Today's Message Index:
----------------------
1. 05:34 AM - Fw: Re: Re: Eye Beam Mini LED / RF interference (Buckley William)
2. 06:14 AM - Re: Second big snow in a week! (Bill Bradburry)
3. 06:24 AM - Here is a surprise! (Bill Bradburry)
4. 07:12 AM - Re: Eye Beam Mini LED / RF interference (user9253)
5. 08:37 AM - Re: Here is a surprise! (Werner Schneider)
6. 11:52 AM - Audio Amplifier heads-up (Robert L. Nuckolls, III)
7. 12:50 PM - Audio Amplifier heads-up (Robert L. Nuckolls, III)
8. 01:15 PM - 24x7diy LED noise experiment (update) (Robert L. Nuckolls, III)
9. 01:33 PM - Ground plane diameter (Bill Hibbing)
10. 01:51 PM - Re: Audio Amplifier heads-up (Daniel Hooper)
11. 02:03 PM - Re: Audio Amplifier heads-up (Charlie England)
12. 06:00 PM - Re: Ground plane diameter (Robert L. Nuckolls, III)
13. 06:01 PM - Re: Audio Amplifier heads-up (Robert L. Nuckolls, III)
14. 08:29 PM - Re: Ground plane diameter (William Hibbing)
Message 1
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| Subject: | Re: Eye Beam Mini LED / RF interference |
Sam,
Here's what I came up with for kneeboard lights to do what you're talking a
bout.
William
--- On Sun, 2/24/13, Sam Marlow <sam.marlow@roadrunner.com> wrote:
> From: Sam Marlow <sam.marlow@roadrunner.com>
> Subject: Re: AeroElectric-List: Re: Eye Beam Mini LED / RF interference
> To: aeroelectric-list@matronics.com
> Date: Sunday, February 24, 2013, 3:53 PM
> --> AeroElectric-List message
> posted by: Sam Marlow <sam.marlow@roadrunner.com>
>
> Ok Bob, I have an LED cabin litght that needs a
> on/off/white/red/dimmer switch, any ideas?
>
> Robert L. Nuckolls, III wrote:
> Nuckolls, III" <nuckolls.bob@aeroelectric.com>
> >
> > At 10:07 AM 2/24/2013, you wrote:
> "jonlaury" <jonlaury@impulse.net>
> >>
> >> [/quote]
> >>
> >> Jon, Is this the product you have installed?-
> I'm curious because I was planning on using these
> also.- Thanks.
> >>
> >> http://www.aveoengineering.com/index.php/product-info-eyebeam-mini[/qu
ote]
>
> >>
> >> Bill,
> >> Yes, the same. But I don't know what they mean when
> they say "no external power source required". That would be
> some trick!
> >
> >- Do the offer a 'dumb' version? It's not hard
> >- to build an airplane-friendly knob-operated
> >- on/off/dimmer.
> >
> >
> >---Bob . . .
> >
> >
> >
> >
> >
>
>
===========
> AeroElectric-List Email Forum -
===========
> ---- MATRONICS WEB FORUMS -
===========
> List Contribution Web Site -
> - - - - - - - -Matt
> Dralle, List Admin.
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Message 2
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| Subject: | Second big snow in a week! |
Darn! And pheasant season is over!
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L.
Nuckolls, III
Sent: Monday, February 25, 2013 12:14 AM
Subject: AeroElectric-List: Second big snow in a week!
<nuckolls.bob@aeroelectric.com>
Just got the drive cleared enough to get the
truck out after a 12" snow on Friday, now
they're calling for 16-20" again tomorrow.
The only living thing really happy about all this
is the wheat . . .
They're not expecting freezing rain so maybe
that new generator will still be in the box
next week too. Dr. Dee got home last week before
the snow and has just e-mailed all her students
not to expect her tomorrow . . .
Bob . . .
