Today's Message Index:
----------------------
1. 04:44 AM - Daisy-Chaining Stereo Inputs (Mark Chamberlain)
2. 09:39 AM - Re: Daisy-Chaining Stereo Inputs (Robert L. Nuckolls, III)
3. 10:49 AM - Re: Some experiments fail (Robert L. Nuckolls, III)
4. 11:10 AM - Oops! (Robert L. Nuckolls, III)
5. 11:39 AM - Over Voltage (Sally Kilishek)
6. 12:00 PM - Re: Some experiments fail (Robert L. Nuckolls, III)
7. 12:01 PM - Re: Daisy-Chaining Stereo Inputs (Robert L. Nuckolls, III)
8. 12:05 PM - Re: Oops! (Mickey Coggins)
9. 01:14 PM - Back-Up Battery ground (Carlos Trigo)
10. 01:38 PM - Re: Re: Daisy-Chaining Stereo Inputs ()
11. 01:55 PM - Re: Oops! (Chuck Jensen)
12. 08:21 PM - Headphone Out connection to Aircraft Mic input (Scott Winn)
Message 1
INDEX | Back to Main INDEX |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Daisy-Chaining Stereo Inputs |
Hi All and Happy Christmas!
I am trying to get stereo input from multiple sources (MP3, GPS, Traffic
etc.) in to my FlightCom 403 intercom. I figured it might work by just
"daisy-chaining" them together but if I have more than one plugged it at
once I get some sort of nasty feedback. Is there some sort of device I
need in between them so they can't "see" each other?
Thanks for your help,
Mark - N234C
Flying - 48 hours
Message 2
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Daisy-Chaining Stereo Inputs |
At 05:41 AM 12/24/2006 -0700, you wrote:
>Hi All and Happy Christmas!
>
>I am trying to get stereo input from multiple sources (MP3, GPS, Traffic
>etc.) in to my FlightCom 403 intercom. I figured it might work by just
>"daisy-chaining" them together but if I have more than one plugged it at
>once I get some sort of nasty feedback. Is there some sort of device I
>need in between them so they can't "see" each other?
>
>Thanks for your help,
The problem is not so much one of "feedback" as it is
for "loading". Each source, while not supplying energy
to the signal stream presents a potential for being a load.
this means that while one source is being used, it sees multiple
loads that may affect both signal intensity and frequency
response. MUCH better that you use an isolation (mixing) amplifier
if you want to use multiple sources simultaneously or a simple
two-pole, three-position switch (like miniature 4-pole, on-on-on
switch) for selecting each source one at a time.
However, you won't damage anything with the daisy chaining
experiment. Give it a try. It might prove satisfactory to your
needs . . . it's just not the best we know how to do.
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 3
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Some experiments fail |
At 09:28 PM 12/23/2006 -0400, you wrote:
>
>Harold,
>
>1. I think that is actually a water drain hole.
>
>2. If someone did the engineering and flight testing required to use
>a static source on a pitot tube, it would be specific to one exact
>mounting location and mounting angle on only one type of aircraft.
>It wouldn't be practical for Dynon to do the flight testing required
>to define a mounting location for each type of aircraft that people
>would want to mount this pitot on. Each aircraft type would probably
>require at least a dozen hours of flight testing, with mod work
>required to move the pitot tube around every two or three flights.
>Huge job.
There are a number of probes that offer both static and pitot
pressure sensing. Obviously, the dynamic portion has an opening
on the end and the static portion is generally ported to the
external environment through a ring of holes just behind the
nose opening. Pitot-Static probes, as you already know, have two
fluid fittings instead of one. They are much more difficult to
build under the current ice-survival rules. See complex
maze of passages JUST to handle ice crystals and ingested
moisture for a pitot-only tube at:
http://www.aeroelectric.com/Pictures/Pitot_Tube/Pitot_Tube_Heater.jpg
It may now be impossible if not simply impractical to combine
both functions into a single device. But for non-aviation, precision
airflow measurements, combined pitot-static probes are quite
common. See:
http://www.unitedsensorcorp.com/pitot_frame.html
http://www.flowkinetics.com/measurement.htm
If I can put my hands on one of the older pitot-static probes
I've had laying around here, I'll post some photos.
But Kevin is right-on with his observations of the difficulty
for achieving acceptable pitot-static measurements in a
consumer environment (read repeatable from airplane to airplane
and known, stable boundaries on accuracy). You wouldn't believe
the hoops we've jumped through to meet the new RVSM (reduced
vertical separation minimums) that have effectively doubled the
number of over-water airways by stacking airplanes in at twice
the old vertical density.
Now, one of the really hot items on the pilot's pre-flight
inspection is to spit-polish the areas around the pitot static
system ports to make sure that no contamination has altered the
aircraft's ability to detect and hold an assigned altitude.
Even after all the fussing is over and the type-certificate is
awarded, few if any systems are perfect. This give rise to the
Calibrated Airspeed and Calibrated Altitude differential charts
found in many pilot's operating handbooks.
Good pitot static measurements become exponentially difficult
as your need for accuracy drops below 2 or 3 percent. The pitot
static systems installed on our flight test aircraft are big, heavy,
and would look really ugly installed on your RV.
