________________ Time: 11:05:44 AM PST US From: tim2542@sbcglobal.net Subject: Re: AeroElectric-List: Re: Z-16 I bought relays from NAPA, no diode but they do have resistors in the coil c ircuit. I don't have the part number with me but can get it. Tim Andres Sent from my iPhone On Nov 3, 2010, at 8:04 AM, "Robert L. Nuckolls, III" wrote: > At 09:05 AM 11/3/2010, you wrote: m> >> >> Hi Dan, >> I am not familiar with the S704-1 relay. But since nobody else answered, I will give it a shot. Polarity of the coil does not matter for most relay s. If a relay has a built in diode, then polarity will matter. You could t est the coil with an ohmmeter to see if the coil is short circuited with one polarity and not the other. Or you could put a small lamp in series with t he relay. If the lamp gets brighter with one polarity compared to the oppos ite polarity, then there is a built in diode and the correct polarity is whe n the lamp is dim. Or you could power up the relay using a power supply wit h built in short circuit protection and see what happens. Or you could call B&C and ask them. > > Good put. I'm aware of no commercial-off-the-shelf relays > with built in diodes and only a few contactors with such > devices already installed. If they DO feature internally > wired diodes, the coil terminal polarity will be marked > and the device will probably have some symbolism or > text notification of the feature. > > The "S704" is a catalog number for a "T91" style > SPDT relay first defined by Potter-Brumfield as > I recall . . . and later 'cloned' by many others > as popularity of this device soared. > > <263881f.jpg> > > But it's nothing special. Any 12v, 30A, DPDT > relay will do the same job . . . including > this device from Radio Shack > > <263887d.jpg> > > Catalog #275-226. Many of the BigBox auto parts > stores sell similar devices in peg-racked blister- > paks. It might be called a "headlight relay". > But its a sure bet than none will feature built > in diodes. Here's an exemplar part from the > AutoZone website: > > http://tinyurl.com/24gobxs > > Interestingly enough, AutoZone stocks a pre-terminated > diode assembly that can be added to this or similar > relays: > > http://tinyurl.com/2cqrk4q > > > > Bob . . . > > --------------------------------------- > ( . . . a long habit of not thinking ) > ( a thing wrong, gives it a superficial ) > ( appearance of being right . . . ) > ( ) > ( -Thomas Paine 1776- ) > --------------------------------------- > ________________________________ Message 12 ____________________________________ Time: 11:09:49 AM PST US From: "David E. Nelson" Subject: Re: AeroElectric-List: Toggle Switch Failure (reprise) Hi Vern, I was just thinking about this thread the other week while hooking up my strobe power-supply. The unit is a Nova XPAK-604 (IIRC) and I noticed that in the supplied wiring diagram that they tied the supply lead to the power source w/o any switches. The unit's operation is then turned on/off by a control signal via a small guage wire. I don't recall anybody else mentioning this so I'm bringing it up because I think it may offer a viable alternative for others that are using this unit. The install guide is here: http://www.strobesnmore.com/nova-x-pak-strobe-power-supplies.html Regards, /\/elson ~~ Lately my memory seems to be like a steel trap .... without any spring. ~~ On Wed, 3 Nov 2010, Vern Little wrote: > My (final) conclusion on toggle switch failures in my RV-9A. > > In a recent Transport Canada Aviation Safety Letter, there is an article that is relevant to the long debate we had a few years ago about the failure of toggle switches (specifically Carling > brand) in the strobe, landing and taxi light circuits of our aircraft. > > The article is here: http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf > > The summary is this: Cessna has issued a mandatory service bulletin to replace all subject switches used in the landing light as well as the taxi light and rotating beacon circuits in the > 100-, 200- and 300- series. The FAA issued an SAIB to this effect. > > The root cause is that the switches used were not suitable to the applications. Surge currents are many times (8x) the nominal currents for lighting loads, well outside the switch ratings. > Also, the switches used did not have DC ratings. > > During the aeroelectric debate and Bob`s research of the Carling switch failures, we found evidence of manufacturing problems, however, overstressing the switches may be in fact the causal > link in the failure chain. I used inrush current limiters on my landing light circuits which helps. My strobe switches did not use the limiters and failed just short of a smoke/fire > incident. These switches have no specific DC rating, although common use is to follow the 115VAC rated current. > > Therefore, my next aircraft (HR-II) is not using switches to carry heavy loads. Instead, it will be using DC-rated relays (with up to 70A DC rating for resistive loads). These should be > adequate for most loads. The relays are controlled with low-current switches (with gold/silver contacts). > > Thanks, > Vern ________________________________ Message 13 ____________________________________ Time: 11:51:38 AM PST US From: "Vern Little" Subject: Re: AeroElectric-List: Toggle Switch Failure (reprise) Relays are cheap, even the 70A ones. They are mostly pin-compatible with the lower-rated ones. Both the relays and the limiters are available at Digikey. Search "automotive relay" and "inrush current limiter". I tend to use parts from Digikey, even if available at the local Tire and Hockey shop because of the traceability and datasheet availability. Vern From: B Tomm Sent: Wednesday, November 03, 2010 10:36 AM Subject: RE: AeroElectric-List: Toggle Switch Failure (reprise) Thanks for the follow-up on this issue Vern. I am just now preparing to install toggle switches and also have the Carlings. I am planning to use relays for the heavy loads but now am wondering if the 20 amp relays that B and C sells will be up to the task, (if in fact inrush is 8X as you say). Would the inrush limiters limit it to say 2X or less and if so where does one buy them? Bevan Abbotsford RV7A wiring ------------------------------------------------------------------------- ------- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Vern Little Sent: Wednesday, November 03, 2010 10:04 AM Subject: AeroElectric-List: Toggle Switch Failure (reprise) My (final) conclusion on toggle switch failures in my RV-9A. In a recent Transport Canada Aviation Safety Letter, there is an article that is relevant to the long debate we had a few years ago about the failure of toggle switches (specifically Carling brand) in the strobe, landing and taxi light circuits of our aircraft. The article is here: http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf The summary is this: Cessna has issued a mandatory service bulletin to replace all subject switches used in the landing light as well as the taxi light and rotating beacon circuits in the 100-, 200- and 300- series. The FAA issued an SAIB to this effect. The root cause is that the switches used were not suitable to the applications. Surge currents are many times (8x) the nominal currents for lighting loads, well outside the switch ratings. Also, the switches used did not have DC ratings. During the aeroelectric debate and Bob`s research of the Carling switch failures, we found evidence of manufacturing problems, however, overstressing the switches may be in fact the causal link in the failure chain. I used inrush current limiters on my landing light circuits which helps. My strobe switches did not use the limiters and failed just short of a smoke/fire incident. These switches have no specific DC rating, although common use is to follow the 115VAC rated current. Therefore, my next aircraft (HR-II) is not using switches to carry heavy loads. Instead, it will be using DC-rated relays (with up to 70A DC rating for resistive loads). These should be adequate for most loads. The relays are controlled with low-current switches (with gold/silver contacts). Thanks, Vern href="http://www.aeroelectric.com">www.aeroelectric.com href="http://www.buildersbooks.com">www.buildersbooks.com href="http://www.homebuilthelp.com">www.homebuilthelp.com href="http://www.matronics.com/contribution">http://www.matronics.com/c href="http://www.matronics.com/Navigator?AeroElectric-List">http://www. matronics.com/Navigator?AeroElectric-List href="http://forums.matronics.com">http://forums.matronics.com ------------------------------------------------------------------------- ------- Checked by AVG - www.avg.com 08:36:00 ________________________________ Message 14 ____________________________________ Time: 11:51:46 AM PST US From: "Vern Little" Subject: Re: AeroElectric-List: Toggle Switch Failure (reprise) Thanks for the information. It seems that this is a viable alternative although I hate being able to shut down a power source in the event of a fire. A pullable breaker would be a good answer to that. Vern -------------------------------------------------- From: "David E. Nelson" Sent: Wednesday, November 03, 2010 11:05 AM Subject: Re: AeroElectric-List: Toggle Switch Failure (reprise) > > > > Hi Vern, > > I was just thinking about this thread the other week while hooking up my > strobe > power-supply. The unit is a Nova XPAK-604 (IIRC) and I noticed that in > the > supplied wiring diagram that they tied the supply lead to the power source > w/o > any switches. The unit's operation is then turned on/off by a control > signal > via a small guage wire. > > I don't recall anybody else mentioning this so I'm bringing it up because > I > think it may offer a viable alternative for others that are using this > unit. > > The install guide is here: > > http://www.strobesnmore.com/nova-x-pak-strobe-power-supplies.html > > Regards, > /\/elson > > > ~~ Lately my memory seems to be like a steel trap .... without any > spring. ~~ > > On Wed, 3 Nov 2010, Vern Little wrote: > >> My (final) conclusion on toggle switch failures in my RV-9A. >> >> In a recent Transport Canada Aviation Safety Letter, there is an article >> that is relevant to the long debate we had a few years ago about the >> failure