---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 11/02/07: 15 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 05:18 AM - Re: 496 Audio (Robert Feldtman) 2. 05:29 AM - Re: WTB Crystal Radio (Dan Billingsley) 3. 06:04 AM - Re: For Sale BMA EFIS One (Roger Bentlage) 4. 06:21 AM - Re 496 Audio (emrath@comcast.net) 5. 07:01 AM - Re: For Sale BMA EFIS One (Giffen Marr) 6. 10:48 AM - Re: Wig Wag and keep warm (Vernon Little) 7. 12:32 PM - Re: WTB Crystal Radio (Eric M. Jones) 8. 02:57 PM - Final Review (Terry Miles) 9. 03:51 PM - Re: Final Review (Matt Prather) 10. 04:59 PM - Re: 496 Audio (Kenneth Melvin) 11. 05:24 PM - Re: Final Review (Robert Feldtman) 12. 05:42 PM - Re: Final Review (Gilles Thesee) 13. 06:01 PM - Re: Re: WTB Crystal Radio (Dan Billingsley) 14. 06:33 PM - Re: Final Review (Terry Watson) 15. 07:28 PM - Re: Final Review (Terry Miles) ________________________________ Message 1 _____________________________________ Time: 05:18:40 AM PST US From: "Robert Feldtman" Subject: Re: AeroElectric-List: 496 Audio I'd try one half the transformer. use the center tap for ground and one of the other ones. that would be 500 ohms. - pretty dang close bobf On 11/2/07, Dave Saylor wrote: > > Marty and all, > > We learned a bunch today about audio out from the Garmin 496 that could be > helpftul. > > I had a harness built by Stark to allow me to put audio from the > power/data chord from a 2/3/496 into unswitched audio in my GMA340 audio > panel. Seemed like a simple thing, but we never got any audio from the > power/data chord. Audio jack, yes, data chord, no. > > Turns out the audio from the power/data cable is to drive an 8 ohm > speaker. I learned that by taking apart a Garmin 12V adapter/speaker and > reading the back of the $.05 speaker inside: Made in China, 8 Ohms, 2/3W. > > The audio panel was looking for a 600 ohm input. > > Interestingly, Garmin told told both John and me that the only audio > coming out of the 496, in aviation mode, was from the audio jack(3/496s have > a 1/8" audio jack, which outputs XM audio, and all the warnings, as well as > "Voice +" and "Voice -" wires in the power/data cable). Garmin said not > even to bother trying to get audio from the Voice wires while in aviation > mode. It did not exist. > > Well, it does exist because it plays just fine with the speaker/12V > adapter plugged in. I put the unit in sim mode and flew into a mountain. > The speaker gives every warning you would expect, and the "Sound" page of > the Setup menu controls the audio as you would expect. > > With a jack inserted into the audio plug, the XM audio is turned off to > the power/data chord but all the warnings still come through. Which is > nice, because if you wire the unit per Garmin's advice, and run the audio > jack into the music input of the audio panel, your terrain warnings will get > muted by intercom activity or incoming transmissions. I want to know about > those pesky mountains, even if it interupts music playing in the > background... > > Now my problem is to figure out how to convert the 8 ohm signal from the > power/data chord to 600 ohms. I guess I need a transformer. I found a 8 > ohm to 1000 ohm, with center tap, at radio shack...can anyone tell me if > that will work? How do I wire it? > > Dave Saylor > AirCrafters LLC > 140 Aviation Way > Watsonville, CA > 831-722-9141 > 831-750-0284 CL > www.AirCraftersLLC.com > > ________________________________ Message 2 _____________________________________ Time: 05:29:12 AM PST US From: Dan Billingsley Subject: Re: AeroElectric-List: WTB Crystal Radio Robert, Sounds like you were hooked at quite a young age. Something about the radio sets that is still magic to me...easy to get the high school kids fired up. The site for Dave's Radios looks good. Have you built one of them using the 6418 tube? I would certainly like to try out your module when they are finished. Thanks again, Dan 11434 E Portal Ave Mesa, AZ 85212 "Robert L. Nuckolls, III" wrote: At 07:05 PM 11/1/2007 -0700, you wrote: >Robert, Thanks a bunch for the info...I ordered the book you mentioned as >it looks like a kick to try and make our own stuff. The kids are currently >finishing up their first attempts at crystal radios. Thanks to Ed Larson >here on the list they have variablle caps to tie in. He sent me a whole >box of various sizes. We were out today on the football field and found 4 >radios that worked...quite faint...but it was enough to get them worked >up. We are going to build a one or two transistor amp to