Today's Message Index:
----------------------
1. 10:16 AM - Re: LED landing light filter experiment (SWAN MGT LLC/M WYNN)
2. 11:04 AM - Re: LED landing light filter experiment (Bob McCallum)
3. 01:28 PM - Re: LED landing light filter experiment (Robert L. Nuckolls, III)
4. 02:14 PM - Re: LED landing light filter experiment (James Kilford)
5. 02:20 PM - Re: LED landing light filter experiment (SWAN MGT LLC/M WYNN)
6. 06:36 PM - Re: LED landing light filter experiment (Robert L. Nuckolls, III)
7. 06:48 PM - Re: LED landing light filter experiment (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: LED landing light filter experiment |
Bob:
1. Why do we LED DIY-fer's need an LED driver for a 12 vdc [forward
voltage] LED [10 Watt] when we have a clean 12 vdc source [aircraft]?
Answering my own question, maybe: Is it primarily to provide minimum
ripple current to the driven LED?
2. What is the simplest way to detect HF noise from an LED; maybe an FM
or AM radio receiver, or better yet, an aircraft nav/com receiver?
Trying to KIS.. ;)
Thanks in advance,
Mike W
Moab
*********
----- Original Message -----
From: Robert L. Nuckolls, III
To: aeroelectric-list@matronics.com
. . .
Message 2
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| Subject: | LED landing light filter experiment |
Because an LED is not a voltage driven device. It is a current driven devic
e. The required "driver" is a current source. If your 10 watt LED has a for
ward voltage drop of 2 volts and is designed to be driven by lets say 5 amp
s of current then without a current driver to regulate that current you wou
ld need to add a resistor to drop the other 10 volts of your 12 volt source
. This means 10 volts being dropped by 5 amps through a resistor or 50 watt
s of heat. (Pretty big HOT resistor) So much for the power saving of the LE
D. Your "10 watt" LED is now consuming 60 watts. If you use a "driver" to r
egulate the current the losses within the driver are minimal and your 10 wa
tt LED consumes approximatly 10 watts. Also with a resistor to regulate cur
rent what happens when your voltage is 14.5 being supported by the alternat
or? Now you power consumption goes even higher and you risk overdriving the
LED wheras with a "driver" the current remains constant at the design leve
l.
Bob McC
(I'm sure the "other" Bob can explain it better=2C but that's the jist of i
t.)
From: wynaire@citlink.net
Subject: Re: AeroElectric-List: LED landing light filter experiment
Bob:
1. Why do we LED DIY-fer's need an LED driver for a
12 vdc [forward voltage] LED [10 Watt] when we have a clean 12 vdc source
[aircraft]?
Answering my own question=2C maybe: Is it primarily
to provide minimum ripple current to the driven LED?
2. What is the simplest way to detect HF noise from
an LED=3B maybe an FM or AM radio receiver=2C or better yet=2C an aircraft
nav/com receiver?
Trying to KIS.. =3B)
Thanks in advance=2C
Mike W
Moab
*********
----- Original Message -----
From:
Robert L. Nuckolls=2C III
To: aeroelectric-list@matronics.com
. . .
Message 3
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| Subject: | Re: LED landing light filter experiment |
>
>
>2. What is the simplest way to detect HF noise from an LED; maybe an
>FM or AM radio receiver, or better yet, an aircraft nav/com receiver?
>Trying to KIS.. ;)
There was a time when an airplane might have
several kinds of receivers vulnerable to radiated
and conducted signals from potential antagonists.
In order of spectrum they would have included
ADF/AM Broadcast receivers, Loran, HF communications,
Marker Beacon, VOR/LOC, VHF Comm, Glideslope
all topped off with DME, transponders and GPS.
That list is certainly diminished. Most OBAM
builders radios of interest are limited to
VOR/LOC, VHF Comm, Glideslope, Xpndr and
GPS. Each potential victim presents a unique
signature and magnitude for immunity to extraneous
signals.