of toggle switches (specifically Carling >> brand) in the strobe, landing and taxi light circuits of our aircraft. >> >> The article is here: >> http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf >> >> The summary is this: Cessna has issued a mandatory service bulletin to >> replace all subject switches used in the landing light as well as the >> taxi light and rotating beacon circuits in the >> 100-, 200- and 300- series. The FAA issued an SAIB to this effect. >> >> The root cause is that the switches used were not suitable to the >> applications. Surge currents are many times (8x) the nominal currents >> for lighting loads, well outside the switch ratings. >> Also, the switches used did not have DC ratings. >> >> During the aeroelectric debate and Bob`s research of the Carling switch >> failures, we found evidence of manufacturing problems, however, >> overstressing the switches may be in fact the causal >> link in the failure chain. I used inrush current limiters on my landing >> light circuits which helps. My strobe switches did not use the limiters >> and failed just short of a smoke/fire >> incident. These switches have no specific DC rating, although common use >> is to follow the 115VAC rated current. >> >> Therefore, my next aircraft (HR-II) is not using switches to carry heavy >> loads. Instead, it will be using DC-rated relays (with up to 70A DC >> rating for resistive loads). These should be >> adequate for most loads. The relays are controlled with low-current >> switches (with gold/silver contacts). >> >> Thanks, >> Vern > > > > Checked by AVG - www.avg.com > 08:36:00 > ________________________________ Message 15 ____________________________________ Time: 12:07:42 PM PST US From: tim2542@sbcglobal.net Subject: Re: AeroElectric-List: Toggle Switch Failure (reprise) Just did this last week myself! If you note they still require 18AWG wire as as minimum for the control lead, which made me think it must have some current on it. I used a relay to avoid having both leads go all the way forward and then back. Tim Andres Sent from my iPhone On Nov 3, 2010, at 11:05 AM, "David E. Nelson" wrote: > > > Hi Vern, > > I was just thinking about this thread the other week while hooking up my strobe power-supply. The unit is a Nova XPAK-604 (IIRC) and I noticed that in the supplied wiring diagram that they tied the supply lead to the power source w/o any switches. The unit's operation is then turned on/off by a control signal via a small guage wire. > > I don't recall anybody else mentioning this so I'm bringing it up because I think it may offer a viable alternative for others that are using this unit. > > The install guide is here: > > http://www.strobesnmore.com/nova-x-pak-strobe-power-supplies.html > > Regards, > /\/elson > > > ~~ Lately my memory seems to be like a steel trap .... without any spring. ~~ > > On Wed, 3 Nov 2010, Vern Little wrote: > >> My (final) conclusion on toggle switch failures in my RV-9A. >> In a recent Transport Canada Aviation Safety Letter, there is an article that is relevant to the long debate we had a few years ago about the failure of toggle switches (specifically Carling >> brand) in the strobe, landing and taxi light circuits of our aircraft. >> The article is here: http://www.tc.gc.ca/media/documents/ca-publications/tp185e_4_2010.pdf >> The summary is this: Cessna has issued a mandatory service bulletin to replace all subject switches used in the landing light as well as the taxi light and rotating beacon circuits in the >> 100-, 200- and 300- series. The FAA issued an SAIB to this effect. >> The root cause is that the switches used were not suitable to the applications. Surge currents are many times (8x) the nominal currents for lighting loads, well outside the switch ratings. Also, the switches used did not have DC ratings. >> During the aeroelectric debate and Bob`s research of the Carling switch failures, we found evidence of manufacturing problems, however, overstressing the switches may be in fact the causal >> link in the failure chain. I used inrush current limiters on my landing light circuits which helps. My strobe switches did not use the limiters and failed just short of a smoke/fire >> incident. These switches have no specific DC rating, although common use is to follow the 115VAC rated current. >> Therefore, my next aircraft (HR-II) is not using switches to carry heavy loads. Instead, it will be using DC-rated relays (with up to 70A DC rating for resistive loads). These should be >> adequate for most loads. The relays are controlled with low-current switches (with gold/silver contacts). >> Thanks, >> Vern > > > > ________________________________ Message 16 ____________________________________ Time: 02:09:21 PM PST US From: Fergus Kyle Subject: AeroElectric-List: RE: AeroElectric-List Digest: 7 Msgs - 11/01/10 Time: 03:50:43 PM PST US Subject: AeroElectric-List: LED strips for cabin light From: James Kilford Gents, I've been pondering for a while what to do about an inexpensive, neat cabin light for my Jodel project. I thought LEDs were the way to go, and instead of fabricating something, bought