Message 3
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| Subject: | Here is a surprise! |
http://www.aero-news.net/index.cfm?do=main.textpost
<http://www.aero-news.net/index.cfm?do=main.textpost&id=7929b91b-1927-441c-b
8fd-cca7cb6f595a> &id=7929b91b-1927-441c-b8fd-cca7cb6f595a
Message 4
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| Subject: | Re: Eye Beam Mini LED / RF interference |
Van's Aircraft sells an eyeball light and Light Bracket part number F-12124 .
http://www.vansaircraft.com/cgi-bin/store.cgi?ident=1361800579-166-15&browse=lighting&product=eyeball
Even though the product description says "incandescent", I am pretty sure that
it is LED as used in the RV-12. See this posting:
http://www.vansairforce.com/community/showpost.php?p=397494&postcount=26
Call Van's builder's support to verify before ordering.
The eyeball light in the RV-12 is powered by +12V and negative PWM from the Dynon
dimmer output.
Joe
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=394987#394987
Message 5
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| Subject: | Re: Here is a surprise! |
As usual such infos do need a grain of salt.
The pope was driving a VW for over 75000 km and that car did on ebay got
over 200000$ on a bid after he became pope. So the part not having a
driving licence is very doubtful. I can not comment about his flying
skills however.
Werner
On 25.02.2013 15:23, Bill Bradburry wrote:
> http://www.aero-news.net/index.cfm?do=main.textpost&id=7929b91b-1927-441c-b8fd-cca7cb6f595a
>
> *
>
>
> *
>
Message 6
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| Subject: | Audio Amplifier heads-up |
I've been working with some interesting
audio amplifier modules with very attractive
pricing and performance numbers for the bux.
They're generally described as 5v powered and
will often cite the ability to run off the USB
port of a computer.
http://tinyurl.com/ag3dey2
http://tinyurl.com/bdkt495
http://tinyurl.com/a7gdp3h
These are 'class D' audio amplifiers (switch mode
power supplies that audio rate modulation
response). I've found that they generally perform
as advertised.
I've found that they're sensitive to the output
impedance of the power supply with respect to
internally generated white nose. Further, they're
not two whippy when it comes to rejection of noise
on the 5v line. Noises on a USB supply port
can vary widely from one computer to the next with
lap-tops being the least likely to offer adequately
conditioned power for these devices.
Further, loud passages in program material will drive
the amplifiers into unstable operation that cause
one to grate their teeth. I've found that a LARGE
capacitor (like 10,000 uF) really tames them down
. . . alternatively, an array of ni-mh cells floated
across the power line work just as well . . . and
makes the amplifier portable.
Just a heads up. Class D is one 'wave of the future'
for not-quite hi-fi audio applications. The prices
and performance are attractive . . . but there
are integration issues the user should be aware of.
If you are already, or plan to fiddle with
these critters, I'd be pleased to compare notes
either here on the List or privately.
Bob . . .
Message 7
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| Subject: | Audio Amplifier heads-up |
I've been working with some interesting
audio amplifier modules with attractive
pricing and performance numbers for the bux.
Emacs!
They're generally described as 5v powered and
will often cite the ability to run off the USB
port of a computer.
http://tinyurl.com/ag3dey2
http://tinyurl.com/bdkt495
http://tinyurl.com/a7gdp3h
These are 'class D' audio amplifiers (switch mode
power supplies modulated at audio rates).
I've found that they generally perform as
advertised. Very efficient. I'm presently
listening to some ambient music at pleasant
levels where the two speakers draw an average
of 20 milliamps total at 4v (80 mW power input
to the system).
I've found that they're sensitive to the output
impedance of the power supply with respect to
internally generated white nose. Further, they're
not too whippy when it comes to rejection of noise
on the 5v line. Noises on a USB supply port
can vary widely from one computer to the next with
lap-tops being the least likely to offer adequately
conditioned power for these devices.
Further, loud passages in program material will drive
the amplifiers into unstable operation that gives one
pause for the gnashing of teeth. I've found that a LARGE
capacitor (like 10,000 uF) really tames them down
. . . alternatively, an array of ni-mh cells floated
across the power line work just as well . . . and
makes the amplifier portable.
