Today's Message Index:
----------------------
1. 01:22 PM - turn coordinator causing noice in headset (jerrytex)
2. 02:33 PM - Current Limiter Question... (idleup)
3. 08:13 PM - Re: Current Limiter Question... (Robert L. Nuckolls, III)
4. 08:21 PM - Re: turn coordinator causing noice in headset (Robert L. Nuckolls, III)
Message 1
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| Subject: | turn coordinator causing noice in headset |
I have had a good deal of electrical issues from strobe noise, to bad crimps that
burned up wires. I have slowly but surely resolved alot of the issues. Recently
I installed an LED landing light. During the course I found other wiring
issues that have been resolved too. However I have strange problem now. I can
hear my Falcon Electronic turn coordinator in my headset. It is whining very noticeably.
What is weird is if I turn ON the landing light, the noise goes away.
Turn the light off and the noise comes back. I worked on this for hours trying
various things with no luck. Here are some things I tried and the results.
1. re-did all the grounds on everything. No change.
2. disconnected turn coordinator. Noise gone with or without the landing light
on.
3. disconnect comm antenna at radio pigtail. Noise is gone.
4. hooked up rubber ducky antenna totally isolated from plane and the noise comes
back.
5. hooked up turn coordinator directly to the battery (this fixed the strobe noise
problem) totally isolating it from the bus power supply. Noise is the same.
In every instance though, I can turn on the landing light and the noise goes away.
I don't get it?
It seems like it is coming in through the antenna but why would turning the landing
light on make it go away. Anyone have any ideas? Filter maybe?
Plane is a Kitfox with 912 ul.
Icom radio IC A-200
Flightcom intercom
DM antenna
Lightspeed QFR headset
Read this topic online here:
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Message 2
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| Subject: | Current Limiter Question... |
I am a bit confused and thought I would ask here for clarification. I am trying
to design my electrical system from Z-13/8. It looks as though there is a direct
route for the power direct to the battery and if the wire from the master
relay to the power buss shorts out the full current of the battery would flow
with no circuit protection? should their be a current limiter between there?
Also, it is not specified on the drawing, is this a 4AWG wire between the battery
contactor and the main power bus?
Thanks,
Matt
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=385816#385816
Message 3
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| Subject: | Re: Current Limiter Question... |
At 04:32 PM 10/22/2012, you wrote:
>
>I am a bit confused and thought I would ask here for clarification.
>I am trying to design my electrical system from Z-13/8. It looks as
>though there is a direct route for the power direct to the battery
>and if the wire from the master relay to the power buss shorts out
>the full current of the battery would flow with no circuit
>protection? should their be a current limiter between there?
No. Those are "fat wire" feeders that have never benefited
from circuit protection in light aircraft.
This philosophy is an echo of design goals for light aircraft
as described in FAR23:
Sec. 23.1357 Circuit protective devices.
(a) Protective devices, such as fuses or circuit breakers, must be
installed in all electrical circuits other than--
(1) Main circuits of starter motors used during
starting only; and
(2) Circuits in which no hazard is presented by
their omission.
(b) A protective device for a circuit essential to flight
safety may not be
used to protect any other circuit.
(c) Each resettable circuit protective device ("trip free"
device in which
the tripping mechanism cannot be overridden by the operating
control) must be
designed so that--
(1) A manual operation is required to restore
service after tripping; and
(2) If an overload or circuit fault exists, the
device will open the
circuit regardless of the position of the operating control.
(d) If the ability to reset a circuit breaker or replace a fuse is
essential to safety in flight, that circuit breaker or fuse must be so
located and identified that it can be readily reset or
replaced in flight.
(e) For fuses identified as replaceable in flight--
(1) There must be one spare of each rating or 50
percent spare fuses of
each rating, whichever is greater; and
(2) The spare fuse(s) must be readily accessible to
any required pilot.
>Also, it is not specified on the drawing, is this a 4AWG wire
>between the battery contactor and the main power bus?
How much current is going to flow in it? The z-figures
are ARCHITECTURE drawings, not wiring diagrams. The wire
sizes are selected in accordance with anticipated loads.
4AWG is certainly large enough and wouldn't hurt but it
could be smaller as dictated by a load analysis.
Bob . . .
Message 4
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| Subject: | Re: turn coordinator causing noice in headset |
At 03:21 PM 10/22/2012, you wrote:
>
>I have had a good deal of electrical issues from strobe noise, to
>bad crimps that burned up wires. I have slowly but surely resolved
>alot of the issues. Recently I installed an LED landing light.
>During the course I found other wiring issues that have been
>resolved too. However I have strange problem now. I can hear my
>Falcon Electronic turn coordinator in my headset. It is whining very
>noticeably. What is weird is if I turn ON the landing light, the
>noise goes away. Turn the light off and the noise comes back. I
>worked on this for hours trying various things with no luck. Here
>are some things I tried and the results.
>
>1. re-did all the grounds on everything. No change.
>2. disconnected turn coordinator. Noise gone with or without the
>landing light on.
>3. disconnect comm antenna at radio pigtail. Noise is gone.
>4. hooked up rubber ducky antenna totally isolated from plane and
>the noise comes back.
>5. hooked up turn coordinator directly to the battery (this fixed
>the strobe noise problem) totally isolating it from the bus power
>supply. Noise is the same.
Your experimental results suggest radiated noise . . .
probably through wiring. These filters are on sale
right now
http://tinyurl.com/8aszmkb
Put an order in at http://tinyurl.com/36e7ddd
I'll mail you one. If it fixes it, I'll bill you
the $10 + postage. If not, we gotta go to plan B.
>In every instance though, I can turn on the landing light and the
>noise goes away. I don't get it?
Those T/C are noteworthy for their noise
generation. You could first try installing a 0.1
uF, capacitor (Radio Shack 272-1053) across
the incoming power pins at the back of the
instrument.
Bob . . .
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