add to them. That >will get them into making a PCB. Thanks again, Dan Billingsley >Building a Kitfox-IV >http://www.azshowersolutions.com/Build1.html I've ordered one too. I've been 'building' since the 4th grade when I listened to Ike's election returns on the first crystal set I built from a kit. I've nearly always lived near Wichita's 5KW AM station . . . easy to get strong signals, hard to get anyone else. I've inherited a house from my father in Medicine Lodge, KS . . . lots of miles from any AM BC station. I've become interested in seeing what can be heard from afar with a reasonable antenna system and high Q tuning. I purchased some 6418 vacuum tubes . . . See: http://www.schmarder.com/radios/tube/6418.htm I'm in the process of packaging the 6418 circuitry into one of my standard product packages. See: http://www.aeroelectric.com/Pictures/Products/A15_Package.jpg Everything but batteries, regen pot, tuning caps and inductors will be in this package. The BIG variability in performance is configuration of tuning sections/antenna. I thought it would be useful to have the constants packaged in a robust module that allows fast, low-risk assembly of the variables. If you'd like one of these modules to play with, I'll send you one when they're done. Bob . . . ________________________________ Message 3 _____________________________________ Time: 06:04:21 AM PST US Subject: AeroElectric-List: Re: For Sale BMA EFIS One From: "Roger Bentlage" I am selling a new (installed and works fine but never flown) BMA EFIS One, no engine sensors, for $5,500. Roger 242-535-7121 Read this topic online here: http://forums.matronics.com/viewtopic.php?p=143355#143355 Attachments: http://forums.matronics.com//files/instrument_panel_2_1_664.jpg ________________________________ Message 4 _____________________________________ Time: 06:21:23 AM PST US From: emrath@comcast.net Subject: AeroElectric-List: Re 496 Audio Dave, thanks for your interest in this, I hope there is a solution. Like you, the thought of the warnings being muted by virtue of using the music jack to audio input on the GMA340 is not to my liking either. Marty Time: 11:03:06 PM PST US From: "Dave Saylor" Subject: AeroElectric-List: 496 Audio Marty and all, We learned a bunch today about audio out from the Garmin 496 that could be helpftul. I had a harness built by Stark to allow me to put audio from the power/data chord from a 2/3/496 into unswitched audio in my GMA340 audio panel. Seemed like a simple thing, but we never got any audio from the power/data chord. Audio jack, yes, data chord, no. Turns out the audio from the power/data cable is to drive an 8 ohm speaker. I learned that by taking apart a Garmin 12V adapter/speaker and reading the back of the $.05 speaker inside: Made in China, 8 Ohms, 2/3W. The audio panel was looking for a 600 ohm input. Interestingly, Garmin told told both John and me that the only audio coming out of the 496, in aviation mode, was from the audio jack(3/496s have a 1/8" audio jack, which outputs XM audio, and all the warnings, as well as "Voice +" and "Voice -" wires in the power/data cable). Garmin said not even to bother trying to get audio from the Voice wires while in aviation mode. It did not exist. Well, it does exist because it plays just fine with the speaker/12V adapter plugged in. I put the unit in sim mode and flew into a mountain. The speaker gives every warning you would expect, and the "Sound" page of the Setup menu controls the audio as you would expect. With a jack inserted into the audio plug, the XM audio is turned off to the power/data chord but all the warnings still come through. Which is nice, because if you wire the unit per Garmin's advice, and run the audio jack into the music input of the audio panel, your terrain warnings will get muted by intercom activity or incoming transmissions. I want to know about those pesky mountains, even if it interupts music playing in the background... Now my problem is to figure out how to convert the 8 ohm signal from the power/data chord to 600 ohms. I guess I need a transformer. I found a 8 ohm to 1000 ohm, with center tap, at radio shack...can anyone tell me if that will work? How do I wire it? Dave Saylor AirCrafters LLC 140 Aviation Way Watsonville, CA 831-722-9141 831-750-0284 CL www.AirCraftersLLC.com
Dave, thanks for your interest in this, I hope there is a solution.  Like you, the thought of the warnings being muted by virtue of using the music jack to audio input on the GMA340 is not to my liking either.
Marty
 