The easiest way to test for vulnerability is
in flight and testing each potential victim
at the fringes of its normal performance range.
See if turning the antagonist on/off makes any
observable difference in performance.
This real-life/in-situ A-B comparison requires
no calibration of measurement. Obviously, the
hand held or bench receiver with some sort of
'sniffer' antenna can be used to see if any noise
can be detected . . . but the noise being heard
may not be so strong as to be significant.
The tests I'm performing now use a filtered and
an unfiltered LED assembly. The detector is a full
coverage communications receiver with a precision
attenuator between the receiver and the sense
antenna. The filtered lamp assembly is fired up
and a noise level measurement taken on the receiver's
strength meter. I then turn on the unfiltered
device (which is stronger) and then switch in
values of attenuation until the receiver sees
the same level of noise. The value of attenuation
tells me how GOOD the filter is. I.E. the noise
a some frequency of interest is reduced by XX
dB. 30 dB is a factor of 1000 reduction.
Now, putting real numbers on those signal strengths
is a separate experiment. The experiment cited
only speaks to filter effectiveness and says nothing
about gross numbers for the radiated noise.
Hand held, un-calibrated detectors are very handy
for detecting the presence of noise and to a
limited degree, measuring the efficacy of a noise
reduction technique. The REAL test is to fly it
and see how the antagonist system affects the
victim in a weak signal situation. A noise you
can detect with a hand-held transceiver may not
be significant in the real world.
Bob . . .
Bob . . .
Message 4
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| Subject: | Re: LED landing light filter experiment |
Thanks Bob. Appreciate the explanation.
On the subject of Eric, I seem to recall that it was he who recommended
flexible LED strips instead of my noisy EL wire for cockpit lighting.
These run on 12V... are they likely to produce noise in the same way then?
I'm guessing not, because in testing them the other day, they produced the
right level of light at about 7.5V and drew hardly any current at all --
less then 0.01A, according to my bench PSU.
James
On 23 January 2013 23:06, Robert L. Nuckolls, III <
nuckolls.bob@aeroelectric.com> wrote:
> At 01:54 PM 1/23/2013, you wrote:
>
> Nice work Bob. =C3=82 Do you mind me asking... what is about these LED li
ghts
> that makes them so noisy? =C3=82 In my head, LEDs are completely inert an
d
> therefore wouldn't create any interference.
>
>
> You are, of course, correct. The LEDs are very quiet.
> Not zero noise . . . the electrical activity in the
> light emitting junction is pretty frenetic. But
> the aperture (antenna area) is very tiny so it's
> hard to detect . . . much less a risk for a noise
> source.
>
> The problem is that LEDs are CURRENT operated
> devices. You're probably familiar with the ubiquitous
> resistor wired in series with an LED to SET the
> current flowing through the device. To light an
> red LED (typical voltage drop on the order of
> 2 volts) from a 14v bus, you have to pick a resistor
> that causes the desired LED current to flow (30 mA)
> with a DROP of 12 volts. This means that the series
> resistor dissipates 6 TIMES as much energy as the
> LED . . . but it's so small as to be insignificant.
>
> POWER LEDs will demand much larger current values.
> Consider this device
>
> http://tinyurl.com/a2sggv4
>
> which is rated at 10 watts. Note that it's rated
> to operate at 3 amps so one would guess that
> the operating voltage is about 3.3 volts (typical
> for white). So, using a simple series resistor
> for 14 volt systems would dissipate 30 watts . . .
> NOT insignificant.
>
> The elegant solution demands a special kind of
> DC to DC converter. VARIABLE voltage input
> (say 10 to 16 volts) and CONSTANT current
> output (3 A). Now, we can hook perhaps 3 to
> 6 lamps in series (10 to 20 volt operation)
> but at a constant current.
