Today's Message Index:
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1. 08:02 AM - User name (speedy11@aol.com)
2. 09:15 AM - Re: User name (donjohnston)
3. 09:18 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
4. 10:26 AM - Audio Noise (user9253)
5. 10:41 AM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
6. 11:22 AM - Re: User name (Robert L. Nuckolls, III)
7. 11:23 AM - Re: Alternator problem? (donjohnston)
8. 12:53 PM - Re: Re: Alternator problem? (Robert L. Nuckolls, III)
9. 01:35 PM - Re: Alternator problem? (user9253)
10. 02:04 PM - Re: Audio Noise (Charlie England)
11. 02:30 PM - Re: Re: Alternator problem? (Charlie England)
12. 04:38 PM - Z-11 Diagram and E-bus feeder length (Garyw)
13. 05:39 PM - Re: Z-11 Diagram and E-bus feeder length (Robert L. Nuckolls, III)
14. 05:45 PM - Re: Audio Noise (Robert L. Nuckolls, III)
15. 07:43 PM - Re: Alternator problem? (user9253)
16. 08:04 PM - Re: Re: Alternator problem? (Charlie England)
Message 1
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Matt,
I can't remember my username to log on to the list. Without the user name I am
not allowed to request a new password.
So, how can I get my user name?
Do not archive
Stan Sutterfield
Message 2
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If you're posting a message... doesn't that mean you're logged in?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444122#444122
Message 3
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| Subject: | Re: Alternator problem? |
>
>You just went over my head with "brush-bounce". :(
The term "bounce" is probably inappropriate . . .
"discontinuity" is probably a better description.
Brush bounce is a real phenomenon usually promoted
by out-of-round slip rings or gross contamination
of the surface.
An artfully crafted slip ring receives final
finish with the armature shaft captured between
centers and cut with a diamond tipped tool with
cutting depth and rates so tiny that the finish
is mirror smooth.
Now, press a chunk of carbon to that surface while
it romps along at 200 inches per second . . . and
that 'smoothness' can take on a new character
as tiny bits of material transfers from the brush
to the slip-ring. Over time measured in hours,
a 'film' is formed on the copper. The charcater and
rate of deposition is a function of current magnitude
and direction in the brush, moisture, brush material makeup,
pressure, and probably a few other things the sub-microscopic/
molecular level. See: http://tinyurl.com/q9q62eb
It ALWAYS happens and is built into the nature of
machines with brushes. Problems can manifest when
some feature of associated electronics is
sensitive to the discontinuity. The 30 year arm
wrestling match with the TC regulator has roots
in just such a sensitivity
>I'm all for grins! Can you give me an idea where to get or how to
>build this filter?
What is the center-to-center distance for
the F1 to F2 terminals on your alternator?
I crafted a filter to conduct some experiments
on the problem aircraft that seemed to 'fix' the
problem . . . more appropriately 'mask' the
problem. It didn't fix the design descrepancy
in the regulator . . . only broke the propagation
mode between the antagonist (perfectly normal
brush behavior) and the victim (an uber-sensitive
OV sense mechanism).
As a quick, interim experiment, try connecdting a high
quality, 1 uF capacitor from F1 to F2 on your alternator.
NOT an electrolytic but a some form of metal-film device.
I've got a few hundred laying around . . . can send
you one of those right away.
Bob . . .
Message 4
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Below is a quote from a RV-12 builder in Australia, as posted on VansAirforce:
> I've had a constant `bzzt....bzzt...bzzt' sound in my headset repeated at exactly
one second intervals. Both pilot and co-pilot sides were affected. The sound
level stayed constant despite adjusting the intercom squelch and volume knobs,
and was unaffected by the transponder, radio, autopilot or lights. At first
I thought the sounds were related to the flashing warning signs on the Dynon,
but later realised they were exactly timed to the digital clock on the display.