Time: 11:03:06 PM PST US
From: "Dave Saylor" <Dave@AirCraftersLLC.com>
Subject: AeroElectric-List: 496 Audio

Marty and all,

We learned a bunch today about audio out from the Garmin 496 that could be
helpftul.

I had a harness built by Stark to allow me to put audio from the power/data
chord from a 2/3/496 into unswitched audio in my GMA340 audio panel.  Seemed
like a simple thing, but we never got any audio from the power/data chord.
Audio jack, yes, data chord, no.

Turns out the audio from the power/data cable is to drive an 8 ohm speaker.
I learned that by taking apart a Garmin 12V adapter/speaker and reading the
back of the $.05 speaker inside: Made in China, 8 Ohms, 2/3W.

The audio panel was looking for a 60 0 ohm input.

Interestingly, Garmin told told both John and me that the only audio coming
out of the 496, in aviation mode, was from the audio jack(3/496s have a 1/8"
audio jack, which outputs XM audio, and all the warnings, as well as "Voice
+" and "Voice -" wires in the power/data cable).  Garmin said not even to
bother trying to get audio from the Voice wires while in aviation mode.  It
did not exist.

Well, it does exist because it plays just fine with the speaker/12V adapter
plugged in.  I put the unit in sim mode and flew into a mountain.  The
speaker gives every warning you would expect, and the "Sound" page of the
Setup menu controls the audio as you would expect.

With a jack inserted into the audio plug, the XM audio is turned off to the
power/data chord but all the warnings still come through.  Which is nice,
because if you wire the unit per Garmin's advice, and run the audio jack
into the music input of the audio panel, your terrain warnings will get
muted by intercom activity or incoming transmissions.  I want to know about
those pesky mountains, even if it interupts music playing in the
background...

Now my problem is to figure out how to convert the 8 ohm signal from the
power/data chord to 600 ohms.  I guess I need a transformer.  I found a 8
ohm to 1000 ohm, with center tap, at radio shack...can anyone tell me if
that will work?  How do I wire it?

Dave Saylor
AirCrafters LLC
140 Aviation Way
Watsonville, CA
831-722-9141
831-750-0284 CL
www.AirCraftersLLC.com