>
> This bit of electronic magic is ALWAYS
> noisy. Your computer, tv, and countless
> other appliances have similar power supplies
> but they're generally qualified to FCC part
> 15 rules for expected but limited emissions.
> No so with LED lamp fixtures from Fuzzy Joe's
> Motorcycle shop . . . or 24xydiy.com either.
>
> We had some discussions here on the list about
> LED position lights wherein a number of
> builders using a particular DIY kit were
> experiencing radio noise from the LuxDrive
> power supplies recommended for the installation.
>
> This prompted development of the filtered version
> of the LuxDrive part which I've offered now
> for several years
>
> [image: []]
>
> This board is the foundation for the experimental filter
> I crafted for the aforementioned experiment. This jeeped
> experiment may not be the ideal way to go for an on-purpose
> filter but then, the then, the boards are already fabricated
> and in stock.
>
> Our very own Eric Jones offers an LED based tail light
>
> http://tinyurl.com/b377jtv
>
> Which has enjoyed the benefits of creative tailoring to
> the task and generates no objectionable noises.
>
>
> **
>
> ** Bob . . .
>
> *
>
===========
===========
===========
===========
> *
>
>
Message 5
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| Subject: | Re: LED landing light filter experiment |
Thanks Bob.
I'm with you for about 75% of the electro-magic here.
My real world [table top] on the test bench: My design rated 12 vdc
6000k LED [with heat sink attached] is working very well "pulling 10 vdc
and 500 ma." Power supply is a Micronta Dual Tracking Adjustable DC
Power Supply. If I understand you correctly, the main (only?) reason
that I should add another component [the LED driver] is to insure a
steady-state current supply to my LED? PS: My final lighting goal is
to use these (mounted under FAA-PMA red, green & clear glass lens) for
wing-tip and tail nav lights, and to strobe them (white) at the same
positions.
Your thoughts are sincerely appreciated. There is only so much that one
can gain from studying texts... ;)
Mike
********
----- Original Message -----
From: Bob McCallum
To: aeroelectric-list@matronics.com
Sent: Friday, January 25, 2013 12:03 PM
Subject: RE: AeroElectric-List: LED landing light filter experiment
Because an LED is not a voltage driven device. It is a current driven
device. The required "driver" is a current source. If your 10 watt LED
has a forward voltage drop of 2 volts and is designed to be driven by
lets say 5 amps of current then without a current driver to regulate
that current you would need to add a resistor to drop the other 10 volts
of your 12 volt source. This means 10 volts being dropped by 5 amps
through a resistor or 50 watts of heat. (Pretty big HOT resistor) So
much for the power saving of the LED. Your "10 watt" LED is now
consuming 60 watts. If you use a "driver" to regulate the current the
losses within the driver are minimal and your 10 watt LED consumes
approximatly 10 watts. Also with a resistor to regulate current what
happens when your voltage is 14.5 being supported by the alternator? Now
you power consumption goes even higher and you risk overdriving the LED
wheras with a "driver" the current remains constant at the design level.
Bob McC
(I'm sure the "other" Bob can explain it better, but that's the jist
of it.)
-------------------------------------------------------------------------
-----
From: wynaire@citlink.net
To: aeroelectric-list@matronics.com
Subject: Re: AeroElectric-List: LED landing light filter experiment
Date: Fri, 25 Jan 2013 11:14:30 -0700
Bob:
1. Why do we LED DIY-fer's need an LED driver for a 12 vdc [forward
voltage] LED [10 Watt] when we have a clean 12 vdc source [aircraft]?
Answering my own question, maybe: Is it primarily to provide minimum
ripple current to the driven LED?
2. What is the simplest way to detect HF noise from an LED; maybe an
FM or AM radio receiver, or better yet, an aircraft nav/com receiver?
Trying to KIS.. ;)
Thanks in advance,
Mike W
Moab
*********
----- Original Message -----
From: Robert L. Nuckolls, III
To: aeroelectric-list@matronics.com
. . .
