---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 10/15/13: 25 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 01:32 AM - Re: Relay for Critical Power Feed (Eric Page) 2. 04:48 AM - Re: New electrical architecture with ENGINE BUS (user9253) 3. 07:39 AM - Re: Re: New electrical architecture with ENGINE BUS (Fred Klein) 4. 08:06 AM - Copper Foil width for VOR antenna (p32gxy) 5. 08:09 AM - Re: diodes (Fred Klein) 6. 08:38 AM - Re: New electrical architecture with ENGINE BUS (user9253) 7. 09:13 AM - Re: Re: New electrical architecture with ENGINE BUS (Ken) 8. 09:29 AM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 9. 09:43 AM - Re: Re: diodes (Charlie England) 10. 09:48 AM - Re: Re: diodes (Eric Page) 11. 10:03 AM - Re: Re: New electrical architecture with ENGIN E BUS (jan) 12. 10:33 AM - Re: Re: New electrical architecture with ENGINE BUS (Bob McCallum) 13. 10:37 AM - Re: Copper Foil width for VOR antenna (The Kuffels) 14. 11:40 AM - Re: iPad charger? (ronaldcox) 15. 11:59 AM - Re: Re: diodes (infow) 16. 12:40 PM - Re: Copper Foil width for VOR antenna (p32gxy) 17. 01:34 PM - Re: Re: Copper Foil width for VOR antenna (The Kuffels) 18. 02:29 PM - Re: Copper Foil width for VOR antenna (p32gxy) 19. 02:54 PM - Re: EXP 2 Bus workaround (Fred Klein) 20. 07:51 PM - Re: Re: New electrical architecture with ENGINE BUS (Robert L. Nuckolls, III) 21. 07:56 PM - Re: EXP 2 Bus workaround (Bill Bradburry) 22. 08:04 PM - Re: Re: diodes (Robert L. Nuckolls, III) 23. 08:04 PM - Re: EXP 2 Bus workaround (Robert L. Nuckolls, III) 24. 08:22 PM - Re: New electrical architecture with ENGINE BUS (Robert L. Nuckolls, III) 25. 08:22 PM - Re: Re: Copper Foil width for VOR antenna (Robert L. Nuckolls, III) ________________________________ Message 1 _____________________________________ Time: 01:32:06 AM PST US Subject: Re: AeroElectric-List: Relay for Critical Power Feed From: Eric Page Following up on automotive relays. I tested six 12V coil, 40A, SPDT automotive relays (Hsin Da 961A-1C-12DM) to determine "make" and "break" coil voltages. I connected each one to a vari able power supply, and clipped multimeter leads directly at the relay's coil contacts. Make voltage was determined by slowly increasing voltage until t he relay closed, break voltage by slowly decreasing until it opened. Coil resistance ranged from 91.5 to 92.7 ohms. Relay 1: Make 6.81V Break 3.85V Relay 2: Make 5.80V Break 3.85V Relay 3: Make 5.87V Break 2.03V Relay 4: Make 6.69V Break 3.51V Relay 5: Make 6.42V Break 3.15V Relay 6: Make 6.46V Break 3.79V Average: Make 6.34V Break 3.36V Relays sat stationary on the bench during tests. Vibration in real-world us e would almost certainly alter these results just bit. Next I did a very unscientific check of holding force. I crimped PIDG fast- on connectors to two wires and connected them to the normally open relay con tacts. I fed 5V from a power supply, through a 100k resistor, through these wires, with an oscilloscope probe attached across the resistor. I set the r elay coil voltage from another power supply at 14.0V, so that the relay clos ed and the scope displayed a constant 5V DC. I set the scope to trigger on a falling slope at 4.7V. I then slapped the relay against the bench top in e very direction except pins-down, until the contacts bounced. A typical boun ce waveform is attached. I have no idea how many g it took to bounce the co ntacts, but it was a pretty solid smack. Certainly much more severe than an y turbulence I care to encounter! Eric On Oct 11, 2013, at 4:29 PM, Eric Page wrote: > That's a novel idea, Tom. It would work, if you assume that failure of PS #1 always means instantaneous loss of power output. This would immediately d e-energize the relay coil and allow feed from PS#2. > > If, however, PS#1 suffered a slow ramp-down of output voltage (as with a f ailed alternator leaving a battery to supply the bus), then bus voltage woul d likely sag below the minimum for operation of the critical component befor e the relay de-energized. > > Relay coils exhibit substantial hysteresis; they require a higher voltage t o energize than to de-energize. A 12V-rated relay might energize at 9V risi ng, but not de-energize until 6V falling. A 12V battery would be effectivel y dead long before the relay opened. > > This is why the diode bridge works so well. Whichever main bus has the hi gher voltage supplies the critical bus, and switchover is seamless, with no d ropout during the change. > > I have a bag of automotive relays on the shelf. I'll try to remember to c haracterize their behavior when I get home on Monday and report back. > > Eric > > > On Oct 11, 2013, at 11:18 AM, Thomas E Blejwas wrot e: >> Bob, >> >> In Z-19, you use a diode bridge for critical power feeds. Can a relay be used instead? For example: connect Power Source #1 to terminal 86 and to t he critical component; connect Power Source #2 to terminal 30; and 87a to th e critical component. If both switched on, power comes from #1, otherwise p ower comes from whichever is switched on. Seems that this has the advantage of no need for a heat sink and failure of the relay does not prevent power t o the critical component. What am I missing? Thanks. >> >> Tom
________________________________ Message 2 _____________________________________ Time: 04:48:32 AM PST US Subject: AeroElectric-List: Re: New electrical architecture with ENGINE BUS From: "user9253" > can you remind me what software you use to produce such drawings? I use TurboCAD Professional 16.2 Full Edition. Aircraft electrical system drawings and symbols are available for free download from Bob Nuckolls website: http://www.aeroelectric.com/PPS/ Thanks Bob. Older versions of TurboCAD are for sale on Amazon for $10 to $30 (sort by price). I am not familiar with the different versions of TurboCAD, but would get a deluxe version. Files can be saved in many different formats. For sharing drawings with others, I save them as pdf because they can be zoomed in without blurring. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410596#410596 ________________________________ Message 3 _____________________________________ Time: 07:39:58 AM PST US From: Fred Klein Subject: Re: AeroElectric-List: Re: New electrical architecture with ENGINE BUS On Oct 14, 2013, at 5:29 PM, user9253 wrote: >> Am I right in surmising that my EXP Bus could serve as the Main Power Distribution Bus? > > Yes, but the EXP Bus should not shut off battery contactors that supply power to the engine bus. And it is safer to have the master relay located close to the power source rather than inside of the EXP Bus. Try to keep smoke on the other side of the firewall away from you. Joe...I need to look into this a bit further...the EXP Bus instructions recommend that when battery is more than 3 feet away from Bus that an external solenoid be used in place of the internal master relay...the narrative adjacent to Fig. 8 in the EXP Bus installation instructions makes this clear...and the mfg'r provides a jumper to replace the relay...(I've done that)...HOWEVER, it's also clear that the mfg'r's diagram for the External Solenoid installation did NOT remove the "box" entitled "Master Relay". At least, that's what I surmise at the moment and I'll be trying to confirm that today. So...if I continue to use the EXP Bus, rest assured that the EXP master switch activates the (external) contactor #1 as shown on my now quite obsolete circuit diagram. >> How would you feel about your diagram if the 2 battery contactors were mounted on the engine side of the firewall? > > It is much safer to disconnect the power as close to the source as possible in the event of an electrical fire or imminent forced landing. ...OK...I get it...and...in my fiberglass airframe, can I bring a SINGLE 4AWG ground directly to the engine? And, can I (should I?) use a brass strap to connect the (-) sides of the contactors? Fred ________________________________ Message 4 _____________________________________ Time: 08:06:36 AM PST US Subject: AeroElectric-List: Copper Foil width for VOR antenna From: "p32gxy" Hello all, I am installing a Jim Weir style copper tape antenna in the wing of my composite aircraft. I have the choice of 3/8 or 1/2 inch wide copper tape... will going with one or the other make any real difference for a VOR antenna? Thx, M Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410610#410610 ________________________________ Message 5 _____________________________________ Time: 08:09:25 AM PST US Subject: AeroElectric-List: Re: diodes From: Fred Klein On Oct 14, 2013, at 6:54 AM, Joe wrote: > Yes, diodes are required across contactor coils to prevent voltage spikes. Voltage spikes, if not suppressed, can damage the switches that supply power to the contactor coils. With or without the diodes, there is no danger to avionics. Thanks for the clarification Joe. I've done some research on the contactors I bought at Acft Spru; P/N 11-03161, a contactor manufactured by White - Rogers w/ their product number of 70 111226 6. I've asked whether or not the relay IS or IS NOT "protected by a diode to reduce the voltage spike seen when the contactor is turned on. After contacting the mfg'r and its parent company and getting some initial runaround about internal circuitry being proprietary, I have been told that this contactor does NOT have such a diode....caveat emptor. I'll be replacing mine w/ the B & C contactors. Fred ________________________________ Message 6 _____________________________________ Time: 08:38:15 AM PST US Subject: AeroElectric-List: Re: New electrical architecture with ENGINE BUS From: "user9253" > ...in my fiberglass airframe, can I bring a SINGLE 4AWG ground directly to the engine? The size of the wire depends on the starter current and also the distance between the battery and the starter. The negative wire is just as important as the positive wire. If you use a singe wire, be 100 percent sure that the connections at each end will not loosen or corrode. The same can be said for the positive wire (if only one is used). > can I (should I?) use a brass strap to connect the (-) sides of the contactors? Contactors do not have a negative side unless you are talking about the coil. If you use 2 battery contactors, then the negative side of each coil is connected to a separate switch. A brass strap could be used to connect the negative terminals of 2 batteries together. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410614#410614 ________________________________ Message 7 _____________________________________ Time: 09:13:27 AM PST US From: Ken Subject: Re: AeroElectric-List: Re: New electrical architecture with ENGINE BUS It is good to have two ground straps on an electric dependant engine. There are a few cases of failed single ground straps causing sudden quiet. I noticed one of mine was not as tight as it should have been on an annual inspection. Ken On 15/10/2013 11:33 AM, user9253 wrote: > > > >> ...in my fiberglass airframe, can I bring a SINGLE 4AWG ground >> directly to the engine? > > The size of the wire depends on the starter current and also the > distance between the battery and the starter. The negative wire is > just as important as the positive wire. If you use a singe wire, be > 100 percent sure that the connections at each end will not loosen or > corrode. The same can be said for the positive wire (if only one is > used). > >> can I (should I?) use a brass strap to connect the (-) sides of the >> contactors? > > Contactors do not have a negative side unless you are talking about > the coil. If you use 2 battery contactors, then the negative side of > each coil is connected to a separate switch. A brass strap could be > used to connect the negative terminals of 2 batteries together. Joe > > -------- Joe Gores > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=410614#410614 > > ________________________________ Message 8 _____________________________________ Time: 09:29:12 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround > How many pumps? My engine is designed to run on one pump; I have a back up pump as well; each pump has it's own filter; the back up is intended to handle failure or clogging of the first pump. The hi pressure pumps draw 5.7 amps each. Both pumps should be able to be energized by either battery...and...it seems to me that I should want to toggle switch from one pump to the other. Why all this layered 'redundancy'. Under what conceivable condition can you imagine that you'll be siting in the cockpit with a stumbling engine flipping switches to see what combination of positions gets the engine back? There are folks who make good money sifting BIG