---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Thu 11/09/06: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:42 AM - Re: Transorbs and Lightning (Robert L. Nuckolls, III) 2. 05:49 AM - Re: Stacked 14v systems for 28v (Robert L. Nuckolls, III) 3. 06:12 AM - Re: Slick mag P-lead ground wire (Mike Lehman) 4. 06:42 AM - Re: Re: Slick mag P-lead ground wire (Robert L. Nuckolls, III) 5. 06:47 AM - Re: Re: Stacked 14v systems for 28v (Deems Davis) 6. 08:45 AM - Reasonable qualification for flight hardware? () 7. 09:13 AM - Re: Stacked 14v systems for 28v (Eric M. Jones) 8. 09:21 AM - Re: Reasonable qualification for flight hardware? (Hinde, Frank George (Corvallis)) 9. 10:20 AM - Re: Re: Stacked 14v systems for 28v (Deems Davis) 10. 10:55 AM - Re: Re: Slick mag P-lead ground wire (aaa@pacifier.com) 11. 11:21 AM - Re: 'Scope offer from Saelig (Joe Garner) 12. 11:24 AM - Re: Re: Stacked 14v systems for 28v (Richard Tasker) 13. 01:35 PM - Re: Stacked 14v systems for 28v (Eric M. Jones) 14. 03:42 PM - Transistorture (Fiveonepw@aol.com) ________________________________ Message 1 _____________________________________ Time: 05:42:17 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Transorbs and Lightning At 09:45 AM 11/8/2006 -0600, you wrote: > > >So that would be a maybe? Sure . . . but 'maybe' comes in all sizes, flavors and assurances. When Paul's airplane took the hit it appears that the stroke came in one wingtip and out the other. Since the current carrying paths for this event was wiring, the qualification protocols would fall under "direct effects". See: http://www.aeroelectric.com/articles/Anatomy_of_a_Lightning_Strike.pdf I gotta tell ya, when you take the direct hit, the design goals have more to do with keeping the damage confined to the one system . . . there's no Transorb made that will confidently stand between mother nature's fireworks and your micro-processors, itty-bitty resistors and light bulbs. So yeah, I can agree that if Paul's airplane was generously fitted with Transorbs, he MIGHT have suffered a bit less damage. But as you can see from his post-event investigation, damage levels were high enough to leave tracks on structure, burned wires and caused internal damage sufficient to be manifest outside the devices enclosure. I cannot recommend the sprinkling of "Transorb dust" on your airplane because the notion is not supported by the understanding of simple-ideas. DO-160 testing and similar efforts are repeatable experiments that have been demonstrated over time to have value. There are numbers assigned to stress levels and techniques designed to stand off those hazards. If a builder is inclined to embrace "Transorb dust" as a good thing to do, I'll suggest there is risk that the same builder is subject to unsupported confidence in his/her system to knock on the gates of hell and run away unscathed. Many a good soul has been disappointed that boots and perhaps a hot-prop didn't take them through "that little bit of ice". To hypothesize about and recommend techniques that can only be tested at the edges of the airplane's envelope with pilot an passengers aboard is not good engineering. It's far better that we do not venture up to those edges. Bob . . . > > > > > >Bob et al. > > > >Some time ago my aircraft took a lightning hit which damaged many > >electronic devices, with the exception of the Apollo GX60 and SL70. > >Now I don't know if this was because these are well designed products > >or they were just having a lucky day, but my question, would a heavy > >duty transorb help in a catastrophic even like this ? > > > >Paul ________________________________ Message 2 _____________________________________ Time: 05:49:42 AM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Re: Stacked 14v systems for 28v At 05:52 PM 11/8/2006 -0700, you wrote: > >Well based on the response form Bob and others I revisited the Engine/Belt >driven A/C system. It turns out that with my engine and cowl combination >that there is not room enough to mount both a compressor and an >alternator. So, it looks like my options are; either to convert my >electric system to 28v (ugh!). or pursue the 'stacked' approach. > >Bob: > >When you say 'electrically isolated' are you saying that the "top" system >would have to NOT share a common ground with the bottom system? what other >'isolation' would be required > >"This would require a special alternator for the #2 machine." I assume >you are referring to the "top" system (?) could the SD-20 