Today's Message Index:
----------------------
1. 12:13 AM - Re: external power jack and crowbar OV module (Jim Jewell)
2. 01:01 AM - Re: external power jack and crowbar OV module (Werner Schneider)
3. 05:02 AM - Re: google conversion tool (CBFLESHREN@aol.com)
4. 05:30 AM - Re: external power jack and crowbar OV (Robert L. Nuckolls, III)
5. 05:42 AM - Re: Current Limiters (Robert L. Nuckolls, III)
6. 05:56 AM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III)
7. 07:33 AM - Alt Field question (Scott Bilinski)
8. 07:52 AM - Fastons (Eric M. Jones)
9. 07:57 AM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III)
10. 07:59 AM - Re: Current Limiters (Robert L. Nuckolls, III)
11. 10:00 AM - Re: BUS / Fuse Blocks (Rick Caldwell)
12. 10:17 AM - Re: BUS / Fuse Blocks ()
13. 11:46 AM - Re: wiring Nova and Aeroflash strobe/nav/pos lights (Joa Harrison)
14. 12:00 PM - Aircraft Configuration Spreadsheet (Pete Waters)
15. 12:44 PM - landing/taxi lights (Carlos Sa)
16. 02:56 PM - Re: landing/taxi lights (Matt Prather)
17. 02:58 PM - Inductive current measuring device .... (Jim Sower)
18. 03:14 PM - Re: landing/taxi lights (Carlos Sa)
19. 03:46 PM - Run away alternator scenario (BAKEROCB@aol.com)
20. 04:27 PM - Inductive current measuring device .... (Eric M. Jones)
21. 04:52 PM - Re: Current Limiters (Ernest Kells)
22. 05:00 PM - Re: Ground Loop (MikeM)
23. 05:03 PM - coax terminations and grounding a pusher (Alex Balic)
24. 05:59 PM - Re: wiring Nova and Aeroflash (Robert L. Nuckolls, III)
25. 06:04 PM - Re: coax terminations and grounding a pusher (Robert L. Nuckolls, III)
26. 06:06 PM - AMP / Cannon Connectors (David Schaefer)
27. 06:15 PM - Re: Current Limiters (Robert L. Nuckolls, III)
28. 06:23 PM - Fw: Reply from Nova Re: Installation Diagrams (Robert L. Nuckolls, III)
29. 06:32 PM - Re: Current Limiters (Matt Prather)
30. 07:12 PM - Re: Aircraft Configuration Spreadsheet (George)
31. 07:53 PM - Re: Run away alternator scenario (Robert L. Nuckolls, III)
32. 09:16 PM - Re: Fw: Reply from Nova Re: Installation Diagrams (Joa Harrison)
33. 09:35 PM - Fuse Holders (Kingsley Hurst)
Message 1
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| Subject: | Re: external power jack and crowbar OV module |
--> AeroElectric-List message posted by: "Jim Jewell" <jjewell@telus.net>
Hi Werner,
Since the people at B&C changed their site layout things are hard to find,
go to
http://www.bandcspecialty.com/cgi-bin/ez-catalog/cat_display.cgi?26X358218
Scroll down the page about 3/4 and you will find what you are seeking.
Try putting a solar cell type charger on your battery, it should help some.
Lots of luck,
Jim in Kelowna
----- Original Message -----
From: "Werner Schneider" <wernerschneider@compuserve.com>
Subject: AeroElectric-List: external power jack and crowbar OV module
> --> AeroElectric-List message posted by: "Werner Schneider"
<wernerschneider@compuserve.com>
>
> Can somebody please help me.
>
> During this very cold time in Switzerland I get troubles with my 17Ah
> Panasonic, if the engine starts not at the first time, or if the plane
sits
> for several weeks. So I'm going to fit the Piper/Cole Hersee connector.
>
> I've searched yesterday through the Bob's site as well as the B and C site
> but could not find the crowbar OV module as a part.
>
> Is this module not available as a part, or did I just miss it?
>
> Many thanks for pinpointing
>
> Werner
>
>
Message 2
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| Subject: | Re: external power jack and crowbar OV module |
--> AeroElectric-List message posted by: "Werner Schneider" <wernerschneider@compuserve.com>
Hello Jim,
thanks for the help, exactly what I've searched for, I did search everywhere
(would have expected to see it close to the regulators) but have overseen it
in the MISC section. A sercah function would help a lot.
I've copied todd to let him know.
Many thanks
Werner
----- Original Message -----
From: "Jim Jewell" <jjewell@telus.net>
Subject: Re: AeroElectric-List: external power jack and crowbar OV module
> --> AeroElectric-List message posted by: "Jim Jewell" <jjewell@telus.net>
>
> Hi Werner,
>
> Since the people at B&C changed their site layout things are hard to find,
> go to
> http://www.bandcspecialty.com/cgi-bin/ez-catalog/cat_display.cgi?26X358218
> Scroll down the page about 3/4 and you will find what you are seeking.
> Try putting a solar cell type charger on your battery, it should help
some.
>
> Lots of luck,
>
> Jim in Kelowna
>
>
> ----- Original Message -----
> From: "Werner Schneider" <wernerschneider@compuserve.com>
> To: <aeroelectric-list@matronics.com>
> Subject: AeroElectric-List: external power jack and crowbar OV module
>
>
> > --> AeroElectric-List message posted by: "Werner Schneider"
> <wernerschneider@compuserve.com>
> >
> > Can somebody please help me.
> >
> > During this very cold time in Switzerland I get troubles with my 17Ah
> > Panasonic, if the engine starts not at the first time, or if the plane
> sits
> > for several weeks. So I'm going to fit the Piper/Cole Hersee connector.
> >
> > I've searched yesterday through the Bob's site as well as the B and C
site
> > but could not find the crowbar OV module as a part.
> >
> > Is this module not available as a part, or did I just miss it?