spreadsheets of numbers that speak to failure rates of individual parts for which (1) there are ESTABLISHED failure rate numbers . . . i.e., "This resistor, when used within these limits, has a CALCULATED failure rate of 3.8 x 10 to the minus 10. Meaning that if you really operated a large sample of such resistors until 99% of them are failed, you would get a bell shape curve of failures starting with some very tiny number failing in say 100 hours, and an equally tiny number failing in about 2X the calculated rate with a peak in the numbers at the calculated number. Now, take a constellation of such parts and build an electro-whizzy. Add all the effects of failures for the assembly and you get an Mean Time Between Failures number for the product. People who sit behind desks and write rules like to hang their hats on MTBF. . . and think they're doing a good and useful thing. In my experience, all this failure rate stuff is 99% smoke and mirrors. ALL machines flying electro-whizzies with MTBF numbers have things break every day. That's what keeps the mechanics employed. If a particular electro-whizzy shows a proclivity for failure at some number of hours much lower than predicted MTBF, do the folks behind the desks issue an AD and ground the fleet? No, those events go relatively un-charted assuming that (1) FMEA demonstrates that the failures do not put the airframe at risk and/or (2) the cost of added maintenance is insufficient to get the fleet operator's bean counters in a tizzy. So how does all this feathers and flooby-dust in the BIG airplanes guide our thinking for little airplanes? Easy. Easy, we do FMEA and then see how much cash is in your wallet. Let us assume that the gizmos you put in your airplane have a demonstrated MTBF of 500 hours. Terrible. That thing would never be allowed in the door at Boeing. But what's the significance of such dismal failure numbers? 500 hours of operation in the average light airplane is 10 years of service life. The 500 hour number suggests that about half of all such devices will have failed in 10 years. If that device is needed for continued flight, then what is the prudent prophylactic against bad-day-in-the- cockpit syndrome? Easy, install two of them. Hmmm . . . now what are the chances that BOTH devices would fail at the same time? Each device SHOULD be pre-flight tested. The maximum duration of the flight is on the order of 4 hours. So what is the likelihood of dual failure in that 4-hour window? What is the likelihood that failure of one pump will be teamed up with failure of a battery or the wiring and controls associated with that pump in that same 4-hour window? The pump is probably a vane style device driven by a brushed motor. The vulnerable components of this device are brushes, vanes and bearings. If all flights are normally conduced with the same pump, then wear-rate that attacks serviceability of the second pump is zero. This begs the question, "What value is added by multiple feed paths from multiple power sources to each pump?" That pump probably has a real MTBF on the order of 500 hours . . . yet there are many of them in service on airplanes. Dual fuel injectors? Seems unlikely. My engine is MPEFI; it has 4 fuel injectors...each one draws between 1 and 2 amps. Can you get us a resistance measurement of an injector coil? A fuel injector is opened for milliseconds once every other revolution of the crankshaft. So there are TWO values of significance to our deliberations. (1) PEAK current set by the coil resistance which drives wire sizing and noise issues and (2) AVERAGE current under most demanding engine operations. The second number is seldom articulated by engine suppliers in the OBAM aircraft industry. But this is the critical number for deducing ENERGY necessary to keep the engine running. Though I drove one years ago, (a '65 convertible), I have no idea how the conversion guys are setting it up. My engine has 4 coils...all together they draw 8 amps. My engine has dual electronic ignition thanks to (I believe) dual Hall effect sensors...I don't know what, if any, their current draw is. The same line of reasoning applies to ignition coils too. 2A per coil paints a picture of 24 watts being dissipated in each coil . . . a coil that is called upon to deliver millijoules (milliwatt-seconds) of energy to a plug every other revolution. Not a very efficient system. Klaus Savier's electronic ignition for a 6 cylinder engine draws 25 watts for ALL SIX plugs at max RPM. There's a disconnect here Will do...here's how I see it...to keep the prop spinning, I need: 1. The ECU (normal)...it has 3 power feeds...one for the "box" drawing 0.5 amps...one for the fuel injectors drawing 4 to 8 amps...and one for the coils drawing 8 amps (continuous...but engine guy sez during start up, draw could spike momentarily to 20 amps). Total continuous load: 16.5 amps. I am suspicious of those numbers for reasons cited. This engine guy would do well by his customers and himself to get some real instrumented numbers off of his product's electro-whizzies. If I were putting his engine on a TC aircraft, those numbers would be necessary. This isn't a whimsical demand unique to the certified aircraft market, it's fundamental to knowing how it works in any airplane. ECU (back up): It contains a duplicate motherboard accessed via a toggle switch on the control panel...no change in electrical load. 2. One serviceable fuel pump w/ an unclogged filter. Fuel pump draws 5.7 amps. Fuel pump (back up): I have a second pump (same rating as first) w/ separate filter. I BELIEVE that's all I need to keep the engine running...total load: 22.2 amps. (Round it up to say 25 amps?...what have I missed?) REAL numbers that I believe will prove to be much smaller. 