---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Tue 01/12/16: 22 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 06:41 AM - Re: Ground power supplies DIY (Robert L. Nuckolls, III) 2. 07:50 AM - Re: Ground power supplies DIY (Jeff) 3. 08:02 AM - Re: Ground power supplies DIY (user9253) 4. 09:46 AM - Schematic for twin PM alternators (Paul Eckenroth) 5. 09:48 AM - Re: Ground power supplies DIY (Robert L. Nuckolls, III) 6. 09:48 AM - Re: Ground power supplies DIY (Robert L. Nuckolls, III) 7. 09:53 AM - Re: Schematic for twin PM alternators (Robert L. Nuckolls, III) 8. 09:56 AM - Re: Ground power supplies DIY (Robert L. Nuckolls, III) 9. 09:58 AM - Re: Ground power supplies DIY (Daniel Hooper) 10. 10:22 AM - Re: Ground power supplies DIY (Bob McCallum) 11. 10:40 AM - Re: Schematic for twin PM alternators (Charlie England) 12. 10:42 AM - Re: Ground power supplies DIY (Eric Page) 13. 11:19 AM - Re: Step up/Down Voltage Regulator (H. Marvin Haught) 14. 12:03 PM - Re: Schematic for twin PM alternators (Paul Eckenroth) 15. 12:41 PM - Grounding Tabs (James Bean) 16. 01:42 PM - Re: Grounding Tabs (Michael Lazarowicz) 17. 02:13 PM - Re: Step up/Down Voltage Regulator (user9253) 18. 02:31 PM - Re: Grounding Tabs (Robert L. Nuckolls, III) 19. 03:00 PM - Re: Schematic for twin PM alternators (user9253) 20. 06:05 PM - Electrical system design critique (Jump4way) 21. 06:53 PM - Re: Schematic for twin PM alternators (Charlie England) 22. 09:07 PM - Re: Electrical system design critique (user9253) ________________________________ Message 1 _____________________________________ Time: 06:41:44 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Ground power supplies DIY At 08:04 PM 1/11/2016, you wrote: >So what's the difference of using one of these ? >http://www.amazon.com/Schumacher-SE-1275A-Automatic-Onboard-Battery/dp/B000BO8TTY > >I have one already could I just connect it to external power plug >and be good to go (the battery is still on line) is it not as clean >for power output ? (granted it's really only 12amps) Those do not deliver smooth DC voltage. They are CHARGERS . . . not POWER SUPPLIES. Bob . . . ________________________________ Message 2 _____________________________________ Time: 07:50:59 AM PST US From: Jeff Subject: Re: AeroElectric-List: Ground power supplies DIY Is that a YES or a NO, Bob? Doesn't a charger, in combination with a battery, deliver power that is clea n enough to do the job? Sent from my iPad > On Jan 12, 2016, at 06:36, Robert L. Nuckolls, III wrote: > > At 08:04 PM 1/11/2016, you wrote: >> So what=99s the difference of using one of these ? >> http://www.amazon.com/Schumacher-SE-1275A-Automatic-Onboard-Battery/dp/B0 00BO8TTY >> >> I have one already could I just connect it to external power plug and be g ood to go (the battery is still on line) is it not as clean for power output ? (granted it=99s really only 12amps) > > Those do not deliver smooth DC voltage. They are > CHARGERS . . . not POWER SUPPLIES. > > ========================== ========================== ========================== ========================== ========================== ========================== ====== ________________________________ Message 3 _____________________________________ Time: 08:02:37 AM PST US Subject: AeroElectric-List: Re: Ground power supplies DIY From: "user9253" I have an RV-12 E-LSA with a Odyssey PC680 battery. If I intend to sit on the ground with the Dynon D-180 turned on for more than 5 minutes, I will connect a battery/maintainer similar to this one: Walmart #: 001036720 It is a charger, not a power supply. But it has worked fine for me for the past 5 years. I have read that modern avionics should be capable of withstanding anything that an aircraft electrical system can throw at them. I suspect that the Schumacher charger will not put out as much noise and voltage spikes as an aircraft electrical system with relays, contactors, RF transmitters, motors, strobes, alternators, and etc. An avionics technician doing serious bench testing, will want a high quality power supply. But for a pilot sitting in the airplane pushing buttons to learn how to use a glass panel, I agree with Charlie's posts above. -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451905#451905 ________________________________ Message 4 _____________________________________ Time: 09:46:10 AM PST US Subject: AeroElectric-List: Schematic for twin PM alternators From: "Paul Eckenroth" I'm building a Onex that takes a VW engine. The engine is a Revmaster which has two 20 Amp PM generators housed in the accessory case. I believe the output for each would be single phase. I read that the PM alternators generate variable voltage based on RPM. I am hoping to use a Lithium battery which has a maximum charging voltage of 14.7V. Would like recommendations on how to create a reliable and safe combination of elements. I have built an RV9A using Aeroelectric guidelines for the electrical system and created a totally trouble free airplane. Hoping to do it again with the Onex but cannot find the relevant information. Need help. Paul Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451909#451909 ________________________________ Message 5 _____________________________________ Time: 09:48:39 