> >
> > Many thanks for pinpointing
> >
> > Werner
> >
> >
>
>
Message 3
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| Subject: | Re: google conversion tool |
--> AeroElectric-List message posted by: CBFLESHREN@aol.com
< Some of you probably already know this but Google has a feature for doing
unit conversions that is *very* slick. Highly case and syntax insensitive so
it's easy to use. Check it out.
http://www.google.com/help/features.html#calculator
And for those that have not heard of this great FREE Conversion Download see
this, less than 5 kilobyte jewel:
http://www.joshmadison.com/software/convert/dl.asp
Chris Fleshren
Message 4
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| Subject: | Re: external power jack and crowbar OV |
module
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
module
At 07:40 AM 10/28/2003 +0100, you wrote:
>--> AeroElectric-List message posted by: "Werner Schneider"
><wernerschneider@compuserve.com>
>
>Can somebody please help me.
>
>During this very cold time in Switzerland I get troubles with my 17Ah
>Panasonic, if the engine starts not at the first time, or if the plane sits
>for several weeks. So I'm going to fit the Piper/Cole Hersee connector.
>
>I've searched yesterday through the Bob's site as well as the B and C site
>but could not find the crowbar OV module as a part.
>
>Is this module not available as a part, or did I just miss it?
>
>Many thanks for pinpointing
It's 3/4 of the way down the page at
http://www.bandc.biz/cgi-bin/ez-catalog/cat_display.cgi?26X358218
Bob . . .
Message 5
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 05:13 PM 10/27/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Ernest Kells"
><ernest.kells@sympatico.ca>
>
>I have a large capacity Precision alternator (installed) that I would like
>to limit for a basic VFR-only RV-9A.
>
>I have installed the Vans 40 amp shunt. I notice that the smallest current
>limiter in the B&C catalogue is also 40 amps (C905-40). I was looking for
>about 35 amps so as to not having any nuisance problems.
>
>Is this a problem? I don't want to risk blowing the Vans 40 amp shunt. The
>extra amps would be a nice cushion for the seat heaters and that initial
>load on the pitot tube heater.
>
>This seems safe - but I want to be certain. Thanks for any help.
The shut's rating has more to do with calibration than with
maximum allowable current limits. The ANL "limiters" are just
really robust fuses and you use them to protect wires from
hard faults. In this case, shorted diodes in the alternator
are highest risk (although quite small with modern alternators)
fault potential. The selection of a limiter has almost no
relationship with the size of you ammeter shunt and no relationship
for "protecting" it.
What is the capacity of your alternator? You cited "large capacity"
but with no number to tell us what "large capacity" means.
Bob . . .
Message 6
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| Subject: | Re: wiring Nova and Aeroflash |
strobe/nav/pos lights
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
strobe/nav/pos lights
At 01:54 PM 10/27/2003 -0800, you wrote:
>--> AeroElectric-List message posted by: Joa Harrison
><flyasuperseven@yahoo.com>
>
>
>I seem to recall a schematic for cleanly (noise wise) wiring the Nova
>supplies using the foil shielded triple wire they supply but can't seem to
>find it, can someone refresh my memory?
>
>Trying to find the cleanest way to do something with the drain wire and
>also suggested wire sizes going out to the nav/pos lights (do I really
>need an independent ground to the single point firewall ground or will a
>twisted pair work?).
Extend the drain wire with a pigtail of 22 or 20AWG wire and
ground to mounting screws that hold power supply on your airplane.
If airplane is metal, ground power supply locally to airframe.
If composite, a parallel route pair taken to vicinity of single-point
ground is good . . . then break out (+) wire to continue on
to strobe switch.
Bob . . .
Message 7
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| Subject: | Alt Field question |
--> AeroElectric-List message posted by: Scott Bilinski <bilinski@kyocera-wireless.com>
I have the crowbar OV module and relay installed and just found a possible
problem. I was doing a engine run up and tried to turn on the Alt Field, It
would not turn on. On the next engine run up I turned the field on before
engine start and everything is fine. If the Alt Field breaker pops for what
ever reason I will not be able to reset it in flight. Is this normal?
Unfortunately I followed the Van's wiring before I got turned onto the Aero
Electric book.
Scott Bilinski
Eng dept 305
Phone (858) 657-2536
Pager (858) 502-5190
Message 8
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--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
Bob (et al),
I've read your various epistles on Fastons and I fully agree. My experience
is that the Faston to quick-fit connections are superior in many ways to
most other fastening methods.
I do a lot of design with Fastons and Mosfets that invariably leads to the
issue of how much current a female Faston and the mating pcb "quick-fit"
terminal is rated for. Info is hard to come by.
My presumption is -- if Fastons are sold in AWG 10 sizes-- then it is only
reasonable that the proper quick-fit terminal should be assumed to carry the
rated AWG 10 ampacity. (Which depends more on the wire insulation melting
point than anything else.)
Aye???
Good reference on
ampacity---http://www.allaboutcircuits.com/vol_1/chpt_12/3.html
(Faston is a trademark of Aircraft & Marine Products).
Regards,
Eric M. Jones
www.PerihelionDesign.com
113 Brentwood Drive
Southbridge MA 01550-2705
Phone (508) 764-2072
Email: emjones@charter.net
For every complex problem, there is a solution that is simple, neat, and
wrong.
- H. L. Mencken
Message 9
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| Subject: | wiring Nova and Aeroflash |
strobe/nav/pos lights
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
strobe/nav/pos lights
>
>Twisted pair isn't designed to reduce radiated noise. The conductors don't
>actually block one another from transmitting, at least not much. You need
>coaxial, or some other type of surround-shielding for that. (How that
>works is a Physics question, pick up any Electricity and Magnetism text
>for a lecture on one of the more boring aspects of electricity, unless you
>love math.)
Actually, noise propagation modes are equal in both directions. A single
strand of wire in space has the same ability to radiate noise as it does
to pick it up. The only difference between the wire's role in a noise
problem is whether it carries signals of a potential victim system
or antagonist system.
So, twisting is a good thing to do to ward off noises that propagate
MAGNETICALLY while shielding puts a muzzle on ELECTROSTATIC dragons.