250 Watts demand by an engine that's fitted with only 550 Watts of alternator seems out of whack. Are these engines flying now? What's the change that the supplier of this engine could be persuaded to get some real numbers off of a customer's airplane . . . or perhaps his own? If this electrical load for the engine is routed thru a (always hot?) battery bus, would we then want to tally up additional loads on an endurance bus as a back up to everything deemed essential which would be normally drawing from the EXP Bus in the event that the EXP fizzles? You're talking dual failure in the span of time needed to use all fuel aboard. The only reason you need to run the engine battery-only is if the alternator quits. If this were a Part 23 aircraft, we don't consider dual failures as part of the cert process. If the guys behind the desks don't worry about it . . . well . . . they're paid to worry. We get to do our own FMEA based mitigation of risk. And how do we provide the juice if the alternator fizzles as well? Note: regarding batteries: the Odyssey PC680 capacity is 16 ah, providing 24 "reserve minutes @ 25 amps"...see: http://www.odysseybatteries.com/mainpages/batteries.htm Assuming dual batteries and both battery states of 75%, I figure 24 ah available which would give 36 "reserve minutes" @ 25 amp draw. Does that sound right to you?...or am I getting way ahead of myself? Just a little . . . and if the numbers you've been offered are real, then alternator failure on your airplane would be an emergency situation. 30 minutes of battery-only endurance comes with severe pucker-factor. Are you really sure you want to fly this engine under that kind of risk? A rhetorical question at this stage of the design . . . I can't imagine an automotive manufacturer willing to toss off that kind of energy budget just to keep the engine running. I'll bet that engine in a car would run for hours on a good battery if all other loads were eliminated. Let's talk with your engine guy. Bob . . . ________________________________ Message 9 _____________________________________ Time: 09:43:40 AM PST US From: Charlie England Subject: Re: AeroElectric-List: Re: diodes On 10/15/2013 9:55 AM, Fred Klein wrote: > > On Oct 14, 2013, at 6:54 AM, Joe wrote: > >> Yes, diodes are required across contactor coils to prevent voltage >> spikes. Voltage spikes, if not suppressed, can damage the switches >> that supply power to the contactor coils. With or without the >> diodes, there is no danger to avionics. > > Thanks for the clarification Joe. > > I've done some research on the contactors I bought at Acft Spru; > P/N 11-03161, a contactor manufactured by White - Rogers w/ their > product number of 70 111226 6. > > I've asked whether or not the relay IS or IS NOT "protected by a diode > to reduce the voltage spike seen when the contactor is turned on. > > After contacting the mfg'r and its parent company and getting some > initial runaround about internal circuitry being proprietary, I have > been told that this contactor does NOT have such a diode....caveat emptor. > > I'll be replacing mine w/ the B & C contactors. > > Fred > I missed the original post, so I might not have all info needed for a reply, but here goes: not having a diode across a relay's coil (as purchased) is more the norm than the exception. Diodes for the job described are dirt cheap (pennies, last time I checked) & available anywhere you can buy electronic components. If the contactor does what you need it to do, just add the diode. Charlie ________________________________ Message 10 ____________________________________ Time: 09:48:01 AM PST US Subject: Re: AeroElectric-List: Re: diodes From: Eric Page Fred, It would be easier and cheaper to add the diode externally to your existing c ontactor. They're available at your local Radio Shack for $3.49 for 25. If you don't have a RS close by, Digi-Key has them for $0.11 ea. (less in quan tity) and their shipping via 1st Class Mail is very reasonable. Digi-Key: http://tinyurl.com/m9ywoxc Radio Shack: http://tinyurl.com/ksswgfp Eric On Oct 15, 2013, at 7:55 AM, Fred Klein wrote: > On Oct 14, 2013, at 6:54 AM, Joe wrote: > >> Yes, diodes are required across contactor coils to prevent voltage spikes . Voltage spikes, if not suppressed, can damage the switches that supply po wer to the contactor coils. With or without the diodes, there is no danger t o avionics. > > Thanks for the clarification Joe. > > I've done some research on the contactors I bought at Acft Spru; P/N 11-03 161, a contactor manufactured by White - Rogers w/ their product number of 7 0 111226 6. > > I've asked whether or not the relay IS or IS NOT "protected by a diode to r educe the voltage spike seen when the contactor is turned on. > > After contacting the mfg'r and its parent company and getting some initial runaround about internal circuitry being proprietary, I have been told that this contactor does NOT have such a diode....caveat emptor. > > I'll be replacing mine w/ the B & C contactors. > > Fred ________________________________ Message 11 ____________________________________ Time: 10:03:31 AM PST US From: jan Subject: RE: AeroElectric-List: Re: New electrical architecture with ENGIN E BUS For working with DXF files I would use the free program DraftSight http://www.3ds.com/products-services/draftsight/download-draftsight/ Jan -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of user9253 Sent: 15 October 2013 12:45 Subject: AeroElectric-List: Re: New electrical architecture with ENGINE BUS > can you remind me what software you use to produce such drawings? I use TurboCAD Professional 16.2 Full Edition. Aircraft electrical system drawings and symbols are available for free download from Bob Nuckolls website: http://www.aeroelectric.com/PPS/ Thanks Bob. Older versions of TurboCAD are for sale on Amazon for $10 to $30 (sort by price). I am not familiar with the different versions of TurboCAD, but would get a deluxe version. Files can be saved in many different formats. For sharing drawings with others, I save them as pdf because they can be zoomed in without blurring. Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410596#410596 ________________________________ Message 12 ____________________________________ Time: 10:33:26 AM PST US From: Bob McCallum Subject: RE: AeroElectric-List: Re: New electrical architecture with ENGINE BUS A brass strap should NOT be used to connect the two battery negative termin als together. The only thing connected to any battery terminal should be so ft flexible welding cable to reduce the risk of vibration failure of the te rminals themselves. A rigid brass strap will transmit vibration from one ba ttery to the other with the possibility of breaking off the terminal on one or the other. Bob McC > Subject: AeroElectric-List: Re: New electrical architecture with ENGINE B US > From: fransew@gmail.com > Date: Tue=2C 15 Oct 2013 08:33:45 -0700 > To: aeroelectric-list@matronics.com > > > > > ...in my fiberglass airframe=2C can I bring a SINGLE 4AWG ground direct ly to the engine? > > The size of the wire depends on the starter current and also the distance between the battery and the starter. The negative wire is just as importa nt as the positive wire. If you use a singe wire=2C be 100 percent sure th at the connections at each end will not loosen or corrode. The same can be said for the positive wire (if only one is used). > > > can I (should I?) use a brass strap to connect the (-) sides of the con tactors? > > Contactors do not have a negative side unless you are talking about the c oil. If you use 2 battery contactors=2C then the negative side of each coi l is connected to a separate switch. A brass strap could be used to connec t the negative terminals of 2 batteries together. > Joe > > -------- > Joe Gores > > > > > Read this topic online here: > > http://forums.matronics.com/viewtopic.php?p=410614#410614 > > > > > > > =========== =========== =========== =========== > > > ________________________________ Message 13 ____________________________________ Time: 10:37:42 AM PST US From: "The Kuffels" Subject: Re: AeroElectric-List: Copper Foil width for VOR antenna << I am installing a Jim Weir style copper tape antenna in the wing of my composite aircraft. I have the choice of 3/8 or 1/2 inch wide copper tape... will going with one or the other make any real difference for a VOR antenna? >> Real difference? No. The wider tape will give you in theory a wider bandwidth antenna but the performance difference is hard to detect. But if I had the wider tape available anyway, I would use it. Besides, the wider tape is marginally more mechanically robust. The foil tapes have a history of breaking when installed in flexing locations such as landing gear. Tom Kuffel ________________________________ Message 14 ____________________________________ Time: 11:40:13 AM PST US Subject: AeroElectric-List: Re: iPad charger? From: "ronaldcox" Folks, I hope I haven't led anyone astray on my earlier question about this device. http://www.amazon.com/Brand-Blue-Sea-Charger-Socket/dp/B00FBQX23A/ref=sr_1_6?s=electronics&ie=UTF8&qid=1381860353&sr=1-6&keywords=blue+sea+usb It works well, seems to provide enough juice to power my iPad mini, and all the other stuff I mentioned is true. But I've decided my characterization of the noise issue isn't so accurate after more testing. It does put out quite a bit of EMI "hash" that breaks the non-adjustable squelch on my VHF radio, so it's probably not going to find a permanent home in my panel. I still like the form factor, physical quality, etc., so if one of you Eric's comes up with a good back end for it, I may just use it for the output ports, and gut the electronic end if one of your devices will do a better (electrically quieter) job. Standing by for either the new one that Eric Page is designing, or a new run of the ones Eric Jones is talking about. Let me know if/when one of you gets something you want to put out there, either for testing (I'm game) or it's available for sale. Thanks, Ron -------- Ron Cox Glasair Super II F/T Under Construction at C77 - About to fly! Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410636#410636 ________________________________ Message 15 ____________________________________ Time: 11:59:21 AM PST US From: infow Subject: Re: AeroElectric-List: Re: diodes You can get both contactors and diodes from Van's Aircraft! Reasonable cost and cheap shipping... like most of their parts. Ron >: On Oct 14, 2013, at 6:54 AM, Joe wrote: >: >:>: Yes, diodes are required across contactor coils to prevent voltage spikes. Voltage >:>: spikes, if not suppressed, can damage the switches that supply power to the >:>: contactor coils. With or without the diodes, there is no danger to avionics. >:>: >: >: Thanks for the clarification Joe. >: >: >: I've done some research on the contactors I bought at Acft Spru; P/N 11-03161, a >: contactor manufactured by White - Rogers w/ their product number of 70 111226 6. >: >: >: I've asked whether or not the relay IS or IS NOT "protected by a diode to reduce the >: voltage spike seen when the contactor is turned on. >: >: >: After contacting the mfg'r and its parent company and getting some initial runaround >: about internal circuitry being proprietary, I have been told that this contactor does >: NOT have such a diode....caveat emptor. >: >: >: I'll be replacing mine w/ the B & C contactors. >: >: >: Fred >: http://www.matronics.com/Navigator?AeroElectric-List >: MATRONICS WEB FORUMS - >: http://www.matronics.com/contribution ________________________________ Message 16 ____________________________________ Time: 12:40:17 PM PST US Subject: AeroElectric-List: Re: Copper Foil width for VOR antenna From: "p32gxy" Ok... got the bandwidth angle... as planned now it would be installed in tension mostly... my other option is to use part of the coax itself as the legs of the V shaped dipole any thoughts? Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410640#410640 ________________________________ Message 17 ____________________________________ Time: 01:34:13 PM PST US From: "The Kuffels" Subject: Re: AeroElectric-List: Re: Copper Foil width for VOR antenna << part of the coax itself as the legs of the V shaped dipole >> This has been done often in composite fuselages. It certainly is more physically robust than the foil tapes. The difference in bandwidth between the thin center conductor and the foil tape versions is measurable with less than lab quality equipment but the difference in performance is still not perceptible. Be sure to seal the end of the cable where the shield and the center conductor split to form the legs of the antenna with something like Performix Liquid Tape (Walmart Auto Section). Also seal the end of the center conductor. If water gets into the coax you will detect lower performance. Tom Kuffel ________________________________ Message 18 ____________________________________ Time: 02:29:30 PM PST US Subject: AeroElectric-List: Re: Copper Foil width for VOR antenna From: "p32gxy" Thx... I am actually thinking of using the braid only as the antenna material... as part of making a proper balun one would only use the braid to connect to the antenna elements anyway while the center cnnductor is not connected... this should avoid the problem you are describing... as long as i can successfully slide about a 16" long undisturbed braid-external shielding up on the stripped coax to avoid the large resulting gap. Water will not get into this setup as it will be saturated with epoxy. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=410647#410647 ________________________________ Message 19 ____________________________________ Time: 02:54:22 PM PST US From: Fred Klein Subject: Re: AeroElectric-List: EXP 2 Bus workaround On Oct 15, 2013, at 9:22 AM, Robert L. Nuckolls, III wrote: > > How many pumps? > > My engine is designed to run on one pump; I have a back up pump as well; each pump has it's own filter; the back up is intended to handle failure or clogging of the first pump. The hi pressure pumps draw 5.7 amps each. Both pumps should be able to be energized by either battery...and...it seems to me that I should want to toggle switch from one pump to the other. > > Why all this layered 'redundancy'. Under what conceivable > condition can you imagine that you'll be siting in the > cockpit with a stumbling engine flipping switches to see > what combination of positions gets the engine back? Bob...to answer your question, a clogged fuel filter is eminently conceivable to me...to provide a back up pump with separate filter seems fundemental...to be able to switch from one pump to another seems straightforward enough. I'm simply mystified as to why you imply that "this layered 'redundancy' " would create rather than solve problems or confusion if the engine starts sputtering. What am I missing here? Fred ________________________________ Message 20 ____________________________________ Time: 07:51:57 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Re: New electrical architecture with ENGINE BUS At 12:29 PM 10/15/2013, you wrote: >A brass strap should NOT be used to connect the two battery negative >terminals together. The only thing connected to any battery terminal >should be soft flexible welding cable to reduce the risk of >vibration failure of the terminals themselves. A rigid brass strap >will transmit vibration from one battery to the other with the >possibility of breaking off the terminal on one or the other. > >Bob McC Agreed. I really like 4AWG welding cable for ALL battery jumpers irrespective of whether the rest of the fat wires are 4 or 2AWG. This stuff is very flexible and virtually incapable of putting vibration or other motion induced stresses on the lead posts or marginally sized machine screw battery terminals. Bob . . . ________________________________ Message 21 ____________________________________ Time: 07:56:18 PM PST US From: "Bill Bradburry" Subject: RE: AeroElectric-List: EXP 2 Bus workaround Bob, A friend of mine is running a Mazda engine on a test stand and is using a lot of the same controller, injectors, coils, etc that Fred is using. I asked him for some amperage load information and this is what he measured on his running engine: "I went out and measured the current requirements of the various systems on my Renesis test stand which has an EC2 and GM D585 ignition coils. System voltage was 15V with a battery charger attached and the CAS was driven to be equivalent to an engine RPM of 5000. When the EC2 is powered up, there are also a tach, 2 VDO temperature gauges, an O2 gauge, a voltmeter, and an electronic fuel pressure gauge powered as well. The results for the individual systems are: EC2 and gauges: 0.8 A 2 leading coils: 2.4 A 2 trailing coils: 2.4 A 2 primary injectors 0.7 A 2 secondary injectors: 0.7 A 1 Mazda stock RX7 fuel pump: 3.8 A Total in normal running config: 10.8 A The fuel pumps that RWS sold draw very close to the same current that the Mazda one does." This hopefully will shed some light on the load that Fred will be experiencing on his engine. Bill B _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: Tuesday, October 15, 2013 12:22 PM Subject: Re: AeroElectric-List: EXP 2 Bus workaround > How many pumps? My engine is designed to run on one pump; I have a back up pump as well; each pump has it's own filter; the back up is intended to handle failure or clogging of the first pump. The hi pressure pumps draw 5.7 amps each. Both pumps should be able to be energized by either battery...and...it seems to me that I should want to toggle switch from one pump to the other. Why all this layered 'redundancy'. Under what conceivable condition can you imagine that you'll be siting in the cockpit with a stumbling engine flipping switches to see what combination of positions gets the engine back? There are folks who make good money sifting BIG spreadsheets of numbers that speak to failure rates of individual parts for which (1) there are ESTABLISHED failure rate numbers . . . i.e., "This resistor, when used within these limits, has a CALCULATED failure rate of 3.8 x 10 to the minus 10. Meaning that if you really operated a large sample of such resistors until 99% of them are failed, you would get a bell shape curve of failures starting with some very tiny number failing in say 100 hours, and an equally tiny number failing in about 2X the calculated rate with a peak in the numbers at the calculated number. Now, take a constellation of such parts and build an electro-whizzy. Add all the effects of failures for the assembly and you get an Mean Time Between Failures number for the product. People who sit behind desks and write rules like to hang their hats on MTBF. . . and think they're doing a good and useful thing. In my experience, all this failure rate stuff is 99% smoke and mirrors. ALL machines flying electro-whizzies with MTBF numbers have things break every day. That's what keeps the mechanics employed. If a particular electro-whizzy shows a proclivity for failure at some number of hours much lower than predicted MTBF, do the folks behind the desks issue an AD and ground the fleet? No, those events go relatively un-charted assuming that (1) FMEA demonstrates that the failures do not put the airframe at risk and/or (2) the cost of added maintenance is insufficient to get the fleet operator's bean counters in a tizzy. So how does all this feathers and flooby-dust in the BIG airplanes guide our thinking for little airplanes? Easy. Easy, we do FMEA and then see how much cash is in your wallet. Let us assume that the gizmos you put in your airplane have a demonstrated MTBF of 500 hours. Terrible. That thing would never be allowed in the door at Boeing. But what's the significance of such dismal failure numbers? 