perform this >function as the alternator for the #2 machine, what is the "Special" >requirement of this alternator. No, the SD-20 is a 20amp machine. I'm suspecting that both of your 14 volt systems will need to be in the 60 amp class or larger. How much power does that a/c compressor need? The "top" system cannot be grounded to airframe. Alernators have diode arrays that are common to the alternator case by design. If I were crafting a floating system for stacking, I'd bypass the built in diodes and bring all of the alternator's field and stator wires out to be handled as needed for the system to run 14v above ground. >A bottom alternator large enough to carry ship's load plus the A/C load is >not a problem. > > >Re: backing up the bottom with the top. When you say 'complex switching' I >infer this is more than just the cross feed contactor approach in Z14, >care to elaborate any further? The problem is similar to the use of two batteries in series for starting and running them in parallel for flying. You need to sequence contactors in the right order to accomplish the switching . . . stuck contactors can create potential for spectacular events (a number of MU-2's were set on fire about 35 years ago before they installed limiters). >Thanks for the information and advice so far and for any additional >insight you can provide. This is a MAJOR task. You'll have to fabricate a special alternator regulator installation but is all possible. Bob . . . ________________________________ Message 3 _____________________________________ Time: 06:12:19 AM PST US From: "Mike Lehman" Subject: AeroElectric-List: Re: Slick mag P-lead ground wire Bob, I have found a certified aircraft with the P-lead shield grounded at the mag switch end as well as on the mag housing. Is there a down-side (i.e. noise) to grounding the shield at both ends? (Surprisingly, the Maintenance Manual for the aircraft does not include wiring for the mag switch or P-lead.) Mike >2) Do I ground the center conductor to a local ground point at the switch >on the panel or do I ground it to the coax outer conductor? Grounding to shield is preferred. See exemplar schematics in: http://aeroelectric.com/articles/Rev11/AppZ_R11J.pdf Bob . . . ________________________________ Message 4 _____________________________________ Time: 06:42:59 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Slick mag P-lead ground wire At 09:12 AM 11/9/2006 -0500, you wrote: > >Bob, > >I have found a certified aircraft with the P-lead shield grounded at the mag >switch end as well as on the mag housing. Is there a down-side (i.e. noise) >to grounding the shield at both ends? (Surprisingly, the Maintenance Manual >for the aircraft does not include wiring for the mag switch or P-lead.) There's a number of discussions for p-lead treatment in http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf and http://www.aeroelectric.com/FAQ/AeroElectric-List/AeroElectric-List_FAQ.pdf Open the .pdf files and search on "p-lead". In a nutshell, for best noise reduction -AND- avoidance of a fabricated ground loop, it's best to ground the shield at one end only (mag end) and use the shield as the ground return for the mag switch as illustrated in the z-figures and cited in the two links above. Bob . . . --------------------------------------------------------- < What is so wonderful about scientific truth...is that > < the authority which determines whether there can be > < debate or not does not reside in some fraternity of > < scientists; nor is it divine. The authority rests > < with experiment. > < --Lawrence M. Krauss > --------------------------------------------------------- ________________________________ Message 5 _____________________________________ Time: 06:47:21 AM PST US From: Deems Davis Subject: Re: AeroElectric-List: Re: Stacked 14v systems for 28v Thanks again Bob, The electric A/C system consumes 45 amps at peak load. Do _both_ alternators need to be capable of carrying ship's load plus the full load of the A/C?. If so, then that's going to put the Kabosh to this approach because there is not room enough to mount a 2nd 60-100A alt. (beginning to sound like an onerous task for an electric greenhorn) I was told that there is some 'new technology' (?) that will take the output from an externally regulated alternator and split it into 2 separate outputs, one being 12-14v and the other 24-28v. I'm trying to track this down, just wondering if you had heard anything on this tangent. Deems Davis # 406 