>Back to your original questions:
>1. B&C sells foil shielded three-wire cable. Unfortunately, nothing larger
>than 22AWG, so check the power requirements for your lights.
B&C's shielded wires are braided and yes, they are 22AWG. Members
on the list have reported good results with substituting this
wire for the fatter Beldfoil, PVC insulated wire shipped with
most strobe kits. Also, within the last few weeks, someone posted
a mail-order source for the Beldfoil wire by the foot. I'd appreciate
a repeat post. I'll file it away in a more accessible location.
>2. Connect the drain wire to ground on ONE END of the cable (preferably at
>a single-point ground near the battery).
I doubt that any installation manual for a strobe system has
suggested extending the shield this far. It's designed to carry
VERY TINY currents generated by capacitive coupling between
bundles and can be taken to any convenient local ground . . . for
strobes this is usually case ground at the power supply's mounting
bolts.
Are you in possession of installation instructions for the Nova
system? What do they show?
Bob . . .
Message 10
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:43 PM 10/27/2003 -0700, you wrote:
>--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
>
>
>I might not understand your question exactly, but I think you
>are asking whether the shunt can be damaged by running too much
>current through it. . . .
<snip>
> . . .its probably still
>okay, and 4W (that's 80A) might be okay with the shunt too, though
>Amperage readings might get a little wacky because of heating.
>
>So, I don't think you need a current limiter to protect the shunt,
>though you may want one for other design considerations.
>
>Hope that helps.
A well crafted answer sir. Thank you.
Bob . . .
Message 11
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| Subject: | Re: BUS / Fuse Blocks |
--> AeroElectric-List message posted by: "Rick Caldwell" <racaldwell@hotmail.com>
David,
My RV-6 has a sliding canopy so the bulkhead behind the panel is where I
mounted the fuse blocks. Since I have the RMI uMonitor, I had space left in
the panel for a nice sized storage box on the right side. I made the rear
wall of the box a door that swings out for access to the fuses.
Rick Caldwell
RV-6 136RC
One Design 137RC
>Where are the RV6 / 7 builders putting the primary and secondary fuse
>blocks in the aircraft? I'm having a difficult time finding room for
>the two regulators and fuse blocks and need some creative help.
>
>Regards,
>
>David
>RV6-A (wiring)
Add MSN 8 Internet Software to your current Internet access and enjoy
patented spam control and more. Get two months FREE!
Message 12
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| Subject: | Re: BUS / Fuse Blocks |
--> AeroElectric-List message posted by: <racker@rmci.net>
On my -6 slider, I have a hinged panel mounted between the instrument
panel and first bulkhead. The hinge is at the bulkhead, allowing the
panel to swing down after removing the knobhead screw/nutplate securing it
at the panel.
Main fuse block is mounted to this panel, easy to service. Secondary
block (always hot) is mounted on the topmost portion of the firewall
recess. Pic on request if my explanation is confusing <g>.
Rob Acker (RV-6 flying)
do not archive
> Where are the RV6 / 7 builders putting the primary and secondary fuse
> blocks in the aircraft? I'm having a difficult time finding room for
> the two regulators and fuse blocks and need some creative help.
>
> Regards,
>
> David
> RV6-A (wiring)
Message 13
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| Subject: | wiring Nova and Aeroflash strobe/nav/pos lights |
--> AeroElectric-List message posted by: Joa Harrison <flyasuperseven@yahoo.com>
The Nova instructions aren't the best and don't even show connections to the strobes,
only to the unit.
Here's the instructions neverless...
http://www.strobe.com/pdfs/eps40X-install.pdf
Joa
++++++++++++++++++++++++++++++++++++++++++++++
Are you in possession of installation instructions for the Nova
system? What do they show?
Bob . . .
---------------------------------
Exclusive Video Premiere - Britney Spears
Message 14
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| Subject: | Aircraft Configuration Spreadsheet |
chaskuss@bellsouth.net, Hebeard2@aol.com, lhelming@sigecom.net,
aletherington@rogers.com, VE3LVO@rac.ca
--> AeroElectric-List message posted by: Pete Waters <pedroagua@yahoo.com>
Here y'all go. This is very rough right now; I'd say on the scale of Version
1.0 and Version 2.0, it's more like Version 0.5. But you get the idea.
I'm also thinking of making, in PowerPoint or something like that, a paper block
diagram of the airplane. It could be hyperlinked to the spreadsheet entries,
so, fo example, if you clicked ont he "alternator" box on the block diagram,
it would lead you to the entry in the spreadsheet. Also, vice-versa, from
spreadsheet to block diagram.
All in all this will involve a lot of mouse-clicking, and may be way too anal-retentive,
but I think it's the best way to organize one's thoughts about the
complex beasts that we're building and flying. I'm not smart enough to keep
it all straight in my head.
If anybody else wants a copy let me know.
Pedro
---------------------------------
Exclusive Video Premiere - Britney Spears
Message 15
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| Subject: | landing/taxi lights |
--> AeroElectric-List message posted by: Carlos Sa <carlosfsa@yahoo.com>
Hello, listers
Does anyone have URL to headlights technical specifications?
I have one 7610 and one 7606 (sealed beam halogen, round) that I was thinking on
installing in the
wings of my CH601, but noticed that many RVs use the MR-16. Wonder how they (and
others, like JC
Whitney's 88ZX9844X, http://www.aeroelectric.com/temp/4352.JPG , etc.) compare??
Any pointers?
Thanks in advance
Carlos Sa
Montreal, Canada
Ch601-HD, plans
Message 16
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| Subject: | Re: landing/taxi lights |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Sylvania (among others) makes replacements for all of the standard
halogen sealed beam headlamps. Information can be found here. Most
of these lamps can be found in the automotive section at Walmart.
http://www.sylvaniaautocatalog.com/sylvania/sealedbeams.asp#
Regards,
Matt-
N34RD
> --> AeroElectric-List message posted by: Carlos Sa <carlosfsa@yahoo.com>
>
> Hello, listers
>
> Does anyone have URL to headlights technical specifications?