 
________________________________ Message 5 _____________________________________ Time: 07:01:48 AM PST US From: "Giffen Marr" Subject: Re: AeroElectric-List: For Sale BMA EFIS One Your absolutely right, however this new BMA EFIS/One Ver 3 has the second screen, which is a $3000 option for a new the EFIS/0ne Gen 4 and $2600 for the smaller EFIS 2. Still a good savings over the current versions. Make me an offer. Giffen Marr 817-306-9592 617-223-9671 Cell ________________________________ Message 6 _____________________________________ Time: 10:48:35 AM PST US From: "Vernon Little" Subject: RE: AeroElectric-List: Wig Wag and keep warm Thanks Bob. I put the inrush limiters in circuit as a switch saver as opposed to a lamp saver. I've had two Carling switch failures in the first 100 hours-- one Master Switch and the other in my Strobe circuit. The Master had loose rivets that hold the fast-on tabs, while the Strobe switch (which also had a loose rivet) overheated and cooked one terminal. Switch resistance had increased significantly, and I believe the Strobe PSU draws more current at lower voltages, leading to a thermal runaway in the switch. Since then, I've inspected all of my switches for loose rivets and put the inrush current limiters on the landing/taxi lights. I did return one of the switches to the vendor but never heard back with a failure analysis. The inrush limiters don't have much effect on maximum lamp brightness, but slowing the wig-wag flasher down sure did. Vern -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert L. Nuckolls, III Sent: November 1, 2007 11:25 AM Subject: RE: AeroElectric-List: Wig Wag and keep warm --> At 09:50 AM 11/1/2007 -0700, you wrote: > > >I found that the flash rate of the SSF-1 was a bit too fast for my >lamps to come up to full brightness. It's a simple mod to replace the >internal electrolytic capacitor with one of higher value (I think I >doubled the value of mine). My issue may have been exacerbated by the >inrush current limiters (ntc thermistors) that I have in series with >the lighting circuits. Good data point Vern. I'd heard that before but without specifics as to what the builder did about it. I think he pitched the SSF-1 flasher and substituted something else. I don't think inrush limiters would affect timing on this device . . . but it's certain that the inrush limiters have more to do with mitigating initial turn-on glitches to the bus than for extending bulb life. Bob . . . ---------------------------------------- ( "Problems are the price of progress. ) ( Don't bring me anything but trouble. ) ( Good news weakens me." ) ( -Charles F. Kettering- ) ---------------------------------------- ________________________________ Message 7 _____________________________________ Time: 12:32:59 PM PST US Subject: AeroElectric-List: Re: WTB Crystal Radio From: "Eric M. Jones" You guys...Darned I've spent half a day Googling Xtal sets. A MUST SEE: http://www.wynterarchtops.com/radios/index.htm I hate to see anyone build a crystal set and cheap-out by buying the variable capacitor. There's no magic in capacitors. A roll of foil and some scissors will make one in a pinch. There is a long history of capacitors in strange forms. And if it doesn't have a cat's whisker and a galena crystal....shame on you. One of my pet projects (after I finish the Glastar....) is to build crytal sets along the lines of a Captain Nemo fantasy. It is entirely possible to build a an AM radio receiver using nothing you couldn't buy in AD 1200. "Inventor: A person who makes an ingenious arrangement of wheels, levers and springs, and believes it civilization." --Ambrose Bierce -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=143432#143432 ________________________________ Message 8 _____________________________________ Time: 02:57:19 PM PST US From: "Terry Miles" Subject: AeroElectric-List: Final Review Bob, and all, I have just completed a Velocity. She just passed the FAA cert and, I am going thru the process once more of looking at all of my work and hopefully asking all the right questions. I have built a Velocity XLRG. She has a 300 HP Lycoming IO-540. The electrical design is my own with major influence from Bob Nuckols and this list. Thanks for that. She has two equal batteries (Odessy 925) and a single alternator (B&C 60 amp). One mag and one elec ign. DC1 is direct wired into the main bus. DC2 is direct wired into the Avionics/Essential bus. The battery contactors have separate pilot controlled on/off switches. They share a common hot bus bar thru separate schokey diodes. In normal ops I plan to have both battery contactors closed for start. Electrically the batt outputs will be isolated at this point. I have a 40 amp relay that is pilot controlled, to parallel the batteries after the engine is started. I have a Garmin 480 GPS/NAV and a TruTrak Digi II VSGV and a GRT EFIS Horizon I to protect from starting circuit voltage sags and surges. Here is my question. After start, when the engine is stable at idle power, I will close the alternator field. This action will cause the main bus (through a 60 amp current limiter) up to a nominal 14.2 volts. Then I plan to close a two way solid state "bus tie" relay which sits electrically between the two bus terminal blocks. This will bring the Avionics-Ess bus to the same 14.2 volts and will serve as my DC2 charge wire path. So is this 12 to 14.2 voltage boost going to hurt my avionics if they are already on? Should I leave them off until I have tied the system together? The amp loading on either bus as this point in the checklist is going to be minimal. Thanks, Terry Miles ________________________________ Message 9 _____________________________________ Time: 03:51:46 PM PST US Subject: Re: AeroElectric-List: Final Review From: "Matt Prather" Going from 12V to 14V absolutely won't hurt the avionics. It also doesn't sound to me like the operation should cause any significant