The noise would start as soon as the boot sequence got to `starting network
manager'. If I unplugged the GPS antenna from the AV5000 module so that the
system couldn't pick up the time signal from the satellites, the clock would
not appear and neither would the noise. Dynon initially thought it might be related
to the transponder, but neither disconnecting the transponder, the EMS,
or anything else seemed to make any difference. If the clock was active, so was
the noise. The only way to get rid of it was to disconnect the GPS antenna,
which wasn't really a good solution. However, flying with the noise wasn't an
option either as it was as irritating as a dripping tap.
> However, I got lucky this afternoon when a local electronics guru happened to
be at the field. He spent a couple of hours trouble-shooting the system, checking
the Skyview settings, the radio, tracing the wiring diagram, pulling pins,
etc, until he eventually discovered that the noise was apparently being generated
by interference between the music jack wires and the tunnel harness, which
runs to the ADAHRS mounted in the tail cone. When the GPS antenna was connected,
it appears that EMF generated in the network cable was being fed into the
audio wires that run close to the cable in the tunnel, and was therefore audible
in the headsets. Disconnecting the two audio wires fixed the problem. It
was a simple solution, but tracking down the cause has been a very frustrating
exercise. Glad it's been fixed now.
The length of the shared wire harness is five feet. We will never know the true
cause. But is it more likely that the audio interference was due to the proximity
of wires, or due to the fact that the stereo music input jack was grounded
locally to the airframe (without isolating washers) instead of having a dedicated
ground wire running back to the instrument panel ground?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444125#444125
Message 5
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| Subject: | Re: Alternator problem? |
At 06:40 PM 6/27/2015, you wrote:
Directions for making a filter:
http://www.sanantoniohams.org/tips/whine.htm
> You just went over my head with "brush-bounce".
Alternators have bushes that ride on slip rings. If the rings are
not concentric, the brushes will move up and down in their holders.
. . . and under some conditions, experience
periodic disconnections from the slip ring . . .
Which is probably not the phenomenon were
working with here . . . as described in my
recent post, the discontinuity of interest
may have more to with quality of brush-track
than from mechanical imperfections in surface
or concentricity . . . but in any case SHOULD
NOT be a component of root cause for OV trips
in a well design OV sense system.
By the way, it's been a persistent notion in some
circles for decades that 'automotive' hardware
with brushes are ill-suited to use on aircraft due
to effects of altitude leading to mis-interpreted
assumptions that atmospheric pressure has a profound
effect on brush performance. As pointed out in the
the article I cited earlier, MOISTURE is a high-influence
predictor of brush performance . . . and failure to
perform at altitude has a lot to do with humidity
and nearly nothing to do with altitude.
"Altitude rated" brushes are really "low humidity
rated" devices with chemistry added to the brush-makeup
that compensates for reduced atmospheric moisture at
altitude. But even those effects are much more pronounced
on high current density brushes that ride on commutators
as opposed to 3A max, 1A normal loads on alternator
slip-rings. The collective experience of both TC
and OBAM aviation communities have demonstrated that
altitude effects are VERY low on the totem-pole
of stresses that raise risk.
> can you give me some idea of where I may have a disconnection in
the "discontinuity in assembly of simple-ideas that govern performance
I get the impression that Bob is inferring that he does not trust the VP-X.
Didn't say that. What I'm saying is that I do
not have enough information about the VP-X OV
protection philosophy to discount the possibility
that NORMAL alternator-noises are participating in nuisance
trips.
I suggest that instead of pulling the alternator, that you replace
the voltage regulator with a generic Ford VR166 or equivalent. There
is a list in Bob's book. The over-voltage and low voltage features
of the LR3 are not needed in your application if the VP-X provides
over-voltage and the EFIS gives low voltage warning.
An excellent experiment. If the VR-166 style
regulators are presently fitted with OV protection,
it's performance benchmarks are certainly going
to be different than an LR3. If the nuisance
trips go away with THAT regulator, then there
is reason to investigate the LR-3 more closely.
If they continue, then the difficulty will be
have root cause in features found elsewhere.
Bob . . .
Message 6
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At 10:00 AM 6/28/2015, you wrote:
>Matt,
>
>I can't remember my username to log on to the list. Without the
>user name I am not allowed to request a new password.