>
> I have one 7610 and one 7606 (sealed beam halogen, round) that I was
> thinking on installing in the wings of my CH601, but noticed that many
> RVs use the MR-16. Wonder how they (and others, like JC Whitney's
> 88ZX9844X, http://www.aeroelectric.com/temp/4352.JPG , etc.) compare??
>
> Any pointers?
>
>
> Thanks in advance
>
>
> Carlos Sa
> Montreal, Canada
> Ch601-HD, plans
>
>
Message 17
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| Subject: | Inductive current measuring device .... |
--> AeroElectric-List message posted by: Jim Sower <canarder@frontiernet.net>
When I was in the auto repair business (long ago in another life) there were
inductive current measuring devices that clamped over, say, an alternator B+
lead and measured output pretty accurately. I don't want to run an extra 10'
run of wire just to have an ammeter. I would prefer to have a pickup on the B+
cable just before the Alt-Mstr wired to the panel with 24 awg. Then I could
wire the other side of Alt-Mstr to battery and one long line to the buss' up
front.
Needs to be very affordable, moderately accurate and easy to install ... Jim S.
Jim Sower
Crossville, TN;
Long-EZ N83RT, Velocity N4095T
Message 18
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| Subject: | Re: landing/taxi lights |
--> AeroElectric-List message posted by: Carlos Sa <carlosfsa@yahoo.com>
Matt, thanks for the input.
I had searched the Osram-Sylvania site, as well as the GE site ( http://catalog.gelighting.com ),
but I only found mechanic and electrical specs.
What I'd like is to get photometric data (a luminous intensity polar graph would
do) and see how
these different products compare.
Cheers
Carlos
do not archive
--- Matt Prather <mprather@spro.net> wrote:
> Sylvania (among others) makes replacements for all of the standard
> halogen sealed beam headlamps. Information can be found here. Most
> of these lamps can be found in the automotive section at Walmart.
>
> http://www.sylvaniaautocatalog.com/sylvania/sealedbeams.asp#
>
> Regards,
>
> Matt-
> N34RD
Message 19
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| Subject: | Run away alternator scenario |
--> AeroElectric-List message posted by: BAKEROCB@aol.com
10/28/2003
Hello Bob Nuckolls, Below is a copy of a previous posting on the list. Can
you please comment on the validity of this scenario and the proposed solution?
Thank you.
'OC' Baker, Builder of KIS TR-1 #116 4/14/97 - ?/?/?
----------------------COPY OF 03/29/03 POSTING
FOLLOWS----------------------------------
<<From: "Mike Lehman" <LehmansMtl@netzero.com>
Subject: AeroElectric-List: Alternator Systems
...................SKIP...............We've got an external voltage regulator
powered via a 5 amp field supply breaker. However, virtually all light
aircraft then power the field breaker from the battery side of the 'B' lead
fuse/breaker (typically 40 to 60 amps rating).
If this main breaker/fuse opens, the VR senses low voltage and maximizes
alternator
field current in the impossible attempt to restore 13.8 to 14.5 volts on
the disconnected buss. The result is 100+ volts at the alternator B terminal
and sometimes severe alternator damage involving the faults mentioned. In my
opinion, the field supply breaker should be powered from the alternator side
of the main breaker. Regards, Mike>>
Message 20
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| Subject: | Inductive current measuring device .... |
--> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net>
>there were inductive current measuring devices that clamped over, say, an
alternator B+
>lead and measured output pretty accurately.
>Jim Sower
Jim, It used a hall effect sensor (for AC you can use a clamp-on
transformer...) There aren't many ways to do this job, but this looks like a
good one. See these guys.
http://www.allegromicro.com/hall/currentsensor.asp
Eric
Message 21
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Ernest Kells" <ernest.kells@sympatico.ca>
Bob, Matt and others:
Let me state my question with a little more info - I basically don't even
know the question but I think I need to understand this now. I am using
your Z-2 diagram with the always hot bus.
I have a large Prestolite alternator (installed) that I would like to limit
for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to keep the
alternator. It is a tight fit - but it does fit. Note: almost all work -
engine with all appliances and prop hardware, cowling, wiring, heat shields,
etc., are finished. Change at this stage is not easy. I have installed the
Vans 40 amp shunt, wire, busses, etc., based upon an overall 40 amp design.
Matt Prather stated "I might not understand your question exactly, but I
think you are asking whether the shunt can be damaged by running too much
current through it........."
That's my question! But his beautiful answer just confuses me. All I know
is that I have a voltage regulator and OVM to limit the voltage. It seems
like I should have a mechanism to limit the amperage output from 70 to no
more that 40 amps. The only "mechanism" I have in the electron stream is a
40 amp shunt (a piece of Bakelite with a flat bar). Do I just need a simple
35 or 40 fuse/circuit breaker on the main bus (#8 wire from battery
contactor) ???
Thanks for any help in knocking down this mental block.
Ernest Kells - RV-9A O235-N2C, Wood Prop
90 plus % Complete - electrical
Message 22
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--> AeroElectric-List message posted by: MikeM <mladejov@ced.utah.edu>
> From: "Michel RIAZUELO" <mt.riazuelo@wanadoo.fr>
> I have heard about "ground loop". Who can tell me more or
> indicate where are the things I have to read ?
Michel,
In the context of airplanes, the goal when installing radios,
intercoms, and entertainment systems is to NOT hear alternator
whine, strobe squeal, electric gyro brush noise, and magneto
pulses in your headphones (or have others hear these noises in
your radio transmissions). An installation which has the audio
contaminated with these undesirable noises is said to have
"ground loops" (the most likely cause), while one where the
audio is "clean" does not.
In most metal airframes, the airframe itself is used as a
conductor for the minus side of the power distribution. Each
device has a short minus wire which is grounded locally, or some
devices (like strobe power packs) ground through the case. In
non-metallic airframes, you have to explicitly run minus supply
wires to these remote devices.