-List"
target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
http://forums.matronics.com
="_blank">http://www.matronics.com/contribution
Message 6
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| Subject: | Re: LED landing light filter experiment |
At 04:13 PM 1/25/2013, you wrote:
>Thanks Bob. =C2 Appreciate the explanation. =C2
>
>On the subject of Eric, I seem to recall that it
>was he who recommended flexible LED strips
>instead of my noisy EL wire for cockpit lighting. =C2
>
>These run on 12V... are they likely to produce noise in the same way then?
=C2
No . . . those are the same kind of strips I was
talking about some months back. I've got about
8 feet of that strip material in two rows on the
' under side of a kitchen cabinet to replace a 40-year
old, 18W fluorescent fixture. These strips
are an array of 3 lamps and a resistor in
series parallel with each trio spread out over
about 2" of strip. Are these red lights? Usable
light at 7.5 volts suggests that the threshold
of 2v x 3 lamps (6v) gives you about 1.5 volts
of drop across the installed resistor to set
the operating current.
>I'm guessing not, because in testing them the
>other day, they produced the right level of
>light at about 7.5V and drew hardly any current
>at all -- less then 0.01A, according to my bench PSU.
Yep. These lamps are biased up using the 'simple' but
inefficient configuration where the losses are
acceptably insignificant. No noisy switch
mode power supply necessary.
The lamps we're wrestling with are arrays in the
25 to 35 watt class used for position lights,
landing/taxi lights and perhaps strobes.
They DO have power supplies that WILL be noisy
if not properly filtered.
Bob . . .
>James
>
>
>On 23 January 2013 23:06, Robert L. Nuckolls,
>III
><<mailto:nuckolls.bob@aeroelectric.com>nuckolls.bob@aeroelectric.com>
wrote:
>At 01:54 PM 1/23/2013, you wrote:
>>Nice work Bob. =C3=82 Do you mind me asking... what
>>is about these LED lights that makes them so
>>noisy? =C3=82 In my head, LEDs are completely inert
>>and therefore wouldn't create any interference.
>
>=C2 You are, of course, correct. The LEDs are very quiet.
>=C2 Not zero noise . . . the electrical activity in the
>=C2 light emitting junction is pretty frenetic. But
>=C2 the aperture (antenna area) is very tiny so it's
>=C2 hard to detect . . . much less a risk for a noise
>=C2 source.
>
>=C2 The problem is that LEDs are CURRENT operated
>=C2 devices. You're probably familiar with the ubiquitous
>=C2 resistor wired in series with an LED to SET the
>=C2 current flowing through the device. To light an
>=C2 red LED (typical voltage drop on the order of
>=C2 2 volts) from a 14v bus, you have to pick a resistor
>=C2 that causes the desired LED current to flow (30 mA)
>=C2 with a DROP of 12 volts. This means that the series
>=C2 resistor dissipates 6 TIMES as much energy as the
>=C2 LED . . . but it's so small as to be insignificant.
>
>=C2 POWER LEDs will demand much larger current values.
>=C2 Consider this device
>
><http://tinyurl.com/a2sggv4>http://tinyurl.com/a2sggv4
>
>=C2 which is rated at 10 watts. Note that it's rated
>=C2 to operate at 3 amps so one would guess that
>=C2 the operating voltage is about 3.3 volts (typical
>=C2 for white). So, using a simple series resistor
>=C2 for 14 volt systems would dissipate 30 watts . . .
>=C2 NOT insignificant.
>
>=C2 The elegant solution demands a special kind of
>=C2 DC to DC converter. VARIABLE voltage input
>=C2 (say 10 to 16 volts) and CONSTANT current
>=C2 output (3 A). Now, we can hook perhaps 3 to
>=C2 6 lamps in series (10 to 20 volt operation)
>=C2 but at a constant current.