The J-3 stuck a piece of copper tube out in the breeze ahead of
and below the wing. The performance was adequate for that class
of airplane and the way it was used. I used to show my renters how
to comfortably operate that airplane with the panel completely
covered. But as we move up in performance and our demands on
knowing the real numbers go up, it can be difficult and expensive
to get them all right under all conditions.
Bob . . .
Message 4
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
. . . and you thought failure to drop the wheels on your
Bonanza was expensive! See:
http://www.zianet.com/tedmorris/dg/bombers4.html
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 5
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
I'm using a generic Ford regulator (Wells VR749) and a
B&C OVM-14 overvoltage module wired as per Z-22 in my
RV8.
It worked fine for a short time, but after about 4
hours of flying, the overvoltage indicator light
started flickering. Bus voltage is rising above 15
volts (one time as high as 16 volts), then dropping
back below 15 volts and immediately rising again.
It looks to me like the regulator isn't regulating and
that the OV module is cutting off the field excitation
until voltage drops below 15.
I've replaced the regulator twice, but the problem
continues.
Is there somewhere else I should be looking?
George
N57GK
__________________________________________________
Message 6
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Some experiments fail |
At 08:07 PM 12/23/2006 -0500, you wrote:
>After 4 hours of fiddling, I was able to drop the SWR to 7.3 by moving the
>point where it attaches to the tube. I actually was able to get it to
>drop to 1 at one point. I installed a T connector...the antennae on the
>leg, the line coming off one side of the top and a 50 ohm termination on
>the other side. I don't think that counts though.
Sounds like you're attempting to "gamma-match" the mast of
your pitot tube as a useful radiator.
http://www.vk1od.net/GammaMatch/gamma.htm
For this technique to begin to be successful, the overall
length of the mast must be close to 1/4 wavelength at the
frequency of interest. In the case of comm antennas, let us
assume a center frequency of 126 Mhz. So 300/126 yields
2.4 meters for full-wave or .6 meteres for 1/4-wave.
In the clumsy system currently favored by the intellectually
unwashed, this comes to 23.4 inches. This is the length
of pitot tube you need to start with.
Now, a Google search of "gamma match" on the 'net
will yield a wealth of data on the physics and techniques
of gamma matching. In a nutshell, your goal is to attach
a 50 ohm feedline to some point along the antenna's length
so as to achieve the best match . . . obviously, the antenna's
impedance at the base is damned-small-ohms and up in the
gazillion-ohms range at the top. SOMEWHERE between the base
and the top, we should find the utopian 50 ohm point. Problem
is that any conductor you use to run between end of the coax
and the physical attach point on the antenna has significant
INDUCTANCE at our frequency of interest. This is why all
the articles you'll find on gamma-matching will incorporate
two variables. Physical attach-point on the radiator and
an adjustable capacitance for "series-resonating" the
offending inductance and making it disappear.
You don't describe the details of your experiment but if
you have a better description and perhaps photos to share,
we can help you move this exercise forward. Just know that
the first essential elements are overall length (at least
1/4 wave), feed point location and inductive reactance
elimination by use of variable capacitor.
These features go ONLY to achievement of an acceptable
standing wave ratio. Once the antenna appears to be efficiently
accepting (or delivering) energy, then one can turn to issues
of radiation efficiency. Is the polarization optimized? Is
the radiation pattern acceptably devoid of performance killing
nulls? Is the radiation resistance a significant if not major
portion of the antenna total impedance. I've seen antennas with
1:1 swr having impedances of 50 ohms and radiation resistances
on the order of 1 ohm . . . the thing gets about 2% of applied
energy launched into the ether while the rest is a feeble and
inefficient attempt to de-ice the antenna.
For those of us who are interested in the simple-ideas that
support antenna performance, may I suggest a peek at:
http://www2.arrl.org/tis/info/whyantradiates.html
Antennas are really interesting pieces of technology and it
doesn't take a lot of equipment and even less "black art" to
fabricate useful designs. I would only caution that if the goal
is to achieve a 1/4 to 1/2-knot more speed by reducing antenna
drag on your OBAM aircraft, be aware that the return on investment
for the $time$ expended might be disappointingly small. If the
goal is to understand more about how these critters work, then
your return on investment can be considerably better.
Bob . . .
Message 7
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Daisy-Chaining Stereo Inputs |
>>
>>I am trying to get stereo input from multiple sources (MP3, GPS, Traffic
>>etc.) in to my FlightCom 403 intercom. I figured it might work by just
>>"daisy-chaining" them together but if I have more than one plugged it at
>>once I get some sort of nasty feedback. Is there some sort of device I
>>need in between them so they can't "see" each other?
>>
>>Thanks for your help,
>
> The problem is not so much one of "feedback" as it is
> for "loading". Each source, while not supplying energy
> to the signal stream presents a potential for being a load.
> this means that while one source is being used, it sees multiple
> loads that may affect both signal intensity and frequency
> response. MUCH better that you use an isolation (mixing) amplifier
> if you want to use multiple sources simultaneously or a simple
> two-pole, three-position switch (like miniature 4-pole, on-on-on
> switch) for selecting each source one at a time.