Just a heads-up. Class D is one 'wave of the future'
for not-quite hi-fi audio applications. The prices
and performance are attractive . . . but there
are integration issues the user should be aware of.
If plan to or already are fiddling with
these critters, I'd be pleased to compare notes
either here on the List or privately.
Bob . . .
Message 8
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| Subject: | 24x7diy LED noise experiment (update) |
The first-pass filter I crafted last week
only offers about 12 dB of attenuation of
noises in the VHF Comm spectrum. I've got
some tubing ordered that will let me
'box up' the filter components and bring
power connection out to a connector.
Working on plan-b.
========= PLAN B ==========
Wasn't able to put my hands on the tubing
I wanted but I ordered an alternative today
which is coming out of Oklahoma. Hope
to get a more effective filter crafted
shortly.
Bob . . .
Message 9
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| Subject: | Ground plane diameter |
I'm upgrading avionics in my Glasair and one of the units I'm adding is a G
armin GDL-88 for ADS-B out. The antenna I'm using is a Comant CI-105 and s
eeing it's a "plastic" airplane I've been wondering if a 6" diameter copper
disc is large enough for the ground plane or should I go a bit larger? TI
A
Bill
Glasair SIIS-FT
-----
No virus found in this message.
Checked by AVG - www.avg.com
Message 10
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| Subject: | Re: Audio Amplifier heads-up |
Have you taken a look at the output RFI? Or is it reasonably well filtered i
n your test PCB? With the highly susceptible nature of some flying widgets, I
'm curious what your take is.
Daniel
On Feb 25, 2013, at 2:46 PM, "Robert L. Nuckolls, III" <nuckolls.bob@aeroele
ctric.com> wrote:
> I've been working with some interesting
> audio amplifier modules with attractive
> pricing and performance numbers for the bux.
>
> <fd7795a.jpg>
>
> They're generally described as 5v powered and
> will often cite the ability to run off the USB
> port of a computer.
>
> http://tinyurl.com/ag3dey2
>
> http://tinyurl.com/bdkt495
>
> http://tinyurl.com/a7gdp3h
>
> These are 'class D' audio amplifiers (switch mode
> power supplies modulated at audio rates).
> I've found that they generally perform as
> advertised. Very efficient. I'm presently
> listening to some ambient music at pleasant
> levels where the two speakers draw an average
> of 20 milliamps total at 4v (80 mW power input
> to the system).
>
> I've found that they're sensitive to the output
> impedance of the power supply with respect to
> internally generated white nose. Further, they're
> not too whippy when it comes to rejection of noise
> on the 5v line. Noises on a USB supply port
> can vary widely from one computer to the next with
> lap-tops being the least likely to offer adequately
> conditioned power for these devices.
>
> Further, loud passages in program material will drive
> the amplifiers into unstable operation that gives one
> pause for the gnashing of teeth. I've found that a LARGE
> capacitor (like 10,000 uF) really tames them down
> . . . alternatively, an array of ni-mh cells floated
> across the power line work just as well . . . and
> makes the amplifier portable.
>
> Just a heads-up. Class D is one 'wave of the future'
> for not-quite hi-fi audio applications. The prices
> and performance are attractive . . . but there
> are integration issues the user should be aware of.
>
> If plan to or already are fiddling with
> these critters, I'd be pleased to compare notes
> either here on the List or privately.
>
> Bob . . .
Message 11
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| Subject: | Re: Audio Amplifier heads-up |
Message 12
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| Subject: | Re: Ground plane diameter |
At 03:30 PM 2/25/2013, you wrote:
>I'm upgrading avionics in my Glasair and one of the units I'm adding
>is a Garmin GDL-88 for ADS-B out. The antenna I'm using is a Comant
>CI-105 and seeing it's a "plastic" airplane I've been wondering if a
>6" diameter copper disc is large enough for the ground plane or
>should I go a bit larger? TIA
To understand the workings of ground planes under
vertical 1/4-wave radiators (like comm, transponder
and DME) antennas, you need to take a little 'head
trip'.