Finishing - ( A Misnomer ! ) http://deemsrv10.com/ Robert L. Nuckolls, III wrote: > > No, the SD-20 is a 20amp machine. I'm suspecting that both > of your 14 volt systems will need to be in the 60 amp class > or larger. How much power does that a/c compressor need? > > >> Thanks for the information and advice so far and for any additional >> insight you can provide. > > > This is a MAJOR task. You'll have to fabricate a special > alternator regulator installation but is all possible. > > Bob . . . > > ________________________________ Message 6 _____________________________________ Time: 08:45:14 AM PST US From: Subject: AeroElectric-List: Reasonable qualification for flight hardware? 11/09/2006 Responding to a previous posting by Dave N6030X Subject: Re: AeroElectric-List: Reasonable qualification for flight hardware? You probably need to find out whether the FARs on light intensity apply to experimental aircraft or not. Google around a bit, because some pretty smart people have already done a lot of testing of LEDs for use in aircraft external lighting. It is common in the electronics manufacturing world to do "burn-in" testing for at least 2 or 3 days, during which time the device is cycled on for a few hours, off for a few hours, preferably including and possibly exceeding the temperature ranges in which the device is likely to be operating. Most electronic component failures are infant-mortality type, meaning that if they survive a few days of intensive testing, they will probably last a long time. Dave Morris ________________________________ Message 7 _____________________________________ Time: 09:13:25 AM PST US Subject: AeroElectric-List: Re: Stacked 14v systems for 28v From: "Eric M. Jones" Whenever this 28V from 14V subject comes up I implore the adventurous builder to get the right unit in the first place instead of trying to stuff this beast into the hole. Viz.--Buy the right-voltage unit. If there isn't one, call the manufacturer. Viz.--Modify the unit to run on 12V. Even this is easier than up-converting the 14 volts. Viz.--Do the whole job another way. Put dry ice in the glovebox, move to Alaska, open a window...whatever. It's surprising how cool sitting on a seat filled with silver dollars can be. Remember, voltage conversion is easy if the power is small. But FORGET IT when the power gets large. Find some other way. My two cents. "When trouble arises and things look bad, there is always one individual who perceives a solution and is willing to take command. Very often, that individual is crazy." --Dave Barry -------- 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=73387#73387 ________________________________ Message 8 _____________________________________ Time: 09:21:24 AM PST US Subject: RE: AeroElectric-List: Reasonable qualification for flight hardware? From: "Hinde, Frank George (Corvallis)" Sent: Thursday, November 09, 2006 9:15 AM Subject: RE: AeroElectric-List: Reasonable qualification for flight hardware? When I was researching this I noted that the Creative Air system is designed to meet the required FAA light intensity for certified AC...Thats why you have to angle the LED's in a specified manner as they are highly directional. Mind you the best test was when my hangar neighbour was drooling over my RV and looking at the lights and noting how cool the technology was...I switched on the position lights for him to see not realising he was staring straight at the lights....Temporarilly blinded the poor guy...One could assume the FAA ramp inspector would suffer the same fate if he doubted their effectiveness...:) Frank So I think that the answer to your question: "Do the FARs on light intensity apply to ABEA or not?" depends upon the actions of the individual initial airworthiness inspector. It may also be possible that an FAA inspector during a ramp inspection could raise this issue. ________________________________ Message 9 _____________________________________ Time: 10:20:22 AM PST US From: Deems Davis Subject: Re: AeroElectric-List: Re: Stacked 14v systems for 28v Thanks Eric, I appreciate the input, and I'm beginning to understand that this is a bigger task, than my limited skills/knowledge will support. So what about this for an 'approach' Use 28V alternator (100amp capacity) 28V starter 2 14V batteries connected in series to produce 28V to the A/C Take a 12-14/v feed off of the 1st battery and use that to drive the existing 12V electro whizzies. ? Or should I just sweat and save some $'s Deems Davis # 406 Finishing - ( A Misnomer ! ) http://deemsrv10.com/ Eric M. Jones wrote: > >Whenever this 28V from 14V subject comes up I implore the adventurous builder to get the right unit in the first place instead of trying to stuff this beast into the hole. > >Viz.