You get to choose if each of these runs all the way back to the
battery minus terminal (radial grounds), or if you run a heavy
ground bus from the battery minus terminal, and then ground the
remote devices to this (ground tree). As far as keeping noise
out of the audio, the former is preferable, but not absolutely
required. In a metal airframe, you don't get that choice.
If the current flowing to/from these remote devices happens to
have frequency components in the audible range (alternator
ripple, strobe power supply, gyro brushes, magneto Primary
leads), and there is some way for these currents to "couple"
into the audio wiring, then you would hear the noise mixed with
whatever audio you are listening to... The goal when installing
is to prevent "coupling" between the noise currents and the
audio system.
Both airframes and copper ground trees are slightly resistive,
and the current flowing to/from the various devices causes a
voltage drop along the airframe/ground tree wiring. In a well
designed ground distribution system, the ground drops may be
only a few tens of milliVolts (mV), but that is enough to
contaminate the audio if these drops are allowed to "couple"
into the audio wiring. In the worst case, the ground drops might
be as high as hundreds of mV.
A bad example of this is in my Cessna 182, where a 60A
alternator is mounted on the engine, and the battery is mounted
in the aft end of the fuselage (for weight distribution). The
alternator puts out 60A of audible ripple current, which flows
from the ground stud of the alternator, through the ground strap
to the engine crankcase, through the engine, through another
ground strap across the rubber engine mount to the motor mount
cradle, to the fire wall, along the fuselage under the cabin
floor to the aft fuselage, to the battery ground strap,
and finally into the minus terminal of the battery.
Imagine taking two very long clip leads; connect one to the
alternator frame, and the other to the battery minus terminal.
Bring the other two ends of the clip leads into the cabin, and
connect them to the tip and barrel of a standard aviation
headset which you are wearing. Now start the engine and make
sure the alternator is charging.
The total ground voltage drop between the clip leads (alternator
all the way to the battery minus) will be plainly audible in the
headset. Obviously, the ground drop is large enough to create a
voltage signal level almost as big as what would normally be
driving the headsets.
So how do you prevent the noise sources from "coupling"
into the audio system? Some people think that the coupling is
inductive or capacitive, and that "shielding" is key to
eliminating contaminated audio. Others think that "filtering"
the noise sources is the key, but both of these methods are
only secondary, and rarely fix the underlying problem.
The primary cause of audio contamination is allowing the audio
system to connect to the airframe power ground (or ground
wiring) at more than ONE location (violating the principle of
"single point ground"). If the audio system connects into the
current carrying ground system at multiple places ("ground
loop"), the ground voltage drops that exist between the multiple
grounding points can add in series with the audio signals, just
like the clip leads/headphone test above.
Mic audio level is only a few hundred mV, so it is easy to
get a few tens of mV of alternator ripple between the radio
stack and the airframe point where the mic jack is "grounded" if
you don't take steps to prevent the mic jack sleeve from coming
in contact with the airframe.
The correct way to wire your audio is to have a completely
separate ground wire between each disparate audio item, and then
cross tie this whole "floating audio ground" to the airframe (in
a metal airframe) or to the power ground bus (in a non-metallic
airframe) in just exactly ONE place... This avoids having the
power ground drops appearing between a radio output and its
headphone jack, for example.
This requires some mechanical ingenuity. For example, when
mounting mic and headphone jacks, you have to use insulating
shoulder washers to keep the threaded sleeve from touching the
airframe. Since they are not locally grounded, an additional
ground wire from each jack has to run back to the intercom/audio
panel... Usually, I use shielded wire for all of the jack
wiring, where the shield is used for the jack sleeves, and the
conductors inside are used for PTT, Mic Tip, R and L headphone.
Okay, so we now understand "single point ground", but what
happens in the radio stack? It turns out that all of the
standard avionics (King, Garmin, UPSat, Narco, uAir) connects
the audio and power grounds internally to the case of each
radio, which contacts the tray, which is grounded by virtue of
the rack being fastened into the rails in the panel, which is in
turn connected to the airframe structure. You get no choice
about this, you are stuck with it, especially in a Cessna or
Mooney. If you are creating the panel yourself, then maybe you
can control things.
When installing your radios/audio panel into a metal aircraft,
the radio rack stack becomes the defacto single point ground for
the entire audio/avionics suite. When you make your audio wiring
harnesses, you have to take this into consideration. The best
you can do is not allowing any of the remotely mounted parts of
the audio system from contacting the airframe locally. This is
why the cabin speaker needs to have two wires running from it to
the audio panel, one of which is grounded at the rear of the
audio panel. Why each mic and headphone jack brings its sleeve
all the way to the rear connector of the audio panel/intercom,
etc, etc.
In a non-metallic airplane, you could use the instrument panel
as a ground plane for all of the radios/audio stuff, and
purposefully keep the alternator and strobe currents out of the
panel area. Don't ground the electric gyros to the panel (ie run
the gyro minus lead more directly to the battery minus).
This raises some interesting problems. For example, suppose you
have a nice clean audio system (no whine or squeals), and you
want to add a CD player/AM/FM entertainment system that you want
to power from the aircraft power. Your stack is full, so you
have to mount the CD system someplace else, like in the center
console. The CD system has an "audio ground" and it has a "power
ground" pin. Where do you tie these?
First, take an Ohmmeter, and measure between the CD system's
audio and power ground pins, and the case. There is a 99%
probability that the cheapskate who designed it tied both of
these to the CD system's case, which poses the following
dilemmas:
When you screw the CD system into the console (assuming a metal
mounting structure), for better or worse, you have now tied the
CD system to a ground removed from the one that the rest of all
your radio stack is tied to. If there is a big preexisting
ground drop in the airframe between the radio stack and the
center console, then you are screwed, because there is nothing
you can two with the as yet unconnected CD system audio
and power ground wires which will undo this.
The only hope is to "isolate" the CD system by using some sort
of insulating mounting which keeps it from grounding through its
case. Now you still have two "ground" wires to hook up. The only
place where these can be connected without violating the "single
point ground" for the entire audio system is to tie the power
ground to the rails of the radio rack (same place as where the
radios are presently grounded), and tie the audio ground to the
audio panel. Space permitting, you are way better off mounting
the CD system in the center radio stack where it doesnt matter
if its case touches the rails.
