AeroElectric-List Digest Archive

Thu 10/13/05


Total Messages Posted: 8



Today's Message Index:
----------------------
 
     1. 05:17 AM - BAT contactor (Rodney Dunham)
     2. 05:42 AM - FW: Re: Controlling IR ND Alternators (Glen Matejcek)
     3. 06:02 AM - Re: BAT contactor (Ken)
     4. 05:02 PM - SD-8 noise levels (Robert L. Nuckolls, III)
     5. 05:29 PM - First Operational GQM Target Flight (Robert L. Nuckolls, III)
     6. 05:34 PM - Out of town until Thursday (Robert L. Nuckolls, III)
     7. 09:01 PM - Re: Controlling IR ND Alternators (Mickey Coggins)
     8. 09:01 PM - Re: Poor Man's Battery Capacity Tester (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 05:17:09 AM PST US
    From: "Rodney Dunham" <rdunhamtn@hotmail.com>
    Subject: BAT contactor
    --> AeroElectric-List message posted by: "Rodney Dunham" <rdunhamtn@hotmail.com> Battery contactor Bob or any protege :o) I built the SkyRanger2/Rotax912 without a battery contactor (Z-17 with minor mods) and installed a starter warn lamp. I'm nearing the point where I need to wire the Sonex/Jabiru3300. Will use Z-20 as my guide. The Sonex project came with a starter contactor bolted onto the firewall next to the BAT, starter contactor and VR. The space in there is quite limited and I'd rather mount an OV relay and condensor where the BAT contactor now lives. Other than getting the fat wires off the panel, it seems to me the only thing the starter contactor adds to the architecture is the ability to disconnect the starter in the event of a stuck (closed) starter contactor or starter sonlenoid. I guess I need to know just how likely is that? Also, with a starter warn lamp installed, will I get a hint prior to failure? If so, and since it happens at initial startup, ie on the ground, then I may forego the BAT contactor and simplify the architecture. What say you? On a related subject. In reviewing the Z drawings of my two dreams-come-true and checking wire size vs fuse size all of a sudden it hit me. The biggest fattest honker bolted directly to the battery has no fuse at all!!! Can someone tell me why I don't need one there? Is it that momentary cranking amps are so high that it would constantly blow fuses??? Rodney in Tennessee Sonex, Jabiru 3300 Dynon EFIS and EIS Becker (maybe MicroAir) radio and transponder The usual lights


    Message 2


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    Time: 05:42:16 AM PST US
    From: "Glen Matejcek" <aerobubba@earthlink.net>
    Subject: Re: FW: Re: Controlling IR ND Alternators
    --> AeroElectric-List message posted by: "Glen Matejcek" <aerobubba@earthlink.net> Hi OC- No problem; I'm glad to help if I can. > > A) If the incandescent idiot light is in series on the wire leading from the > switch to the alternator L terminal and the filament in the bulb breaks or > burns out then no current can get to the L terminal and the alternator shuts > down and stops providing electricity. Right? Is this the desired > arrangement? If so, why? That is how I understand the arrangement. It does seem peculiar that they would design a system where the failure of the light bulb would cause both the loss of power generation AND the loss of the associated warning. This has made me think of 2 things. First, it could be why there are relatively few alternators configured this way. Second, if one were to use LED for the idiot light, the odds of it failing would become remote in the extreme. Perhaps the automobiles equipped with this alternator do in fact have LED's. I don't know. > > B) On the other hand if one terminal of the idiot light is connected to some > normally hot aircraft bus and the other terminal of the idiot light is > connected to the L terminal a normally functioning light will be off as long > as the voltage at the two light terminals are equal. But the light will come > on when the L terminal is pulled to ground by the IR when the alternator > fails. Right? Isn't this the desired arrangement? Yes, this is how I understand the design to function. > > C) But what happens to the wire going from the switch to the L terminal, > which is carrying battery voltage and current, when the L terminal is pulled > to ground? Does that not create a direct short between the closed switch and > ground? Is the CB in the wire going from the switch to the L terminal there > to open in this situation? An astute observation. First, when the alternator is functioning properly, there is little or no actual current in that wire. The alternator just uses this line to sense voltage, much as an oil or fuel pressure line senses pressure without actually having fuel or oil flowing in that line. This lack of current flow is precisely why the idiot light does not illuminate under normal ops. The presence of the idiot light also means that there is no direct short in the automotive application when the 'L' terminal goes to ground. I have seen it suggested that if no light is used, an hundred ohm resistor should be substituted instead to keep the "alt inop" current reasonable. Also, a resistor in parallel with an incandescent bulb will allow the alternator to continue to function, even if the bulb should fail. I had considered letting the Alt field CB serve as an alternator failed indicator. The problem there is that if all the above assumptions are correct, every time I turn on the alt switch with the alt not turning, the CB will trip. This fact combined with the fact that MANY people have wired their alternators up according to Van's scheme without complaint leads me to believe that although the alternator takes the 'L' lead to ground, it still limits the current through that path. IE, although it goes to ground, it's not a dead short. I hope that explains more than it confused..... Glen Matejcek aerobubba@earthlink.net