inductive kick which would lead to a high power voltage excursion. Consider that with the bus loaded (at least on some systems), if the engine is brought to idle RPM, the bus voltage may sag significantly below 14V. Increasing the RPM or reducing the bus load will increase the voltage back to the regulator setup. DO160 (the standard to which Avionics manufacturers should design their products) allows for much larger swings than this.. Regards, Matt- > Bob, and all, > > I have just completed a Velocity. She just passed the FAA cert and, I am > going thru the process once more of looking at all of my work and > hopefully > asking all the right questions. > > I have built a Velocity XLRG. She has a 300 HP Lycoming IO-540. The > electrical design is my own with major influence from Bob Nuckols and this > list. Thanks for that. She has two equal batteries (Odessy 925) and a > single alternator (B&C 60 amp). One mag and one elec ign. > > DC1 is direct wired into the main bus. DC2 is direct wired into the > Avionics/Essential bus. The battery contactors have separate pilot > controlled on/off switches. They share a common hot bus bar thru separate > schokey diodes. In normal ops I plan to have both battery contactors > closed > for start. Electrically the batt outputs will be isolated at this point. > I > have a 40 amp relay that is pilot controlled, to parallel the batteries > after the engine is started. I have a Garmin 480 GPS/NAV and a TruTrak > Digi > II VSGV and a GRT EFIS Horizon I to protect from starting circuit voltage > sags and surges. > > Here is my question. > > After start, when the engine is stable at idle power, I will close the > alternator field. This action will cause the main bus (through a 60 amp > current limiter) up to a nominal 14.2 volts. Then I plan to close a two > way > solid state "bus tie" relay which sits electrically between the two bus > terminal blocks. This will bring the Avionics-Ess bus to the same 14.2 > volts and will serve as my DC2 charge wire path. > > So is this 12 to 14.2 voltage boost going to hurt my avionics if they are > already on? Should I leave them off until I have tied the system > together? > The amp loading on either bus as this point in the checklist is going to > be > minimal. > > Thanks, > Terry Miles > > ________________________________ Message 10 ____________________________________ Time: 04:59:06 PM PST US From: "Kenneth Melvin" Subject: RE: AeroElectric-List: 496 Audio Very useful information! I am currently wiring the 496 audio/warning output into the "music" jack of the PS4000 audio-panel. Does one tie the "voice+" and "warning" wires together into the "tip" terminal, and the "voice -" to the other? Thanks, Kenneth Melvin, Hillsboro, Oregon. ________________________________ Message 11 ____________________________________ Time: 05:24:44 PM PST US From: "Robert Feldtman" Subject: Re: AeroElectric-List: Final Review Simple question - why does anyone have their avionics "ON" when starting the engine, or the alternator for that matter - or when shutting down? Leave it all off til stable then turn on the avionics master. If you are worrying about unstable voltage with an air restart, you have bigger problems than whteher the EFIS comes back up quick (it does, seen the GRT do it in about 10 secs in a Cozy) bobf On 11/2/07, Terry Miles wrote: > > Bob, and all, > > > I have just completed a Velocity. She just passed the FAA cert and, I am going thru the process once more of looking at all of my work and hopefully asking all the right questions. > > > I have built a Velocity XLRG. She has a 300 HP Lycoming IO-540. The electrical design is my own with major influence from Bob Nuckols and this list. Thanks for that. She has two equal batteries (Odessy 925) and a single alternator (B&C 60 amp). One mag and one elec ign. > > > DC1 is direct wired into the main bus. DC2 is direct wired into the Avionics/Essential bus. The battery contactors have separate pilot controlled on/off switches. They share a common hot bus bar thru separate schokey diodes. In normal ops I plan to have both battery contactors closed for start. Electrically the batt outputs will be isolated at this point. I have a 40 amp relay that is pilot controlled, to parallel the batteries after the engine is started. I have a Garmin 480 GPS/NAV and a TruTrak Digi II VSGV and a GRT EFIS Horizon I to protect from starting circuit voltage sags and surges. > > > Here is my question. > > > After start, when the engine is stable at idle power, I will close the alternator field. This action will cause the main bus (through a 60 amp current limiter) up to a nominal 14.2 volts. Then I plan to close a two way solid state "bus tie" relay which sits electrically between the two bus terminal blocks. This will bring the Avionics-Ess bus to the same 14.2 volts and will serve as my DC2 charge wire path. > > > So is this 12 to 14.2 voltage boost going to hurt my avionics if they are already on? Should I leave them off until I have tied the system together? The amp loading on either bus as this point in the checklist is going to be minimal. > > > Thanks, > > Terry Miles > > ________________________________ Message 12 ____________________________________ Time: 05:42:27 PM PST US From: Gilles Thesee Subject: Re: AeroElectric-List: Final Review Robert Feldtman a crit : > Simple question - why does anyone have their avionics "ON" when starting the > engine, or the alternator for that matter - or when shutting down? Robert, Some installation have an EFIS to monitor engine or system parameters : voltage, RPM, oil pressure, temperatures, etc... I would be reluctant to wait for the *voltage* to be stable before having any indication of revolutions or oil pressure at engine start. Switching everything down for starting or shutting the engine is an old habit from sooo long ago. > whteher the EFIS comes back up quick (it does, seen the GRT do it in about > 10 