>
> However, you won't damage anything with the daisy chaining
> experiment. Give it a try. It might prove satisfactory to your
> needs . . . it's just not the best we know how to do.
I forgot to add. There's a brief discussion of multiple source
audio mixing in the current update chapter to the 'Connection
which you're free to download at:
http://aeroelectric.com/articles/Rev11/18Audio_R11.pdf
Bob . . .
---------------------------------------------------------
< What is so wonderful about scientific truth...is that >
< the authority which determines whether there can be >
< debate or not does not reside in some fraternity of >
< scientists; nor is it divine. The authority rests >
< with experiment. >
< --Lawrence M. Krauss >
---------------------------------------------------------
Message 8
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
>
> . . . and you thought failure to drop the wheels on your
> Bonanza was expensive! See:
>
> http://www.zianet.com/tedmorris/dg/bombers4.html
>
Ugh. That's a good way to avoid getting promoted.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 9
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Back-Up Battery ground |
Since I will have to put some wheight in the tail of my RV-9A because of W&B
issues, I am planning to install a small battery (probably around 4.5Ah,
depending on its own wheight) to act as a back-up battery for some avionics
(EFIS and Auto-pilot).
For the (+) terminal of that future battery, I already passed a AWG#14
tefzel wire all the way from the tail to the back of instrument pannel, but
for the (-) wire, I am thinking that I could attach it to a ground lug that
I already have in the tail, which is directly connected to the "Main"
battery (-) terminal, and where are also connected the ground wires from the
tail light, the tail strobe beacon and the elevator trim motor.
Can I connect that battery's (-) terminal to the tail ground lug ?
Is there a possibility for ground loop ?
Carlos
Message 10
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Re: Daisy-Chaining Stereo Inputs |
>
> From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
> Date: 2006/12/24 Sun AM 11:37:39 CST
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Daisy-Chaining Stereo Inputs
>
>
> At 05:41 AM 12/24/2006 -0700, you wrote:
>
> >Hi All and Happy Christmas!
> >
> >I am trying to get stereo input from multiple sources (MP3, GPS, Traffic
> >etc.) in to my FlightCom 403 intercom. I figured it might work by just
> >"daisy-chaining" them together but if I have more than one plugged it at
> >once I get some sort of nasty feedback. Is there some sort of device I
> >need in between them so they can't "see" each other?
> >
> >Thanks for your help,
>
> The problem is not so much one of "feedback" as it is
> for "loading". Each source, while not supplying energy
> to the signal stream presents a potential for being a load.
> this means that while one source is being used, it sees multiple
> loads that may affect both signal intensity and frequency
> response. MUCH better that you use an isolation (mixing) amplifier
> if you want to use multiple sources simultaneously or a simple
> two-pole, three-position switch (like miniature 4-pole, on-on-on
> switch) for selecting each source one at a time.
>
> However, you won't damage anything with the daisy chaining
> experiment. Give it a try. It might prove satisfactory to your
> needs . . . it's just not the best we know how to do.
>
> Bob . . .
It might be worthwhile to ask what he means by 'daisychaining'. The most common
meaning in my world is plugging one device into the next, then that device into
the next, etc. If he's doing that, there might easily be 'feedback' issues
depending on how each device handles 'ins' & 'outs'.
Charlie
Message 11
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Voice Recorder...
Landing Checklist Complete? Check. Ohhhhh, myyyyy.
They obviously need one of those squat switches I have on my Velocity
which warns a person when you get slow, and the gear isn't down and
locked. I think I'll put that in their suggestion box....I could even
fax them a wiring diagram!
Chuck Jensen
Do Not Archive
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Mickey Coggins
Sent: Sunday, December 24, 2006 3:05 PM
Subject: Re: AeroElectric-List: Oops!
--> <mick-matronics@rv8.ch>
>
> . . . and you thought failure to drop the wheels on your Bonanza was
> expensive! See:
>
> http://www.zianet.com/tedmorris/dg/bombers4.html
>
Ugh. That's a good way to avoid getting promoted.
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
do not archive
Message 12
INDEX | Back to Main INDEX |
PREVIOUS | Skip to PREVIOUS Message |
NEXT | Skip to NEXT Message |
LIST | Reply to LIST Regarding this Message |
SENDER | Reply to SENDER Regarding this Message |
|
Subject: | Headphone Out connection to Aircraft Mic input |
List,
I have an audio 'alert audio' output that is a headphone out with a
3.5mmaudio jack. My intercom doesn't have an audio input, but I do
have
passenger 3 and passenger 4 mic inputs available since my aircraft is only 2
place.
What kind of a circuit would be needed to connect a headphone out to a
microphone input on an aviation intercom? I know there is power on the
audio line, can it be coupled with an audio transformer to protect the
headphone circuit from the DC power? Would additional components be
necessary? Has anyone made such a circuit before? I want both the pilot
and the co-pilot to hear the alerts, so a Mic input seems like it would work
well if it can be adapted.
--Scott
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|