So, in summary: When wiring a metal airframe, use the airframe
as the ground return path for all non-audio stuff. Mount all of
your radios/audio panel/intercom/entertainment in the radio
stack. Connect the power grounds from all the avionics to a
single point electrically connected to the rack assembly.
Connect all of the audio grounds to the rear of the audio
switching panel. Tie all sleeves from remotely-mounted isolated
mic/headphone jacks to the intercom which in turn should be
grounded only to audio switching panel. Any other piece of audio
equipment should be "floated" locally, its power ground tied to
the radio racks, and its audio ground brought up to the
switching panel.
When wiring a non-metallic airframe, connect all of the
non-audio stuff to a network of ground wires where ultimately
each item has a path back to the minus terminal of the battery.
Since some of these paths may be shared, the current carrying
capacity of the ground wires has to be considered. When wiring
all of your avionics/audio items, tie all grounds (both power
and audio) to a single point located on or near the radio
rack(s). Tie just ONE single jumper wire from the radio grounds
to the power ground bus.
Mike Mladejovsky, PhD EE
Skylane '1MM
Pacer '00Z
Message 23
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| Subject: | coax terminations and grounding a pusher |
--> AeroElectric-List message posted by: Alex Balic <alex157@direcway.com>
I am trying to attach some connectors to my RG59 coax- the connectors come
with 3 pieces- the body which fits over the inner insulator (and possibly
under the outer sleeve), the conductor tip, and the crimp sleeve. Although
the sleeve fits over the cable easily, it won't even come close to fitting
over the cable sheath/connector body, after the body is inserted into the
cable end- is this supposed to be assembled by removing the jacketing
leaving only the braid, and crimping that down to the body? it would seem
that that would be a weaker system than leaving the jacketing on, but
really, it doesn't even come close to sliding over once the body is
inserted- am I missing something here? I looked in the book, but all of the
connector types there use threaded connectors, which I can go and get too I
suppose, but I have these on hand.
Also, about the grounding , it is mentioned that a composite pusher aircraft
leads to ground loops on the engine instruments, but I could not find a good
solution to this presented other than increasing the wire diameter- I have a
ground through the firewall, and will have a second in the front- which
could come directly from the battery, and not have to come to the front from
the rear ground - is this correct? I don't want to have a problem with the
indications on my instruments...
Message 24
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| Subject: | wiring Nova and Aeroflash |
strobe/nav/pos lights
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
strobe/nav/pos lights
At 11:46 AM 10/28/2003 -0800, you wrote:
>--> AeroElectric-List message posted by: Joa Harrison
><flyasuperseven@yahoo.com>
>
>
>The Nova instructions aren't the best and don't even show connections to
>the strobes, only to the unit.
>
>Here's the instructions neverless...
>
>http://www.strobe.com/pdfs/eps40X-install.pdf
Okay, I just dropped them a note to ask what their
recommendations were with respect to shield grounds.
Bob . . .
Message 25
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| Subject: | Re: coax terminations and grounding a pusher |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 06:59 PM 10/28/2003 -0600, you wrote:
>--> AeroElectric-List message posted by: Alex Balic <alex157@direcway.com>
>
>I am trying to attach some connectors to my RG59 coax-
RG59???? this is television coax . . . 75 ohm, I'd hope you
were dealing with RG-58 and better yet, RG-400
>the connectors come
>with 3 pieces- the body which fits over the inner insulator (and possibly
>under the outer sleeve), the conductor tip, and the crimp sleeve. Although
>the sleeve fits over the cable easily, it won't even come close to fitting
>over the cable sheath/connector body, after the body is inserted into the
>cable end- is this supposed to be assembled by removing the jacketing
>leaving only the braid, and crimping that down to the body? it would seem
>that that would be a weaker system than leaving the jacketing on, but
>really, it doesn't even come close to sliding over once the body is
>inserted- am I missing something here? I looked in the book, but all of the
>connector types there use threaded connectors, which I can go and get too I
>suppose, but I have these on hand.
See http://www.aeroelectric.com/articles/bnccrimp.pdf
>Also, about the grounding , it is mentioned that a composite pusher aircraft
>leads to ground loops on the engine instruments, but I could not find a good
>solution to this presented other than increasing the wire diameter- I have a
>ground through the firewall, and will have a second in the front- which
>could come directly from the battery, and not have to come to the front from
>the rear ground - is this correct? I don't want to have a problem with the
>indications on my instruments...
Do you have a copy of the AeroElectric Connection? If not, at least
download
the update chapters available from my website. This one on grounding at:
http://www.aeroelectric.com/articles/Rev9/ch5-9.pdf
and this on system architecture at:
http://www.aeroelectric.com/articles/Rev10/z10.pdf
and this on system reliablity at:
http://www.aeroelectric.com/articles/Rev9/ch17-9.pdf
If you find these chapters useful, then I'd recommend you
get the whole book at
http://www.aeroelectric.com/Catalog/AECcatalog.html
Bob . . .
Message 26
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| Subject: | AMP / Cannon Connectors |
--> AeroElectric-List message posted by: "David Schaefer" <dschaefer1@kc.rr.com>
Bob .. this may be more of a philosophical question vs. a 'best
electrical practices' question. I've always been taught not to 'break'
a wire if it can be avoided i.e. a solid wire was better than two
pieces.
However, now that I've got miles of wire strung out I'm becoming
enamored with cannon connectors both bulkhead and in-line to make my
life easier and make the airplane more serviceable when I'm on my back
under the panel! When I look at 'production' planes from 747's to
F-16's I see gaggles of cannon-type plugs and they seem to have workable
electronics.
What are the plusses and minuses of using these connectors? Breaking
wires? I've got access to good gold-plated pins etc.