--Buy the right-voltage unit. If there isn't one, call the manufacturer. > >Viz.--Modify the unit to run on 12V. Even this is easier than up-converting the 14 volts. > >Viz.--Do the whole job another way. Put dry ice in the glovebox, move to Alaska, open a window...whatever. It's surprising how cool sitting on a seat filled with silver dollars can be. > >Remember, voltage conversion is easy if the power is small. But FORGET IT when the power gets large. Find some other way. > >My two cents. > >"When trouble arises and things look bad, >there is always one individual who perceives >a solution and is willing to take command. >Very often, that individual is crazy." > --Dave Barry > >-------- >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=73387#73387 > > > > ________________________________ Message 10 ____________________________________ Time: 10:55:47 AM PST US Subject: Re: AeroElectric-List: Re: Slick mag P-lead ground wire From: aaa@pacifier.com Thanks Bob. I will ground to the shield this weekend!!! Duane > > > At 09:12 AM 11/9/2006 -0500, you wrote: > >> >> >>Bob, >> >>I have found a certified aircraft with the P-lead shield grounded at the >> mag >>switch end as well as on the mag housing. Is there a down-side (i.e. >> noise) >>to grounding the shield at both ends? (Surprisingly, the Maintenance >> Manual >>for the aircraft does not include wiring for the mag switch or P-lead.) > > There's a number of discussions for p-lead treatment in > > http://www.aeroelectric.com/articles/MagnetoSwitchOptions.pdf > > and > > http://www.aeroelectric.com/FAQ/AeroElectric-List/AeroElectric-List_FAQ.pdf > > Open the .pdf files and search on "p-lead". > > In a nutshell, for best noise reduction -AND- avoidance of > a fabricated ground loop, it's best to ground the shield at > one end only (mag end) and use the shield as the ground return > for the mag switch as illustrated in the z-figures and cited > in the two links above. > > Bob . . . > > --------------------------------------------------------- > < What is so wonderful about scientific truth...is that > > < the authority which determines whether there can be > > < debate or not does not reside in some fraternity of > > < scientists; nor is it divine. The authority rests > > < with experiment. > > < --Lawrence M. Krauss > > --------------------------------------------------------- > > ________________________________ Message 11 ____________________________________ Time: 11:21:52 AM PST US From: Joe Garner Subject: Re: AeroElectric-List: 'Scope offer from Saelig Hi Bob, Just wondering what you think of the 'scope after a few months? Thanks, Joe Robert L. Nuckolls, III wrote: > > > A few days ago I mentioned an oscilloscope being offered by > Saelig at: > > http://saelig.com/ > > I just received the one I had on order. It's a rough clone > of the Tektronix TDS200 series scopes. Only 25 Mhz but it's > in color. Comes with two probes ($50 value alone). The USB > cable and attending software lets you dump both image and > tabular data to a computer. Here's the test setup on my > bench. > > http://www.aeroelectric.com/Pictures/Tools/PDS5022S_OWON_Scope.jpg > > Once the data has been dumped to the computer it can be manipulated > in a variety of ways including print to hard copy. Haven't had > occasion to do any serious measurements but I can say that for > $299, it's a hell-of-a-buy. > > I'm going to use it as my 'beater' scope to drag around > for looking into problems on airplanes and save my Tek > for less stressful bench work. > > > > Bob . . . > > ________________________________ Message 12 ____________________________________ Time: 11:24:51 AM PST US From: Richard Tasker Subject: Re: AeroElectric-List: Re: Stacked 14v systems for 28v Unfortunately, unless the other electrowhizzies are very low amperage, you will be forever overcharging the second battery with this arrangement. Depending what the amp draw of your other 12V electrowhizzies are you might try using a 28V to 14V converter for them. Also, be aware that a lot of the newer electrowhizzies will run from 12-28V so you could run those off the 28V. Depending on your mix of electronics you might be able to run the majority off the 28V and run a few low draw units from the