500 hours of operation in the average light airplane is 10 years of service life. The 500 hour number suggests that about half of all such devices will have failed in 10 years. If that device is needed for continued flight, then what is the prudent prophylactic against bad-day-in-the- cockpit syndrome? Easy, install two of them. Hmmm . . . now what are the chances that BOTH devices would fail at the same time? Each device SHOULD be pre-flight tested. The maximum duration of the flight is on the order of 4 hours. So what is the likelihood of dual failure in that 4-hour window? What is the likelihood that failure of one pump will be teamed up with failure of a battery or the wiring and controls associated with that pump in that same 4-hour window? The pump is probably a vane style device driven by a brushed motor. The vulnerable components of this device are brushes, vanes and bearings. If all flights are normally conduced with the same pump, then wear-rate that attacks serviceability of the second pump is zero. This begs the question, "What value is added by multiple feed paths from multiple power sources to each pump?" That pump probably has a real MTBF on the order of 500 hours . . . yet there are many of them in service on airplanes. Dual fuel injectors? Seems unlikely. My engine is MPEFI; it has 4 fuel injectors...each one draws between 1 and 2 amps. Can you get us a resistance measurement of an injector coil? A fuel injector is opened for milliseconds once every other revolution of the crankshaft. So there are TWO values of significance to our deliberations. (1) PEAK current set by the coil resistance which drives wire sizing and noise issues and (2) AVERAGE current under most demanding engine operations. The second number is seldom articulated by engine suppliers in the OBAM aircraft industry. But this is the critical number for deducing ENERGY necessary to keep the engine running. Though I drove one years ago, (a '65 convertible), I have no idea how the conversion guys are setting it up. My engine has 4 coils...all together they draw 8 amps. My engine has dual electronic ignition thanks to (I believe) dual Hall effect sensors...I don't know what, if any, their current draw is. The same line of reasoning applies to ignition coils too. 2A per coil paints a picture of 24 watts being dissipated in each coil . . . a coil that is called upon to deliver millijoules (milliwatt-seconds) of energy to a plug every other revolution. Not a very efficient system. Klaus Savier's electronic ignition for a 6 cylinder engine draws 25 watts for ALL SIX plugs at max RPM. There's a disconnect here Will do...here's how I see it...to keep the prop spinning, I need: 1. The ECU (normal)...it has 3 power feeds...one for the "box" drawing 0.5 amps...one for the fuel injectors drawing 4 to 8 amps...and one for the coils drawing 8 amps (continuous...but engine guy sez during start up, draw could spike momentarily to 20 amps). Total continuous load: 16.5 amps. I am suspicious of those numbers for reasons cited. This engine guy would do well by his customers and himself to get some real instrumented numbers off of his product's electro-whizzies. If I were putting his engine on a TC aircraft, those numbers would be necessary. This isn't a whimsical demand unique to the certified aircraft market, it's fundamental to knowing how it works in any airplane. ECU (back up): It contains a duplicate motherboard accessed via a toggle switch on the control panel...no change in electrical load. 2. One serviceable fuel pump w/ an unclogged filter. Fuel pump draws 5.7 amps. Fuel pump (back up): I have a second pump (same rating as first) w/ separate filter. I BELIEVE that's all I need to keep the engine running...total load: 22.2 amps. (Round it up to say 25 amps?...what have I missed?) REAL numbers that I believe will prove to be much smaller. 250 Watts demand by an engine that's fitted with only 550 Watts of alternator seems out of whack. Are these engines flying now? What's the change that the supplier of this engine could be persuaded to get some real numbers off of a customer's airplane . . . or perhaps his own? If this electrical load for the engine is routed thru a (always hot?) battery bus, would we then want to tally up additional loads on an endurance bus as a back up to everything deemed essential which would be normally drawing from the EXP Bus in the event that the EXP fizzles? You're talking dual failure in the span of time needed to use all fuel aboard. The only reason you need to run the engine battery-only is if the alternator quits. If this were a Part 23 aircraft, we don't consider dual failures as part of the cert process. If the guys behind the desks don't worry about it . . . well . . . they're paid to worry. We get to do our own FMEA based mitigation of risk. And how do we provide the juice if the alternator fizzles as well? Note: regarding batteries: the Odyssey PC680 capacity is 16 ah, providing 24 "reserve minutes @ 25 amps"...see: http://www.odysseybatteries.com/mainpages/batteries.htm Assuming dual batteries and both battery states of 75%, I figure 24 ah available which would give 36 "reserve minutes" @ 25 amp draw. Does that sound right to you?...or am I getting way ahead of myself? Just a little . . . and if the numbers you've been offered are real, then alternator failure on your airplane would be an emergency situation. 