Today's Message Index:
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1. 09:18 AM - Re: LED similar to EL strip (Robert L. Nuckolls, III)
2. 01:05 PM - Re: vhf transponder interference (jappie)
3. 11:19 PM - Re: Blind riveting ground to airframe? (B Tomm)
Message 1
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Subject: | Re: LED similar to EL strip |
At 08:58 PM 3/26/2013, you wrote:
Saw this item and thought of the EL strips that were so noisy. This
is listed as a flat LED.
http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&productId=2153174&catalogId=10001&CID=PDF
I get the impression from some of the recent posts that some seem to
think that LED lights are noisy. THEY ARE NOT NOISY!
The high power leds need to have a current regulated supply, and one
of the more efficient methods of producing a regulated current is to
use a switching supply, which has an oscillator built in. This
oscillator is often the culpret that radiates the RF which gets into
our radio receivers. These regulators can be designed quite easily
to be quiet. Most of the ones that we experimental aircraft builders
are having a noise problem with were originally built for automotive
use where noise in the 120mhz range was not an issue.
Roger
Cool find Roger . . . I'll pursue it.
EL (electroluminescent) lights are essentially
capacitors with a dielectric that emits
light when excited by an alternating electro-static
field of generally 40-200 volts range and 200 to
1000 Hz.
LED lights are solid state diode junctions that
emit light when excited by a current flow in the
forward direction across the junction.
Neither light technology is inherently noisy.
The EL technology requires a DC to AC converter.
It's usually variable to adjust for relative
lamp brightness. LED's run happily on DC excitation
taken directly from the bus . . . again paired
with some technology for varying the current to
the lamp.
Rudimentary controls comprised of series resistance
are inefficient but tolerable for small loads.
The high power LEDs perform best when supplied by
constant current DC to DC sources. These can
be variable under pilot control or fixed depending
on application of the lights.
ALL of our discussions here on the List about
"noisy lights" have centered on high power applications
for LEDs as position lights and more recently, landing
and taxi lights. The solid state lamps are not inherently
noisy but the power supplies needed for efficient
utilization can be and often are objectionably noisy
for use on airplanes.
The discussions have pondered techniques for adapting
commercial off the shelf examples of such products
to our airplanes by first determining if there noise
levels are acceptably low and then applying additional
filters as necessary. It's easy to build power supplies
that are airplane friendly . . . but suppliers of
the attractive COTS products probably couldn't care less
about getting their products onto airplanes.
The item featured in the Jameco catalog has an
interesting form factor reminiscent of an EL light
panel. I'll get one and see what it's all about.
Emacs!
Several readers have noted the proliferation of led strip
lights fitted with multiple surface mounted LEDs.
Here's one of many examples:
http://tinyurl.com/chsx9j2
These are assemblies 3LED/1Resistor modules about
2" in length. Long strips can be cut to length
between modules.
These are very user friendly. I've got plans to
use about 100 feet of these strips in an overhaul
of room and counter lighting in my kitchen.
Bob . . .
Message 2
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Subject: | Re: vhf transponder interference |
Thank you Bob
I did my soldering last weekend with RG-142 but I installed the impedance bushing
not knowing better, anyhow, I don't think it will be harmfull.
JP
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=397176#397176
Message 3
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Subject: | Blind riveting ground to airframe? |
How does the the stainless firewall riveted with aluminum rivets to aluminum
sheet and angle stock play nice together?
Bevan
_____
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Ed
Holyoke
Sent: Tuesday, March 26, 2013 9:35 PM
Subject: Re: AeroElectric-List: Blind riveting ground to airframe?
Stainless and aluminum don't play nice together. The aluminum will donate
ions and corrode. Cad plated steel is the AN way. The cadmium is more anodic
than the aluminum and acts as a sacrificial barrier. Eventually, it has no
more ions to donate and loses it's value as a corrosion preventative. Time
then for new hardware. Another approach would be to prime your hardware and
install it wet.
Ed Holyoke
On 3/26/2013 7:25 AM, Jay Hyde wrote:
Hello Sacha,
I have the same problem in South Africa. For non structural parts I simply
use Metric sized bolts and nuts; usually stainless steel ones to protect
against corrosion. Stainless steel and aluminium have relatively close
galvanic potentials as far as I can see. I have given up trying to source,
or even understand (!) the imperial nut and bolt thread system; its far
easier to walk into a bolt store and ask for M6 x 25mm bolts and M6 nuts. J
For structural parts you must however use AN fasteners and they are not too
difficult to understand (unless you need to order a tap or die.) ; I order
them directly from Aircraft Spruce in the US.
Johannesburg Jay
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Sacha
Sent: 26 March 2013 03:58 PM
Subject: Re: AeroElectric-List: Blind riveting ground to airframe?
Does anyone know what the METRIC equivalent of an AN fastener is and where I
can buy some? I'm in Italy, so preferably somewhere in Europe, though I'm
willing to order from the US if necessary. I've been going nuts (no pun
intended) trying to look for some but can only find a few manufacturers,
nothing for the retail buyer.
On Mar 26, 2013, at 13:42, rayj <raymondj@frontiernet.net> wrote:
Looks like a great source for fasteners. I wanted to be sure the ones I
chose were to an specs. I ended up ordering a big assortment of small AN
screws. If I could have gotten an stuff with 6 lobe recess, I would have
prefered it. Definitely preferable to Phillips.
Raymond Julian
Kettle River, MN.
"And you know that I could have me a million more friends,
and all I'd have to lose is my point of view." - John Prine
On 03/26/2013 07:20 AM, William Schertz wrote:
<mailto:wschertz@comcast.net> <wschertz@comcast.net>
Also note that they carry 100 degree flat head with Torx drive, much nicer
for avoiding stripouts like phillips
Bill Schertz
-----Original Message----- From: Werner Schneider
Sent: Tuesday, March 26, 2013 5:41 AM
Subject: Re: AeroElectric-List: Blind riveting ground to airframe?
<mailto:glastar@gmx.net> <glastar@gmx.net>
Ray checkout http://www.microfasteners.com/catalog/products/SSC.cfm
I replaced nearly all of my Phillips with the 6 lobe screws
Cheers Werner
On 25.03.2013 22:21, rayj wrote:
Agreed. I was looking for some "blessed" #10 hex head bolts because I
prefer a hex head over slotted or phillips screw heads.
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