Regards,
David
Message 27
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
At 07:44 PM 10/28/2003 -0500, you wrote:
>--> AeroElectric-List message posted by: "Ernest Kells"
><ernest.kells@sympatico.ca>
>
>Bob, Matt and others:
>
>Let me state my question with a little more info - I basically don't even
>know the question but I think I need to understand this now. I am using
>your Z-2 diagram with the always hot bus.
>
>I have a large Prestolite alternator (installed) that I would like to limit
>for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to keep the
>alternator. It is a tight fit - but it does fit. Note: almost all work -
>engine with all appliances and prop hardware, cowling, wiring, heat shields,
>etc., are finished. Change at this stage is not easy. I have installed the
>Vans 40 amp shunt, wire, busses, etc., based upon an overall 40 amp design.
There is no practical way to de-rate an alternator. If it's
a 70A machine, then there are times when your airplane's electrical
system will demand and get all 70A out of it and then some. So if
it's a 70A machine, wire it up like you're going to use it all
even if you don't intend to. 4AWG b-lead feeder and ANL-60 limiter
is recommended.
>Matt Prather stated "I might not understand your question exactly, but I
>think you are asking whether the shunt can be damaged by running too much
>current through it........."
>
>That's my question! But his beautiful answer just confuses me. All I know
>is that I have a voltage regulator and OVM to limit the voltage. It seems
>like I should have a mechanism to limit the amperage output from 70 to no
>more that 40 amps. The only "mechanism" I have in the electron stream is a
>40 amp shunt (a piece of Bakelite with a flat bar). Do I just need a simple
>35 or 40 fuse/circuit breaker on the main bus (#8 wire from battery
>contactor) ???
None of those devices have any control over the alternator's output.
Generators will willingly deliver more than their rated current (burns
brushes, throws solder off the commutator) so generator output was indeed
limted by features built into the regulator (See Chapter 4 in the
'Connection).
Alternators are inherently current limited by their magnetic design
(See chapter 3 of the 'Connection) so there is no need for an
alternator regulator to sense alternator load current . . . much
less do anything about it. The 40A shunt will be just fine . . .
but there will be short periods of time after engine starting
that the loadmeter will be "pegged" until the battery charges
up. This is not a big deal.
Bob . . .
Message 28
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| Subject: | Fwd: Reply from Nova RE: Installation Diagrams |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
Just got this response from Nova as to their recommendations
for shield ground treatment. Steve didn't mention why it wasn't
covered in the installation manual but his recommendations were
consistent with my own . . .
Bob . . .
>Subject: RE: Strobe System Installation Diagrams
>Date: Tue, 28 Oct 2003 18:54:51 -0500
>X-MS-Has-Attach:
>X-MS-TNEF-Correlator:
>Thread-Topic: Strobe System Installation Diagrams
>Thread-Index: AcOdluDGjX/2Lyz4QsiUJHK/bHwxPgAF7Pqg
>From: "Stephen Hanley" <sghanley@strobe.com>
>To: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>Cc: "Kimberly Fritsch" <kfritsch@strobe.com>,
> "Eugene Abel" <eabel@strobe.com>,
> "Sandy Havens" <shavens@strobe.com>
>
>Dear Bob:
>
>Thanks for the email. The shields are normally used in environments
>where radio frequency interference is a problem. If you choose to use
>the shields, ground them at the power supply only - to chassis ground.
>Leave the opposite ends disconnected - most customers trim them off.
>
>Thank you.
>
>Sincerely,
>
>Steve for Team Nova
>-----Original Message-----
>From: Robert L. Nuckolls, III [mailto:bob.nuckolls@cox.net]
>Sent: Tuesday, October 28, 2003 4:02 PM
>To: Nova
>Subject: Strobe System Installation Diagrams
>
>
>Good day!
>
>A am looking at installation instructions for your
>which I downloaded from:
>
>http://www.strobe.com/pdfs/eps40X-install.pdf
>
>I can find no recommendations for how the shield grounds
>are to be treated in the strobe-head-to-power-supply cables. Can you
>enlighten me?
>
>Thanks!
>
> Bob . . .
Message 29
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| Subject: | Re: Current Limiters |
--> AeroElectric-List message posted by: "Matt Prather" <mprather@spro.net>
Hi Ernest,
Aha... Okay, now I see what you are getting at. I don't think
there is an effective means for 'throttling' an alternator to a
certain current output. The alternator is controlled by a VOLTAGE
regulator. This means that in response to a varying load, the
regulator is going to try to adjust the ammount of current coming
out of the alternator to keep the VOLTAGE within the specified
range (usually about 14V). The bigger the load on the bus, the
larger the initial sag, and the larger response from the regulator.
This will continue until the alternator is max'ed out (around 70A).
In your airplane, the only time I can see you exceeding your power
budget is when you are charging a dead battery.
So, here's what I would do... Ditch the 40A shunt and meter. Get a
75A shunt from somewhere (BandC has them for $25), and a meter that
reads in percent (-100-0-100). The meter will indicate full scale when
it recieves 50mV from whatever shunt you install (75A) in this case.
This way, you have the advantage of being able to use the full rated
output of the boat anchor that you are paying to haul around. That
will be nice when you install heated seats, and a mondo landing light.
Plus, the bigger shunt weighs no more, and is the same price as the
40A. If you run the battery flat, the 70A alternator will charge it
much faster than if you were to successfully regulate the 70A down to
40A.
The cheap way might be to keep the meter that you have, and just replace
the shunt... Then, if the meter says 40A, the circuit is really moving
75A... Kind of lame though. If the meter says 20A, then you have 37.5A.
The really cheap way is don't do anything, but just run it, it may
eventually break the mechanism in the meter from knocking the needle
against the stop... I bet you would get away with it for a while though.
How often will the alternator need to put out more than 40A?? Only if
something bad happens.
A shunt isn't designed as a current limiter or regulator in any
way. Its only purpose is to provide a means for MEASURING current
through a section of a circuit. It is instrumentation, only. Ideal
instruments shouldn't effect the behavior of the system being measured.