secs in a Cozy) > I've just spent two days flying an airplane with a moving map GPS. This poorly engineered device kept resetting any time the voltage was sagging, when maneuvering the flaps on the ground, for instance. A real nuisance. BTW, 10 seconds seems a bit long in flight. On the other hand the little Dynon, or the Enigma are rock stable whatever the usual voltage variation.... Correctly designed aviation electronic devices are impervious to ordinary voltage fluctuations. Best regards, -- Gilles http://contrails.free.fr ________________________________ Message 13 ____________________________________ Time: 06:01:04 PM PST US From: Dan Billingsley Subject: Re: AeroElectric-List: Re: WTB Crystal Radio Eric, Tom has some interesting stuff going on with his projects. Dan "Eric M. Jones" wrote: You guys...Darned I've spent half a day Googling Xtal sets. A MUST SEE: http://www.wynterarchtops.com/radios/index.htm I hate to see anyone build a crystal set and cheap-out by buying the variable capacitor. There's no magic in capacitors. A roll of foil and some scissors will make one in a pinch. There is a long history of capacitors in strange forms. And if it doesn't have a cat's whisker and a galena crystal....shame on you. One of my pet projects (after I finish the Glastar....) is to build crytal sets along the lines of a Captain Nemo fantasy. It is entirely possible to build a an AM radio receiver using nothing you couldn't buy in AD 1200. "Inventor: A person who makes an ingenious arrangement of wheels, levers and springs, and believes it civilization." --Ambrose Bierce -------- Eric M. Jones www.PerihelionDesign.com 113 Brentwood Drive Southbridge, MA 01550 (508) 764-2072 emjones@charter.net Read this topic online here: http://forums.matronics.com/viewtopic.php?p=143432#143432 ________________________________ Message 14 ____________________________________ Time: 06:33:14 PM PST US From: "Terry Watson" Subject: RE: AeroElectric-List: Final Review Gilles, Can you tell us the make and model of the flakey EFIS, and a little more about the circumstances? Terry -----Original Message----- From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Gilles Thesee Sent: Friday, November 02, 2007 5:42 PM Subject: Re: AeroElectric-List: Final Review I've just spent two days flying an airplane with a moving map GPS. This poorly engineered device kept resetting any time the voltage was sagging, when maneuvering the flaps on the ground, for instance. A real nuisance. BTW, 10 seconds seems a bit long in flight. On the other hand the little Dynon, or the Enigma are rock stable whatever the usual voltage variation.... Correctly designed aviation electronic devices are impervious to ordinary voltage fluctuations. Best regards, -- Gilles http://contrails.free.fr ________________________________ Message 15 ____________________________________ Time: 07:28:36 PM PST US From: "Terry Miles" Subject: RE: AeroElectric-List: Final Review Matt: Thanks for the input. I appreciate that. Bob: I have separate electrical power sources and bus isolation capability. I deliberately designed a system so I could possibly do GPS flight planning activity prior to engine start and not need to shut it all off just for engine starter loads.or monitoring ATC with gate holds. I didn't follow your comment on airstarts. In that event, with any prop rotation at all you don't need to engage the starter. Terry _____ From: owner-aeroelectric-list-server@matronics.com [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert Feldtman Sent: Friday, November 02, 2007 8:22 PM Subject: Re: AeroElectric-List: Final Review Simple question - why does anyone have their avionics "ON" when starting the engine, or the alternator for that matter - or when shutting down? Leave it all off til stable then turn on the avionics master. If you are worrying about unstable voltage with an air restart, you have bigger problems than whteher the EFIS comes back up quick (it does, seen the GRT do it in about 10 secs in a Cozy) bobf On 11/2/07, Terry Miles wrote: Bob, and all, I have just completed a Velocity. She just passed the FAA cert and, I am going thru the process once more of looking at all of my work and hopefully asking all the right questions. I have built a Velocity XLRG. She has a 300 HP Lycoming IO-540. The electrical design is my own with major influence from Bob Nuckols and this list. Thanks for that. She has two equal batteries (Odessy 925) and a single alternator (B&C 60 amp). One mag and one elec ign. DC1 is direct wired into the main bus. DC2 is direct wired into the Avionics/Essential bus. The battery contactors have separate pilot controlled on/off switches. They share a common hot bus bar thru separate schokey diodes. In normal ops I plan to have both battery contactors closed for start. Electrically the batt outputs will be isolated at this point. I have a 40 amp relay that is pilot controlled, to parallel the batteries after the engine is started. I have a Garmin 480 GPS/NAV and a TruTrak Digi II VSGV and a GRT EFIS Horizon I to protect from starting circuit voltage sags and surges. Here is my question. After start, when the engine is stable at idle power, I will close the alternator field. This action will cause the main bus (through a 60 amp current limiter) up to a nominal 14.2 volts. Then I plan to close a two way solid state "bus tie" relay which sits electrically between the two bus terminal blocks. This will bring the Avionics-Ess bus to the same 14.2 volts and will serve as my DC2 charge wire path. So is this 12 to 14.2 voltage boost going to hurt my avionics if they are already on? Should I leave them off until I have tied the system together? The amp loading on either bus as this point in the checklist is going to be minimal. Thanks, Terry Miles ------------------------------------------------------------------------------------- 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.