>
>=C2 This bit of electronic magic is ALWAYS
>=C2 noisy. Your computer, tv, and countless
>=C2 other appliances have similar power supplies
>=C2 but they're generally qualified to FCC part
>=C2 15 rules for expected but limited emissions.
>=C2 No so with LED lamp fixtures from Fuzzy Joe's
>=C2 Motorcycle shop . . . or=C2 <http://24xydiy.com>24xydiy.com either.
>
>=C2 We had some discussions here on the list about
>=C2 LED position lights wherein a number of
>=C2 builders using a particular DIY kit were
>=C2 experiencing radio noise from the LuxDrive
>=C2 power supplies recommended for the installation.
>
>=C2 This prompted development of the filtered version
>=C2 of the LuxDrive part which I've offered now
>=C2 for several years
>
>[]
> =C2
>
>=C2 This board is the foundation for the experimental filter
>=C2 I crafted for the aforementioned experiment. This jeeped
>=C2 experiment may not be the ideal way to go for an on-purpose
>=C2 filter but then, the then, the boards are already fabricated
>=C2 and in stock.
>
>=C2 Our very own Eric Jones offers an LED based tail light
>
><http://tinyurl.com/b377jtv>http://tinyurl.com/b377jtv
>
>=C2 Which has enjoyed the benefits of creative tailoring to
>=C2 the task and generates no objectionable noises.
>
>
>=C2 Bob . . .
>
>
>ist" target="_blank">http://www.matronics.com/Navigator?AeroElectric-List
>
>tp://forums.matronics.com
>
>_blank">http://www.matronics.com/contribution
>
>
><http://www.matronics.com/Navigator?AeroElectric-List>http://www.matronics.
com/Navigator?AeroElectric-List
><http://www.matronics.com/contribution>http://www.matronics.com/contributio
n
>
>
>No virus found in this message.
>Checked by AVG - <http://www.avg.com>www.avg.com
Bob . . .
Message 7
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| Subject: | Re: LED landing light filter experiment |
At 04:19 PM 1/25/2013, you wrote:
>Thanks Bob.
> I'm with you for about 75% of the electro-magic here.
>My real world [table top] on the test bench: My design rated 12 vdc
>6000k LED [with heat sink attached] is working very well "pulling 10
>vdc and 500 ma." Power supply is a Micronta Dual Tracking
>Adjustable DC Power Supply. If I understand you correctly, the main
>(only?) reason that I should add another component [the LED driver]
>is to insure a steady-state current supply to my LED? PS: My final
>lighting goal is to use these (mounted under FAA-PMA red, green &
>clear glass lens) for wing-tip and tail nav lights, and to strobe
>them (white) at the same positions.
>
>Your thoughts are sincerely appreciated. There is only so much
>that one can gain from studying texts... ;)
Are you using any series resistance in your installtion?
How do you intend to establish and maintain the desired
500 mA operating point? What the rated operating current
for the device. Are these white lights that you're going
to filter into red and green? Keep in mind that filters
of white light are VERY inefficient. They block a majority
of the lamp's total output allowing only the desired color
to pass. If you use leds designed to produce red and green
light, then no filtering (with attendant losses) are
necessary.
But assuming that you DO use three such arrays at 500
ma each. Then you need to drop about 5 volts in a resistor
in series with each array for 2.5 watts each. That's
7.5 watts tossed off in heat for each fixture with 15 watts
being used by the lamps. Should the alternator quit,
your bus drops to 12v and you now bias each array at
only 200 mA for a 60% drop in light output.
Now, if you hook all the lamps in series and power them
with a 500 mA constant current switchmode supply, the
light output can remain constant throughout an operating
range of 10 to 15 volts for the bus with only a couple of
watts tossed off by the supply. That's what these guys
do for the OBAM aircraft position lights that were being
discussed here on the list a few years back. This particular
supply will put out any practical excitation value between
100 and 1000 mA . . . and is filtered.
https://matronics.com/aeroelectric/Catalog/9051s.jpg
Bob . . .
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