The ideal shunt/ammeter would cause 0 voltage drop in the circuit, but
50mV is acceptable,
Current limiters are designed to only work when there is some kind of
malfunction on the bus. I don't believe they would be good to use as
another form of regulation.
How's that?
Regards,
Matt-
N34RD
> --> AeroElectric-List message posted by: "Ernest Kells"
> <ernest.kells@sympatico.ca>
>
> Bob, Matt and others:
>
> Let me state my question with a little more info - I basically don't
> even know the question but I think I need to understand this now. I am
> using your Z-2 diagram with the always hot bus.
>
> I have a large Prestolite alternator (installed) that I would like to
> limit for a VFR-only RV-9A. It is an ALX series at 70 amps. I want to
> keep the alternator. It is a tight fit - but it does fit. Note: almost
> all work - engine with all appliances and prop hardware, cowling,
> wiring, heat shields, etc., are finished. Change at this stage is not
> easy. I have installed the Vans 40 amp shunt, wire, busses, etc., based
> upon an overall 40 amp design.
>
snip
> It seems like I should have a mechanism to limit the amperage output
> from 70 to no more that 40 amps. The only "mechanism" I have in the
> electron stream is a 40 amp shunt (a piece of Bakelite with a flat bar).
> Do I just need a simple 35 or 40 fuse/circuit breaker on the main bus
> (#8 wire from battery contactor) ???
>
> Thanks for any help in knocking down this mental block.
>
> Ernest Kells - RV-9A O235-N2C, Wood Prop
> 90 plus % Complete - electrical
>
Message 30
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| Subject: | Re: Aircraft Configuration Spreadsheet |
--> AeroElectric-List message posted by: "George" <gtb@georgesmail.com>
Pete Waters;
You might try to get a copy of the older (free) version
of the (now Microsoft owned) VISIO program. This
usually came with a great many symbols that could be
used to illustrate nearly any kind/type of diagram or
chart that a person could imagine.
Of course, text and descriptions of each item, as well
as layers, or levels within the project are easily done
too. About the easiest, and best, "inexpensive" prog
that I've ever seen, for its' capabilities.
George
P.S.: Of course since MS realized the value of this
program, they have purchased the rights to it,
and added the appropriate value for it to the
consumer's required input for usage.
---
Message 31
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| Subject: | Re: Run away alternator scenario |
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <bob.nuckolls@cox.net>
>
>...................SKIP...............We've got an external voltage regulator
>powered via a 5 amp field supply breaker. However, virtually all light
>aircraft then power the field breaker from the battery side of the 'B' lead
>fuse/breaker (typically 40 to 60 amps rating).
>If this main breaker/fuse opens, the VR senses low voltage and maximizes
>alternator field current in the impossible attempt to restore 13.8 to 14.5
>volts on
>the disconnected buss. The result is 100+ volts at the alternator B terminal
>and sometimes severe alternator damage involving the faults mentioned. In my
>opinion, the field supply breaker should be powered from the alternator side
>of the main breaker. Regards, Mike>>
This has circulated around the lists for years. The scenario
is true IF you open the b-lead breaker without also shutting
off the field . . . and this can be REALLY important for the
majority of certified airplanes where the b-lead breaker is
designed to nuisance trip (see chapter 17 of the 'Connection).
Modern OBAM aircraft designs provide sufficient headroom in b-lead
protection to prevent the dreaded condition cited. So, the only
time we expect b-lead protection to open is when shorted diodes
or some other serious malady has befallen the alternator in which
case, the thing needs to be worked on anyhow. The design goal is
to protect the AIRPLANE from the alternator, not protect the
alternator from itself. By eliminating the probability of nuisance
tripping the b-lead protection, concerns cited in this anecdote
are alleviated.
Bob . . .
Message 32
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| Subject: | Re: Fwd: Reply from Nova RE: Installation Diagrams |
--> AeroElectric-List message posted by: Joa Harrison <flyasuperseven@yahoo.com>
Thanks a bunch Bob. Good to get confirmation.
Can I have you look at one more thing?
http://www.aeroflash.com/156-0049.pdf
Why do I have to run a ground wire to the black wire when the nav and strobe lamps
are internally grounded to the case? Can I just ground the black wire to
the case or should I run a ground wire all the way from the grounding block on
the firewall? Or perhaps run a ground wire from the strobe supply (that is also
connected to the supply mount and the drain wire)?
In the Aeroflash FAQ ( http://www.aeroflash.com/faq.html ) it says to use shielded wire to run to the power supply. Is this necessary and/or beneficial?
BTW I *finally* finished all my Microair radio wiring tonight including using the
two relays exactly per your diagram. Works like a charm and I'm very pleased!
Thanks for the help!
Joa
++++++++++++++++++++++++++++++++++++++++
heir recommendations
for shield ground treatment. Steve didn't mention why it wasn't
covered in the installation manual but his recommendations were
consistent with my own . . .
---------------------------------
Exclusive Video Premiere - Britney Spears
Message 33
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--> AeroElectric-List message posted by: "Kingsley Hurst" <khurst@taroom.qld.gov.au>
Bob,
I recently purchased your "AeroElectric Connection" book and firstly
wish to congratulate and thank you for producing this excellent
publication for "first timers" like myself. It has been invaluable.
I am going to adopt most if not all of your ideas including fast-on
connectors and blade fuses etc.
Whilst I have no violent objection to having the fuse holders behind the
panel, I would prefer access to them from in front of the panel simply
to make life easier if one suspects a blown fuse. I have no desire to
carry out inflight diagnostics and repairs.
To this end, I have come across the 15710 Series Rear Terminal ATC Fuse
Block by Bussmann Auto which I feel would be ideal for my purpose. It's
properties including modular construction, dual buss option, rear access
etc can be seen at http://www.bussauto.com/pdf/rta.pdf
My question is, do you have any intention to stock these fuse blocks or
alternatively, can you advise where I may purchase one or more of them
given that I cannot find a distributor in Australia?
Any assistance you or others may be able to offer would be much
appreciated.
Regards
Kingsley Hurst
Europa Builder in Oz
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