>So, how can I get my user name?
>
>Do not archive
>
>Stan Sutterfield
Hi Stan, I searched thorough the archives looking
for an instance where you accessed the Lists
via browser as opposed to the email List-server.
One of those posting would be tagged with your username.
You apparently didn't use the browser-portal very
often . . . but you're probably in there. I've
included a direct message to Matt so see if
he can help.
Bob . . .
Message 7
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| Subject: | Re: Alternator problem? |
> I suggest that instead of pulling the alternator, that you replace the voltage
regulator with a generic Ford VR166 or equivalent. There is a list in Bob's
book. The over-voltage and low voltage features of the LR3 are not needed in your
application if the VP-X provides over-voltage and the EFIS gives low voltage
warning.
>
> An excellent experiment. If the VR-166 style
> regulators are presently fitted with OV protection,
> it's performance benchmarks are certainly going
> to be different than an LR3. If the nuisance
> trips go away with THAT regulator, then there
> is reason to investigate the LR-3 more closely.
> If they continue, then the difficulty will be
> have root cause in features found elsewhere.
I thought that voltage regulators were voltage specific? Are these generic VR's
available in 28v versions?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444130#444130
Message 8
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| Subject: | Re: Alternator problem? |
>I thought that voltage regulators were voltage specific? Are these
>generic VR's available in 28v versions?
OOPS! You caught us with our perceptions down . . .
yes, the VR166 is 14v only. Scratch that idea.
Bob . . .
Message 9
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| Subject: | Re: Alternator problem? |
> I thought that voltage regulators were voltage specific? Are these generic VR's
available in 28v versions?
Oops, my mistake. I forgot about the 28 volt system. I do not know of any generic
28 volt regulators.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444134#444134
Message 10
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On 6/28/2015 12:24 PM, user9253 wrote:
>
> Below is a quote from a RV-12 builder in Australia, as posted on VansAirforce:
>
>> I've had a constant `bzzt....bzzt...bzzt' sound in my headset repeated at exactly
one second intervals. Both pilot and co-pilot sides were affected. The sound
level stayed constant despite adjusting the intercom squelch and volume knobs,
and was unaffected by the transponder, radio, autopilot or lights. At first
I thought the sounds were related to the flashing warning signs on the Dynon,
but later realised they were exactly timed to the digital clock on the display.
The noise would start as soon as the boot sequence got to `starting network
manager'. If I unplugged the GPS antenna from the AV5000 module so that the
system couldn't pick up the time signal from the satellites, the clock would
not appear and neither would the noise. Dynon initially thought it might be related
to the transponder, but neither disconnecting the transponder, the EMS,
or anything else seemed to make any difference. If the clock was active, so was
the noise. The only way to get rid of it was to di!
> sconnect the GPS antenna, which wasn't really a good solution. However, flying
with the noise wasn't an option either as it was as irritating as a dripping
tap.
>> However, I got lucky this afternoon when a local electronics guru happened
to be at the field. He spent a couple of hours trouble-shooting the system, checking
the Skyview settings, the radio, tracing the wiring diagram, pulling pins,
etc, until he eventually discovered that the noise was apparently being generated
by interference between the music jack wires and the tunnel harness,
which runs to the ADAHRS mounted in the tail cone. When the GPS antenna was connected,
it appears that EMF generated in the network cable was being fed into
the audio wires that run close to the cable in the tunnel, and was therefore
audible in the headsets. Disconnecting the two audio wires fixed the problem.
It was a simple solution, but tracking down the cause has been a very frustrating
exercise. Glad it's been fixed now.
> The length of the shared wire harness is five feet. We will never know the
true cause. But is it more likely that the audio interference was due to the
proximity of wires, or due to the fact that the stereo music input jack was grounded
locally to the airframe (without isolating washers) instead of having
a dedicated ground wire running back to the instrument panel ground?
> Joe
>
> --------
> Joe Gores
For noise problems, I always look at ground issues first. In my opinion,
he needs to fix the ground issue whether that particular problem was
caused by it or not. And if that jack was grounded, then there may be
others that have similar issues.....
