---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Wed 03/27/13: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 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 _____________________________________ Time: 09:18:17 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 01:05:51 PM PST US Subject: AeroElectric-List: Re: vhf transponder interference From: "jappie" 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 _____________________________________ Time: 11:19:31 PM PST US From: "B Tomm" Subject: RE: AeroElectric-List: 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 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: 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? 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. http://www.matronics.com/Navigator?AeroElectric-List http://forums.matronics.com http://www.matronics.com/contribution ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.