    Message 3


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    Time: 06:02:40 AM PST US
    From: Ken <klehman@albedo.net>
    Subject: Re: BAT contactor
    --> AeroElectric-List message posted by: Ken <klehman@albedo.net> Hi Rodney There is background discussion in the archives on all this but here's my take on it. You may want to keep at least one contactor between the battery and the starter so you can indeed shut off a stuck on starter.. With magnetos I'd keep the battery contactor and toss the starter contactor. Some folks like to keep both though. With an electically dependant engine, I tossed the starter contactor. My starter current goes through the battery contactor. (Actually I wired my "battery" contactor so that it kills power to everything but leaves the alternator and ignition connected to the battery. That's just my choice and it is also discussed in the archives. My B lead (alternator) fuse and battery bus fuse blocks remain close to the battery.) Now I thought the Jabiru alternator used an eternal voltage regulator? If so then there is no need whatsoever for a OV contactor. With an Internal Regulator automotive type alternator some of us do use a OV contactor. As for the heavy battery wire, it is usually very short with the battery contactor beside the battery and there is nothing to be gained by trying to fuse it. In addition there is lots of comment about how fat wires installed properly almost never short or cause problems. If for some very unusual reason the heavy wire had to be long or in a precarious location then yes I'd add a current limiter but that would be a last resort. Ken Rodney Dunham wrote: >--> AeroElectric-List message posted by: "Rodney Dunham" <rdunhamtn@hotmail.com> > >Battery contactor > >Bob or any protege :o) > >I built the SkyRanger2/Rotax912 without a battery contactor (Z-17 with minor >mods) and installed a starter warn lamp. I'm nearing the point where I need >to wire the Sonex/Jabiru3300. Will use Z-20 as my guide. The Sonex project >came with a starter contactor bolted onto the firewall next to the BAT, >starter contactor and VR. The space in there is quite limited and I'd rather >mount an OV relay and condensor where the BAT contactor now lives. > > >Other than getting the fat wires off the panel, it seems to me the only >thing the starter contactor adds to the architecture is the ability to >disconnect the starter in the event of a stuck (closed) starter contactor or >starter sonlenoid. I guess I need to know just how likely is that? Also, >with a starter warn lamp installed, will I get a hint prior to failure? If >so, and since it happens at initial startup, ie on the ground, then I may >forego the BAT contactor and simplify the architecture. What say you? > >On a related subject. In reviewing the Z drawings of my two dreams-come-true >and checking wire size vs fuse size all of a sudden it hit me. The biggest >fattest honker bolted directly to the battery has no fuse at all!!! Can >someone tell me why I don't need one there? Is it that momentary cranking >amps are so high that it would constantly blow fuses??? > >Rodney in Tennessee > >Sonex, Jabiru 3300 >Dynon EFIS and EIS >Becker (maybe MicroAir) radio and transponder >The usual lights > >


    Message 4


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    Time: 05:02:38 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: SD-8 noise levels
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> A few days ago, someone asked if the SD-8 was capable of meeting DO160/M704 standards for system noise. I don't recall who it was and it took some time to dig out the traces I did on an SD8 some years ago. See: http://www.aeroelectric.com/articles/Alternators/SD-8/SD8_Noise_Plots.pdf These show the noise measured with various combinations of battery and sizes of filter capacitor across the SD-8's regulator output. The traces speak for themselves and show that the noise levels are quite benign and well inside Mil-Std-704 allowables. Bob . . .


