---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Sun 02/08/09: 4 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:46 AM - Light Speed Ignition with OV (ROGER & JEAN CURTIS) 2. 07:08 AM - Re: Light Speed Ignition with OV (Robert L. Nuckolls, III) 3. 03:39 PM - Head sets, iontercoms and Hand helds (jtortho@aol.com) 4. 06:00 PM - Re: Light Speed Ignition with OV (user9253) ________________________________ Message 1 _____________________________________ Time: 05:46:20 AM PST US From: "ROGER & JEAN CURTIS" Subject: AeroElectric-List: Light Speed Ignition with OV There has been discussion recently about Light Speed Ignition with built in OV protection based on a phone conversation with Light Speed. And then someone posted an excerpt from the installation manual which reads in part: "Input voltages above 35 volts or reversed polarity will cause system damage. For this reason it is mandatory that all aircraft using Plasma CD Ignitions are equipped with over-voltage protection in their alternator charging system(s)." I interpret this to mean that there is no crowbar over-voltage protection built into the Light Speed Ignition. Otherwise, how could it be damaged if high voltage is shorted by internal OV protection? And why would it be mandatory that the aircraft electrical system be equipped with OV protection if it is already built into the ignition? I suggest that there was a misunderstanding in the conversation and that Light Speed Ignition systems do NOT have built-in crowbar over-voltage protection. The company should issue a written statement to clarify this issue. Otherwise prospective customers might not want to buy their products if there is a perceived danger that a charging system failure could stop the engine. Joe This is not a perceived danger, as you stated, but a real actual failure reported by more than 1 lister. I agree that the company should issue a statement to clarify their design goals. In the mean time, it appears that pilots should be aware of this potential problem and the power to the Light Speed Ignition systems should be fed through an easily accessible in flight circuit breaker. Roger ________________________________ Message 2 _____________________________________ Time: 07:08:03 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Light Speed Ignition with OV At 07:36 AM 2/8/2009, you wrote: > >There has been discussion recently about Light Speed Ignition with >built in OV protection based on a phone conversation with Light >Speed. And then someone posted an excerpt from the installation >manual which reads in part: >"Input voltages above 35 volts or reversed polarity will cause >system damage. For this reason it is mandatory that all aircraft >using Plasma CD Ignitions are equipped with over-voltage protection >in their alternator charging system(s)." >I interpret this to mean that there is no crowbar over-voltage >protection built into the Light Speed Ignition. Otherwise, how >could it be damaged if high voltage is shorted by internal OV >protection? And why would it be mandatory that the aircraft >electrical system be equipped with OV protection if it is already >built into the ignition? I suggest that there was a >misunderstanding in the conversation and that Light Speed Ignition >systems do NOT have built-in crowbar over-voltage protection. The >company should issue a written statement to clarify this >issue. Otherwise prospective customers might not want to buy their >products if there is a perceived danger that a charging system >failure could stop the engine. >Joe > >This is not a perceived danger, as you stated, but a real actual >failure reported by more than 1 lister. I agree that the company >should issue a statement to clarify their design goals. In the mean >time, it appears that pilots should be aware of this potential >problem and the power to the Light Speed Ignition systems should be >fed through an easily accessible in flight circuit breaker. This is one example of the important activities for crafting and qualifying systems on TC aircraft. This exercise offers decades of valuable lessons-learned. The conversations that have evolved around this topic are excellent examples of how much "wobble" there is moving toward complete understanding when we're not privy to the details of a particular product's design. On the TC side of the house it's not uncommon for an OEM airframer to have complete sets of drawings for as-supplied products in the "vendor files". Of course, these are protected under the standard non-disclosure agreements. Access to these files is a critical component of seamless system integration and troubleshooting of fielded systems. Not having access to internal details gives rise to discussions not unlike those we're having now about Lightspeed . . . and those we've had in the past about critical characteristics of IR alternators. The point I've emphasized in all of these discussions is that intimate knowledge of the inner workings of a product is absolutely required for competent systems folks to do their job. The marketing hype and 4-color brochures are useless when it comes to qualifying a device on the aircraft and/or preventing/fixing problems in the field. There is risk when a customer is forced to "interpret" the meaning of words to arrive at some rudimentary understanding. Lightspeed has a free-marked duty to give you lucid answers to all of your questions . . . just as you have a right to reject their product based on perceptions of value and risk. Risk pushed upon you as a product of holding critical details incommunicado is not acceptable. Bob . . . ----------------------------------------) ( . . . a long habit of not thinking ) ( a thing wrong, gives it a superficial ) ( appearance of being right . . . ) ( ) ( -Thomas Paine 1776- ) ---------------------------------------- ________________________________ Message 3 _____________________________________ Time: 03:39:21 PM PST US Subject: AeroElectric-List: Head sets, iontercoms and Hand helds From: jtortho@aol.com This seems that it should have an easy answer, but In this area I am a neophyte. In my 2 seat? project, I have a Avcom AC6PA intercom. I was going to run the output of a Nav 122 into a switch on the audio input of the intercom.? This should let me monitor this as Nav 1 without an audio?panel. I also have a hand held, the sporty? JD200. What would be the repercussions of wiring the hand held as one of the passenger head sets.? The real goal is being able to hear over the intercom.? The? hand held speaker port expecting to see a 150 ohm head set, but would instead see the 5 volt bias? for the microphone.? Would this work at all , or over/under drive the intercom.? I am afraid I don't know what amplitude of signal is expected or supplied.? Going in the other direction would be a similar mismatch.? The hand transmitter would be seldom used , in my plan, so driving that via the intercom would be less important, and I would expect to use the integral PTT. So would this work, or would I make expensive smoke? JimT ________________________________ Message 4 _____________________________________ Time: 06:00:33 PM PST US Subject: AeroElectric-List: Re: Light Speed Ignition with OV From: "user9253" Thanks to Bob and Roger for the informative replies. Roger, You mentioned other postings about over-voltage conditions disabling the Lightspeed ignition. I would like to read about them if you happen to have a link to the posting. I do not read AeroElectric everyday and missed the postings. I did read about a Lightspeed ignition that failed because of overheating. Thanks, Joe -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=229278#229278 ------------------------------------------------------------------------------------- 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.