The older brother to a 1/4-wave antenna fed at the
base is a 1/2-wave antenna fed at the center (aka
VOR/LOC/GS atennas). The 1/2 wave antenna doesn't
need a 'ground' because is has useful places to send
1/2 of the total energy into each of two identical,
complimentary radiators.
Now, take a dipole and turn it up vertically as if
you wanted to use it for comm. Hmmmm . . . hard to
attach the coax to it while insulating the hot
end of the lower element. Okay, bend the lower element
90 degrees. Now the feed point at the antenna
center comes down to skin level on the airplane . . .
but the 'bent' half of the antenna is seriously
compromised for efficiency as it no longer works
in concert with its unmodified counterpart.
Hmmmm . . . how to make the lion's share of the energy
flow into the freely extended portion of the antenna
while reducing a wasteful venture onto the
compromised portion of the antenna? How about adding
a second compromised element? Assume the feed point
impedance of each element is R. Then a dipole in
extended splendor has a feed point impedance of 2R.
You've still got R + R with the compromised dipole
but paralleling two 'crippled' elements at the base
gives you 1/2R + R. We see that energy fed to
this network divides with 1/3 going to the compromised
side and 2/3 to the free element. Let's consider adding
2 more 'compromised' elements. Now we have 1/4R + R.
Great! 4/5ths of the energy goes to the working part
while only 1/5th is left free to roam and be a general
nuisance to your radiation pattern.
Now, if you want to squirt your signal off at an
angle that is closer to the horizon, you can droop
those elements not unlike the antennas seen around
many airports.
http://www.krecoantennas.com/images/gp-155.jpg
Take this exercise to an extreme . . . say 100
'compromised' elements. Now you get 1/100R + R
and only 1% of the energy is left free to be
problematic. Further, 100 compromised elements
look very close to a solid disk of material having
a RADIUS equal to the HEIGHT of the free element.
You sometimes see 100 drooping elements that look
very much like a cone of solid metal.
So, getting back to your question, the IDEAL small
ground plane has a radius equal to the 1/4-wave
distance for the frequency of interest. In the case
of transponders, this works out to 300M meters/sec
divided by 1050 cycles/second times 39.36 inches/meter
times 0.25 wavelength and you get 2.8 inches. Twice
this value is 5.6", the ideal resonant ground plane
for transponder antennas.
Making it just a little bigger because you can is
counter productive. On the other hand, making it
MUCH bigger (like the belly of a metal airplane)
and it begins to approximate a non-resonant, infinite
ground plane which is very good too . . . but a
a whole different ballgame.
The short answer is that for a non-conducting
mounting surface the antenna performs best with
the idealized, 1/4-wave radius disk. If you
could mount it to several square feet of aluminum
it would only slightly better . . . so slight
that you would need to measure the difference
in a well heeled RF lab. So the best recommendation
is go for the 5.6" disk.
Bob . . .
Message 13
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| Subject: | Re: Audio Amplifier heads-up |
At 03:42 PM 2/25/2013, you wrote:
>Have you taken a look at the output RFI? Or is it reasonably well
>filtered in your test PCB? With the highly susceptible nature of
>some flying widgets, I'm curious what your take is.
Not yet. The current application is terrestrial.
I will explore that characteristic in due course.
Bob . . .