    Message 5


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    Time: 05:29:34 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: First Operational GQM Target Flight
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> I'm still in contact with a number of the old missiles wiennies who went to CEI when our targets business was sold (the last of the skunk works left in Wichita aviation). Got some pictures in the mail today. The first non-experimental GQM-163 target was launched recently. This was my last really neat design task wherein I replaced a 6#, 200 cu-in, $6,000 relay based power distribution box with a 0.7#, 36 cu-in, $1,000 all solid state replacement. Here's a picture of the launch. http://www.aeroelectric.com/Pictures/Misc/1st_Operational_GQM.jpg The white thing on the back is a solid rocket booster that kicks the target up to better than M1.5 in about 5 seconds. The engines on the target are ram jets that need supersonic air coming in before they'll even run. After the booster falls away, the engines light off and the critter accelerates on up to M2.5. This sea-skimming (5M) hard maneuvering (10-12g's in any direction) target. It has a service life on the order of 3 minutes and covers about 100 miles of range. GPS and laser altimeter guided to hit an amazingly small box out in the target range where it gets shot at. Pretty rich stuff compared to chasing 30 year old rats out of Hawkers and Beechjets! Bob . . .


    Message 6


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    Time: 05:34:08 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Out of town until Thursday
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> Dee and I are packing up for the trip to Hamilton, Ontario where we'll deliver a weekend seminar on Saturday and Sunday. We're going to take a few extra days to wander the countryside before we come home so we'll be off line until Thursday. Bob . . .


    Message 7


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    Time: 09:01:05 PM PST US
    From: Mickey Coggins <mick-matronics@rv8.ch>
    Subject: Re: Controlling IR ND Alternators
    --> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch> > > A) If the incandescent idiot light is in series on the wire leading from > the > > switch to the alternator L terminal and the filament in the bulb breaks > or > > burns out then no current can get to the L terminal and the alternator > shuts > > down and stops providing electricity. Right? Is this the desired > > arrangement? If so, why? > > That is how I understand the arrangement. It does seem peculiar that they > would design a system where the failure of the light bulb would cause both > the loss of power generation AND the loss of the associated warning. This > has made me think of 2 things. First, it could be why there are relatively > few alternators configured this way. Second, if one were to use LED for > the idiot light, the odds of it failing would become remote in the extreme. > Perhaps the automobiles equipped with this alternator do in fact have > LED's. I don't know. > I asked the Denso people this question, and here is what they sent me: http://rv8.ch/files/DensoConnections.pdf Just for completeness, here is the contact info on the guy that sent me the file: David Yarus Assistant Manager Heavy Duty Aftermarket Department DENSO Sales California, Inc. (770) 565-6193 office (770) 565-7028 fax (678) 984-8353 cell CHECK US OUT ON THE WEB AT: Denso Heavy Duty Website (www.densoheavyduty.com) DAVID_YARUS "at" REMOVE-THIS-STUFFdenso-diam.com -- Mickey Coggins http://www.rv8.ch/ #82007 finishing do not archive


    Message 8


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    Time: 09:01:50 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Poor Man's Battery Capacity Tester
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 09:25 PM 10/11/2005 -0400, you wrote: >--> AeroElectric-List message posted by: "Rodney Dunham" ><rdunhamtn@hotmail.com> > >I'm about to build the PMBCT as per the 'Connection, page 2-9. > >I have purchased the following from Radio Shack; >1) Resistors... 470kOhm 1/2 watt, 5% tolerance (p/n 271-1133) >2) Zener Diode... INT4742A 12 Volt (p/n 276-0563) >3) DPDT Relay... 12VDC coil, 10A 112VAC contact voltage (p/n 275-0218) >4) Transistor... 2N3904 NPN silicon (p/n 276-2016) You need 470 ohm resistors, not 470K ohm . . . there's about 1:1000 difference. A 12v zener is too far removed from the 10v device called for. The other parts are okay. You could use two of the 1N4733 zeners from radio shack and hook them in series. They're rated at 5.1 volts each and would come close enough to behaving like a 10v zener. Let us know what kind of results you get! Bob . . .




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