---------------------------------------------------------- M14PEngines-List Digest Archive --- Total Messages Posted Wed 01/06/10: 3 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 08:18 AM - Re: Booster coil (HBaker) 2. 09:06 AM - Re: Tachometer (HBaker) 3. 09:49 AM - Re: Re: Tachometer (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E) ________________________________ Message 1 _____________________________________ Time: 08:18:33 AM PST US Subject: M14PEngines-List: Re: Booster coil From: "HBaker" Hi Mark A picture is worth a thousand words! Henry -------- Currently building a Murphy Moose - any help would be appreciated. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=280362#280362 ________________________________ Message 2 _____________________________________ Time: 09:06:17 AM PST US Subject: M14PEngines-List: Re: Tachometer From: "HBaker" Hi Mark I have a electronics guy hooking up the Horizons tack that I purchased last year, We were going to wire it into the avionics switch, to be turned on after we have started the engine and have switched to mags, because he heard the booster coil is hard on the micro-processor . any thoughts on this?? Henry -------- Currently building a Murphy Moose - any help would be appreciated. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=280371#280371 ________________________________ Message 3 _____________________________________ Time: 09:49:07 AM PST US Subject: RE: M14PEngines-List: Re: Tachometer From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" I have no personal experience with problems in this regard. As in... Booster coil energy damaging the Tach. No one that I know of who has installed this Tach has EVER had this problem. But, he may know something I do not! Who knows? Keep this in mind if you will. The electrical path of the energy supplied by the booster coil for starting, follows a completely different path than the energy that comes from the mag AFTER starting. This is important to understand, so let's continue. The very only things that are used during starting in the mag are: 1. A retarded rotor point that makes contact with the BOOST COIL energy through a slip ring. 2. The mag cap, where the spark plug wires actually connect. THAT IS IT! Nothing else in the mag is used during starting except for the mechanical parts that make the thing rotate when the engine turns. With a good system, you can actually start and run the engine with the starting circuit alone. I am not recommending that you DO this, although I have for testing purposes. There is a very brief period of time during starting where the starter button is pushed, the engine has started on the booster coil energy firing the spark plugs, the mags are turned on (P LEADS BECOME UN-GROUNDED) and there is spark energy from both the mag itself (going to a DIFFERENT contact point on the rotor) AND the boost coil retarded rotor point. So how is this going to impact the P leads and damage a Horizon Tach? I don't see any way that it could, except for one thing, shielding. More on that in a moment. Also, there is no electrical "surge" in these aircraft because there is no collapsing inductive magnetic field pulse from an electrical starter. But now we come to shielding. If you have bad shielding in ANYTHING... That means Booster Coil High Voltage, it is ....in theory .....possible that it could get into the main 28 VDC power source and cause damage to any kind of Avionics. That said, let's go in a different direction for a second. The Horizon Tach hooks to the P leads. The P leads contain a TON of RF noise from the mags. That is why they are shielded. However, the actual P leads themselves... BOTH OF THEM... Run into this Tach. It is entirely possible for this noise energy to go into the Tach, and come back out on the main 28 volt wiring that POWERS this Tach. Now you have this crap getting into everything. Especially if you connect these wires to the exact same circuits that are powering your RADIOS. I am not saying this will happen. The engineers who designed this TACH just HAD to take great efforts to try and prevent this. But I am saying that more than one person has had significant noise problems when using a Horizon Tach, and most ESPECIALLY with Becker Radios. Not ALL mind you, but some. So, my thoughts are that if you are going to hook it up this way, it would be wise to put an RF noise filter on the power leads to the Horizon Tach. Not to keep outside stuff from getting into the Horizon, but to keep stuff in the Horizon from getting out and onto main aircraft power wiring. This can be as simple as using a torroidal core with the power wires wrapped through them several times. Can't find one of those? Go look around for an old computer monitor. Not the flat screen type, the old big ones with a CRT. Look at the cables going to it. One of them will have a big BULGE in the cable. Chop this off and carefully slice it apart. Inside you will find a torroidal core with the wires wrapped through it. They put it there for the same reason I am suggesting putting it on the Horizon Tach power leads. You can also wrap the P leads through one too. Mark -----Original Message----- From: owner-m14pengines-list-server@matronics.com [mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of HBaker Sent: Wednesday, January 06, 2010 12:06 PM Subject: M14PEngines-List: Re: Tachometer --> Hi Mark I have a electronics guy hooking up the Horizons tack that I purchased last year, We were going to wire it into the avionics switch, to be turned on after we have started the engine and have switched to mags, because he heard the booster coil is hard on the micro-processor . any thoughts on this?? Henry -------- Currently building a Murphy Moose - any help would be appreciated. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=280371#280371 ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message m14pengines-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/M14PEngines-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/m14pengines-list Browse Digests http://www.matronics.com/digest/m14pengines-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.