30 minutes of battery-only endurance comes with severe pucker-factor. Are you really sure you want to fly this engine under that kind of risk? A rhetorical question at this stage of the design . . . I can't imagine an automotive manufacturer willing to toss off that kind of energy budget just to keep the engine running. I'll bet that engine in a car would run for hours on a good battery if all other loads were eliminated. Let's talk with your engine guy. Bob . . . ________________________________ Message 22 ____________________________________ Time: 08:04:27 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: diodes >I missed the original post, so I might not have all info needed for >a reply, but here goes: not having a diode across a relay's coil (as >purchased) is more the norm than the exception. Diodes for the job >described are dirt cheap (pennies, last time I checked) & available >anywhere you can buy electronic components. If the contactor does >what you need it to do, just add the diode. Don't 'replace' . . . modify. Diodes are cheap, readily available and non-critical as to electrical ratings. My personal favorites are the 1N540X SERIES devices where X can be any digit. Radio Shack will sell you two of these in a blister pak of two for about $2. See: http://tinyurl.com/n6wq2bx Everyone who claims to be in the electronics parts business will have them at similar or cheaper prices. These are all electrically VERY robust . . . smaller devices would suffice electrically. But they are mechanically robust too. Easier to work with and less subject to installer-damage. Here's a couple of articles on the topic . . . http://tinyurl.com/nva2xdy http://tinyurl.com/25wjo7w There's a lot of ol' mechanic's tales and hangar mythology about system spikes loose in the wild. If anyone encounters a convincing tale that give you the urge to spend more money or to rip out part of an existing system, let's talk about it here first. Bob . . . ________________________________ Message 23 ____________________________________ Time: 08:04:35 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: EXP 2 Bus workaround At 03:52 PM 10/15/2013, you wrote: >On Oct 15, 2013, at 9:22 AM, Robert L. Nuckolls, III wrote: > >> > How many pumps? >> >> My engine is designed to run on one pump; >> I have a back up pump as well; each pump has it's own filter; the >> back up is intended to handle failure or clogging of the first >> pump. The hi pressure pumps draw 5.7 amps each. Both pumps should >> be able to be energized by either battery...and...it seems to me >> that I should want to toggle switch from one pump to the other. >> >> Why all this layered 'redundancy'. Under what conceivable >> condition can you imagine that you'll be siting in the >> cockpit with a stumbling engine flipping switches to see >> what combination of positions gets the engine back? > >Bob...to answer your question, a clogged fuel filter is eminently >conceivable to me...to >provide a back up pump with separate filter seems fundemental...to >be able to switch from one pump to another seems straightforward enough. Okay, each pump has one switch closing a feed thru a fuse from one battery. Since you have two batteries, then standby pump from the main battery through one fuse and a switch, main pump from the engine battery through one fuse and a switch. Noting is gained by making offering dual power sources to each pump. >I'm simply mystified as to why you imply that "this layered >'redundancy' " would create rather than solve problems or confusion >if the engine starts sputtering. The more switches and switch positions multiplies possible combinations of operating conditions . . . EACH presenting a new endurance mode calculation. If your 20+ amps endurance numbers are real, then alternator failure is a TENSE condition no matter how many options there are. Likelihood of making a poor decision goes up with the square of tension. Liklihood of having a pump failure on top of an alternator failure is exceedingly remote and not generally considered in a Part 23 airplane. So this says a simple, totally independent substitute for a main pump that has failed for any reason is sufficient. Let's see what the real energy budget is and see what it takes to offer at least an hour of flight on batteries nearing end of service life. Bob . . . ________________________________ Message 24 ____________________________________ Time: 08:22:57 PM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: New electrical architecture with ENGINE BUS At 11:19 PM 10/14/2013, you wrote: > > > Attached is an electrical drawing with an ENGINE BUS. > >Joe, I know this has been addressed on the list before, but can you remind >me what software you use to produce such drawings? >\ TurboCAD will open, edit, save and print the AutoCAD drawings on my website. It will also import DXF files from other CAD platforms. The price is right too . .. http://tinyurl.com/kuj6vqx Another bargain is NanoCAD from this site. http://tinyurl.com/9yl3ug5 This is a freeware look-alike for AutoCAD. I don't have it installed on this machine but I did try it out about two years ago. Not a 100.0% clone for behavior but very close. The vast majority of "things" that are part of my AutoCAD habits embedded after 20 years played seamlessly on NanoCAD. The few hiccups were easily managed . . . it's a very intuitive program. Bob . . . ________________________________ Message 25 ____________________________________ Time: 08:22:57 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Re: Copper Foil width for VOR antenna At 04:26 PM 10/15/2013, you wrote: > >Thx... I am actually thinking of using the braid only as the antenna >material... as part of making a proper balun one would only use the >braid to connect to the antenna elements anyway while the center >cnnductor is not connected... this should avoid the problem you are >describing... as long as i can successfully slide about a 16" long >undisturbed braid-external shielding up on the stripped coax to >avoid the large resulting gap. > >Water will not get into this setup as it will be saturated with epoxy. The problem with embedded antennas is the potential for fatigue failure of the conductors if the composite structure flexes. This can produce hairline fractures in foil or wire antennas bonded to a composite surface. It can make your antenna conductors look like the wires in a strain guage . . . that stretch and compress as the surface responds to structure flexing. RF bandwidth of the wider foil is attractive but as mentioned here, insignificant with respect to performance. Consider an ALL COAX antenna assembly. Balun is optional . . . cool but performance difference is very small. Making the antenna elements from coax braid FLOATING INSIDE a piece of 1/4" Nylon tubing will get you a simple antenna material, adequate performance and the tubing isolates the antenna from structure so that flexing doesn't mechanically irritate the elements. 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