something like this: http://cgi.ebay.co.uk/24-LED-White-Flexible-Strip-Waterproof-Car-Light-Bulb- /160500858701#ht_3067wt_1066 It runs straight off the bus, is nice and bright, and was easy enough to mount. It's set into a slot in a piece of thin ply, with some spruce stiffeners each side of the slot, then the ply was covered with headlining material. It fits really well in the cabin roof. Picture attached. Forgive the poor quality, but hopefully you can make out what's going on. James James: My only question is : What the current draw for my poor old Ducati? No one ever seems to say..... Cheers Ferg ________________________________ Message 17 ____________________________________ Time: 03:33:55 PM PST US Subject: AeroElectric-List: Re: AeroElectric-List Digest: 7 Msgs - 11/01/10 From: "rparigoris" Hi Ferg "My only question is : What the current draw for my poor old Ducati? No one ever seems to say....." Someone gave me a partial string of LEDs in white that looks similar to what you referenced. I have been mutilating the sealed string to retrieve the individual LEDs that seem to be about the right color temp, size and brightness for several panel lighting applications. Anyway the ones I have have 3 LEDs in series with a resistor (intended to run off of 12 volts). The 3 series LEDs draw 19 mAs when running off my Odyssey 545. Thus on my string 24 would be drawing 152mAs or .152 amps. I fooled with bumping up to 20, 25, 30 and 35 mAs, not much of an increase in brightness. Ron Parigoris Read this topic online here: http://forums.matronics.com/viewtopic.php?p=318081#318081 ________________________________ Message 18 ____________________________________ Time: 05:46:42 PM PST US From: paul wilson Subject: Re: AeroElectric-List: Re: Z-16 Diode relays Bob, mid 90s vintage Ford relays all have the internal diode. When getting a replacement at the auto store I just look at the diagram on the thing. Most of the time they try to sell me the cheaper one with no diode. Then I just ask for the more expensive one and shure enough they always have the diode. There are 4 or 5 of them and they are all the same part number. NAPA is a good source, but not RS. They are the traditional 30a things just like we are all famiuliar with and fit a 1/4" female faston. Comfort is having spares Paul ________________________________ Message 19 ____________________________________ Time: 07:02:30 PM PST US From: "Tony Babb" Subject: RE: AeroElectric-List: Re: Z-16 Diode relays I know the answer must be blindingly obvous but it escapes me. Why have a diode in the first place, doesn't the relay close regardless of which way the current is flowing? Tony Velocity SEFG 62% done, 78% to go www.alejandra.net/velocity -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of paul wilson Sent: Wednesday, November 03, 2010 5:20 PM Subject: Re: AeroElectric-List: Re: Z-16 Diode relays Bob, mid 90s vintage Ford relays all have the internal diode. When getting a replacement at the auto store I just look at the diagram on the thing. Most of the time they try to sell me the cheaper one with no diode. Then I just ask for the more expensive one and shure enough they always have the diode. There are 4 or 5 of them and they are all the same part number. NAPA is a good source, but not RS. They are the traditional 30a things just like we are all famiuliar with and fit a 1/4" female faston. Comfort is having spares Paul ________________________________ Message 20 ____________________________________ Time: 08:45:51 PM PST US From: Bob Meyers Subject: Re: AeroElectric-List: Re: Z-16 Diode relays Voltage spike suppression. Bob posted a document a few weeks ago about the how and why of spike suppression. Here is the link. http://tinyurl.com/25wjo7w Bob Meyers Flight Testing Sonex N982SX Web Site Index http://N982SX.com On Nov 3, 2010, at 8:58 PM, Tony Babb wrote: > > > > I know the answer must be blindingly obvous but it escapes me. Why > have a > diode in the first place, doesn't the relay close regardless of > which way > the current is flowing? > > Tony > Velocity SEFG 62% done, 78% to go > www.alejandra.net/velocity > > -----Original Message----- > From: owner-aeroelectric-list-server@matronics.com > [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of > paul > wilson > Sent: Wednesday, November 03, 2010 5:20 PM > To: aeroelectric-list@matronics.com > Subject: Re: AeroElectric-List: Re: Z-16 Diode relays > > > > Bob, mid 90s vintage Ford relays all have the internal diode. When > getting a replacement at the auto store I just look at the diagram on > the thing. Most of the time they try to sell me the cheaper one with > no diode. Then I just ask for the more expensive one and shure enough > they always have the diode. There are 4 or 5 of them and they are all > the same part number. NAPA is a good source, but not RS. They are the > traditional 30a things just like we are all famiuliar with and fit a > 1/4" female faston. > Comfort is having spares > > Paul > > ------------------------------------------------------------------------------------- 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.