Message 14
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| Subject: | Re: Ground plane diameter |
OK, thanks Bob.- It operates on 978 Mhz so I probably could have figured
it out =0Aby breaking out my-ARRL Antenna Book but I guess I was just -
a bit on the lazy =0Aside.=0A=0ABill=0A=0A=0A=0A=0A________________________
________=0AFrom: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
=0ATo: aeroelectric-list@matronics.com=0ASent: Mon, February 25, 2013 8:06:
58 PM=0ASubject: Re: AeroElectric-List: Ground plane diameter=0A=0AAt 03:30
PM 2/25/2013, you wrote:=0A=0AI'm upgrading avionics in my Glasair and one
of the units I'm adding is a Garmin =0AGDL-88 for ADS-B out.- The antenn
a I'm using is a Comant CI-105 and seeing it's =0Aa "plastic" airplane I've
been wondering if a 6" diameter copper disc is large =0Aenough for the gro
und plane or should I go a bit larger?- TIA=0A=0A-- To understand the
workings of ground planes under=0A-- vertical 1/4-wave radiators (like
comm, transponder=0A-- and DME) antennas, you need to take a little 'h
ead=0A-- trip'.=0A=0A-- The older brother to a 1/4-wave antenna fed
at the=0A-- base is a 1/2-wave antenna fed at the center (aka=0A--
VOR/LOC/GS atennas). The 1/2 wave antenna doesn't=0A-- need a 'ground'
because is has useful places to send=0A-- 1/2 of the total energy into
each of two identical,=0A-- complimentary radiators.=0A=0A-- Now,
take a dipole and turn it up vertically as if=0A-- you wanted to use it
for comm. Hmmmm . . . hard to=0A-- attach the coax to it while insulat
ing the hot=0A-- end of the lower element. Okay, bend the lower element
=0A-- 90 degrees. Now the feed point at the antenna=0A-- center com
es down to skin level on the airplane . . .=0A-- but the 'bent' half of
the antenna is seriously=0A-- compromised for efficiency as it no long
er works=0A-- in concert with its unmodified counterpart.=0A=0A-- H
mmmm . . . how to make the lion's share of the energy=0A-- flow into th
e freely extended portion of the antenna=0A-- while reducing a wasteful
venture onto the=0A-- compromised portion of the antenna? How about ad
ding=0A-- a second compromised element? Assume the feed point=0A--
impedance of each element is R. Then a dipole in=0A-- extended splendor
has a feed point impedance of 2R.=0A=0A-- You've still got R + R with
the compromised dipole=0A-- but paralleling two 'crippled' elements at
the base=0A-- gives you 1/2R + R. We see that energy fed to=0A-- th
is network divides with 1/3 going to the compromised=0A-- side and 2/3
to the free element. Let's consider adding=0A-- 2 more 'compromised' el
ements. Now we have 1/4R + R.=0A-- Great! 4/5ths of the energy goes to
the working part=0A-- while only 1/5th is left free to roam and be a ge
neral=0A-- nuisance to your radiation pattern.=0A=0A-- Now, if you
want to squirt your signal off at an=0A-- angle that is closer to the h
orizon, you can droop=0A-- those elements not unlike the antennas seen
around=0A-- many airports.=0A=0A=0A -=0A=0A-- Take this exercise
to an extreme . . . say 100=0A-- 'compromised' elements. Now you get 1/
100R + R=0A-- and only 1% of the energy is left free to be=0A-- pro
blematic. Further, 100 compromised elements=0A-- look very close to a s
olid disk of material having=0A-- a RADIUS equal to the HEIGHT of the f
ree element.=0A-- You sometimes see 100 drooping elements that look=0A
-- very much like a cone of solid metal.=0A=0A-- So, getting back t
o your question, the IDEAL small=0A-- ground plane has a radius equal t
o the 1/4-wave=0A-- distance for the frequency of interest. In the case
=0A-- of transponders, this works out to 300M meters/sec=0A-- divid
ed by 1050 cycles/second times 39.36 inches/meter=0A-- times 0.25 wavel
ength and you get 2.8 inches. Twice=0A-- this value is 5.6", the ideal
resonant ground plane=0A-- for transponder antennas.=0A=0A-- Making
it just a little bigger because you can is=0A-- counter productive. On
the other hand, making it=0A-- MUCH bigger (like the belly of a metal
airplane)=0A-- and it begins to approximate a non-resonant, infinite=0A
-- ground plane which is very good too . . . but a=0A-- a whole dif
ferent ballgame.=0A=0A-- The short answer is that for a non-conducting
=0A-- mounting surface the antenna performs best with=0A-- the idea
lized, 1/4-wave radius disk. If you=0A-- could mount it to several squa
re feet of aluminum=0A-- it would only slightly better . . . so slight
=0A-- that you would need to measure the difference=0A-- in a well
heeled RF lab. So the best recommendation=0A-- is go for the 5.6" disk.
=0A
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