Charlie
Message 11
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| Subject: | Re: Alternator problem? |
On 6/28/2015 3:34 PM, user9253 wrote:
>
>
>> I thought that voltage regulators were voltage specific? Are these generic VR's
available in 28v versions?
> Oops, my mistake. I forgot about the 28 volt system. I do not know of any generic
28 volt regulators.
>
> --------
> Joe Gores
They are out there; just not so easy to find. 1st hit I got:
http://www.ebay.com/itm/NEW-24-VOLT-POSITIVE-OR-NEGITIVE-GROUND-REGULATOR-D2152-FARM-INDUSTRIAL-/151618159386
Message 12
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| Subject: | Z-11 Diagram and E-bus feeder length |
Z-11 has a note of 6" max write length to the diode and again to the E-bus. Is
this purely a function of the particular write size sunken (16 ga) or is there
and underlying reason to keep this run short?
Tia,
Gary
--------
Gary
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444142#444142
Message 13
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| Subject: | Re: Z-11 Diagram and E-bus feeder length |
At 06:37 PM 6/28/2015, you wrote:
>
>Z-11 has a note of 6" max write length to the diode and again to the
>E-bus. Is this purely a function of the particular write size sunken
>(16 ga) or is there and underlying reason to keep this run short?
This is a legacy hand-me-down rule-of-thumb
that goes back a few years . . . at least 50
that I know about.
The GENERAL RULE for protection of wires is
defined in AC43-12 and the FARS. But . . .
suppose you wanted to feed some device in
very close proximity to the high current
feeder. The rule of thumb (which I don't
recall having ever been articulated in
regulation) was any wire of 6" or less that
can be 'burned' without putting the airframe
and passengers at risk, does not need to
be protected (meaning fuse, circuit breaker,
fusible link, etc.).
The first time I recall this r-o-t being exercised
was in the wiring of a fat electrolytic capacitor
to the bus (ostensibly for spike/noise/gremlim
protection) and later for the wiring of a 50W zener
to the bus for the same purpose.
In retrospect, I am amazed at the thrashing and
agonizing brought on by worries about spikes, noises
and things that go "bump in the night" when in fact,
DO-160/MIL-STD-704 suggestions applied with understanding
made all those concerns evaporate.
So you will find SOME wires on my drawings marked
with an (*) wherein no protection is shown upstream
of the potential fault path for burning the wire.
In some places I use the symbol (*) to suggest that
the devices so connected should be in close proximity
to each other. So the rationale behind the symbol
may not be immediately obvious . . . but there is
one.
Bob . . .
Message 14
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>For noise problems, I always look at ground issues first. In my
>opinion, he needs to fix the ground issue whether that particular
>problem was caused by it or not. And if that jack was grounded, then
>there may be others that have similar issues.....
>
>Charlie
Yes . . . this is excellent advice on airframes
where no particular philosophy for grounding
has been adopted BEFORE wires were strung.
Over the years, places like Beech, Cessna, et. als.
developed design and process specs for the construction
of new systems in their products. Noise issues were
rare because lessons learned (some of them painful and
expensive) were core knowledge for development
of those specs.
To be sure, the first question to be explored on
discovery of any noise problem in an OBAM aircraft
is, "What does your ground system architecture look
like?"
Bob . . .
Message 15
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| Subject: | Re: Alternator problem? |
24 volt Voltage regulator, eBay item number:151689173831, is only $10. Has anyone
ever tried to adapt an internal voltage regulator for external use?
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=444149#444149
Message 16
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| Subject: | Re: Alternator problem? |
On 6/28/2015 9:42 PM, user9253 wrote:
>
> 24 volt Voltage regulator, eBay item number:151689173831, is only $10. Has anyone
ever tried to adapt an internal voltage regulator for external use?
> Joe
>
> --------
> Joe Gores
I wondered about that, as well. Shouldn't be too big a deal for someone
handy with a soldering iron.
Charlie
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