second battery or from a small 28 to 14V converter. There are certainly ways to do what you want to do, but I suspect that you may end up sweating... Dick Tasker Deems Davis wrote: > > Thanks Eric, I appreciate the input, and I'm beginning to understand > that this is a bigger task, than my limited skills/knowledge will > support. > So what about this for an 'approach' > > Use 28V alternator (100amp capacity) > 28V starter > 2 14V batteries connected in series to produce 28V to the A/C > Take a 12-14/v feed off of the 1st battery and use that to drive the > existing 12V electro whizzies. > > ? > > > Or should I just sweat and save some $'s > > Deems Davis # 406 > Finishing - ( A Misnomer ! ) > http://deemsrv10.com/ > > > Eric M. Jones wrote: > >> >> >> Whenever this 28V from 14V subject comes up I implore the adventurous >> builder to get the right unit in the first place instead of trying to >> stuff this beast into the hole. >> >> Viz.--Buy the right-voltage unit. If there isn't one, call the >> manufacturer. >> >> Viz.--Modify the unit to run on 12V. Even this is easier than >> up-converting the 14 volts. >> >> Viz.--Do the whole job another way. Put dry ice in the glovebox, move >> to Alaska, open a window...whatever. It's surprising how cool >> sitting on a seat filled with silver dollars can be. >> Remember, voltage conversion is easy if the power is small. But >> FORGET IT when the power gets large. Find some other way. >> >> My two cents. >> >> "When trouble arises and things look bad, >> there is always one individual who perceives >> a solution and is willing to take command. >> Very often, that individual is crazy." >> --Dave Barry >> >> -------- >> 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=73387#73387 >> >> >> >> >> >> >> >> >> >> >> >> >> >> > > ________________________________ Message 13 ____________________________________ Time: 01:35:22 PM PST US Subject: AeroElectric-List: Re: Stacked 14v systems for 28v From: "Eric M. Jones" If you Google "12 volt air conditioner" you get a boatload of hits. I'd search very hard for a 12V solution on the internet. Consider that almost all 12V cars have air conditioners--with the compressor running off the engine. Do you need a huge electric motor to keep cool when the engine is not running? Is this a mode of operation important to you? Better an engine-driven compressor than a second alternator. They used to use ground a/c. Could your operation do this? I come at this question from a desire to minimize weight and complexity. My air conditioning comes from the big fan in the nose. This may not be where you are coming from. "Nothing is too wonderful to be true." James Clerk Maxwell, discoverer of electromagnetism "Too much of a good thing can be wonderful." Mae West, discoverer of personal magnetism -------- 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=73420#73420 ________________________________ Message 14 ____________________________________ Time: 03:42:12 PM PST US From: Fiveonepw@aol.com Subject: AeroElectric-List: Transistorture Howdy those-that-know- I am (as usual) trying something I know little about, but he'p me out here, purty please! Goal: light an annunciator LED when Trutrak servos are OFF. This is a reminder that Digiflight is not flying the airplane. Normal condition is A/P on for normal flight with LED OFF. Suggestion from Trutrak: connect NPN Darlington transistor base via a 10K resistor to servo torque line on servo connector (pin 6- common to pin 4 or 16 on back of Digitrak depending on pitch or roll servo) . Connect 12v to annunciator LED+, LED ground to emitter and use transistor collector to ground lamp. If I got this right, the signal from the servo turns transistor on, completing LED circuit, LED comes ON. Problem is, Trutrak offered no guidance beyond "Darlington NPN transistor" and I have googled, Digikeyed & Mousered trying to find an appropriate transistor. The values are mystifying and require much research & education to demystify. Best quess is this one in a TO-92 package: http://rocky.digikey.com/scripts/ProductInfo.dll?Site=US&V=488&M=2N6426G Supposing this is a good choice to turn the LED ON, can I turn the LED OFF by using this transistor circuit to turn on a small relay and use relay N.C. contacts connected to LED ground to turn off the LED when servo is energized, and if so, what would be an appropriate relay? Or is there a better way to do this? I humble myself before y'all but THANKS just the same for any advice! Mark Phillips