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Ground power supplies DIY At 08:04 PM 1/11/2016, you wrote: >So what's the difference of using one of these ? >http://www.amazon.com/Schumacher-SE-1275A-Automatic-Onboard-Battery/dp/B000BO8TTY > >I have one already could I just connect it to external power plug >and be good to go (the battery is still on line) is it not as clean >for power output ? (granted it's really only 12amps) Those do not deliver smooth DC voltage. They are CHARGERS . . . not POWER SUPPLIES. Bob . . . ________________________________ Message 6 _____________________________________ Time: 09:48:39 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Ground power supplies DIY At 10:05 PM 1/11/2016, you wrote: >Power supplies have several different types of ratings, and most >have no overvoltage protection in case the power supply regulator fails. >One of the ratings is how much current (Amps) will it provide while >maintaining the rated voltage. >Ripple is a rating about how much the voltage is allowed to >fluctuate while providing current. The fluctuation is normally at >about 60 Hz (cycles per second) for older designs, however, the >modern switching type power supplies may have ripple at many >different frequencies that may or may not show up as a humming noise >on radios, etc. Here's my present value-choice for an AC mains ground power supply . . . http://tinyurl.com/zbn5g6m It comes with lots of approvals. There's no reason to suspect that the 'protective' features cited are not equal to the best we know how to do in that industry. . . . and it's tough to beat the price/performance numbers. This is on a part with a 20A switchmode supply I used to sell out of the 'Connection inventory about 10 years ago . . . but at 1/4th the price. Bob . . . ________________________________ Message 7 _____________________________________ Time: 09:53:54 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Schematic for twin PM alternators At 11:44 AM 1/12/2016, you wrote: > >I'm building a Onex that takes a VW engine. The engine is a >Revmaster which has two 20 Amp PM generators housed in the accessory >case. I believe the output for each would be single phase. I read >that the PM alternators generate variable voltage based on RPM. I >am hoping to use a Lithium battery which has a maximum charging >voltage of 14.7V. Would like recommendations on how to create a >reliable and safe combination of elements. I have built an RV9A >using Aeroelectric guidelines for the electrical system and created >a totally trouble free airplane. Hoping to do it again with the >Onex but cannot find the relevant information. Need help. How does Revmaster suggest that these alternators be used? Can you tell us where to download the relevant installation guidance? Bob . . . ________________________________ Message 8 _____________________________________ Time: 09:56:30 AM PST US From: "Robert L. Nuckolls, III" Subject: RE: AeroElectric-List: Ground power supplies DIY > . . . and it's tough to beat the price/performance > numbers. This is on a part with a 20A switchmode > supply I used to sell out of the 'Connection > inventory about 10 years ago . . . but at 1/4th > the price. Oh yeah, order the 15 volt version and adjust it down to 14v to run your airplane. Bob . . . ________________________________ Message 9 _____________________________________ Time: 09:58:28 AM PST US From: Daniel Hooper Subject: Re: AeroElectric-List: Ground power supplies DIY > > On Jan 12, 2016, at 11:47 AM, Robert L. Nuckolls, III wrote: > > Here's my present value-choice for an AC > mains ground power supply . . . So connecting this 15V supply through a silicon diode would put the output at around 14.4V.. is that the idea? Thanks, Daniel ________________________________ Message 10 ____________________________________ Time: 10:22:19 AM PST US From: Bob McCallum Subject: RE: AeroElectric-List: Ground power supplies DIY No. The output is adjustable. Simply turn the voltage adjustment slightly c ounterclockwise to achieve the desired output. Bob McC From: enginerdy@gmail.com Subject: Re: AeroElectric-List: Ground power supplies DIY On Jan 12=2C 2016=2C at 11:47 AM=2C Robert L. Nuckolls=2C III wrote: Here's my present value-choice for an AC mains ground power supply . . . So connecting this 15V supply through a silicon diode would put the output at around 14.4V.. is that the idea? Thanks=2CDaniel ________________________________ Message 11 ____________________________________ Time: 10:40:20 AM PST US Subject: Re: AeroElectric-List: Schematic for twin PM alternators From: Charlie England On 1/12/2016 11:44 AM, Paul Eckenroth wrote: > > I'm building a Onex that takes a VW engine. The engine is a Revmaster which has two 20 Amp PM generators housed in the accessory case. I believe the output for each would be single phase. I read that the PM alternators generate variable voltage based on RPM. I am hoping to use a Lithium battery which has a maximum charging voltage of 14.7V. Would like recommendations on how to create a reliable and safe combination of elements. I have built an RV9A using Aeroelectric guidelines for the electrical system and created a totally trouble free airplane. Hoping to do it again with the Onex but cannot find the relevant information. Need help. > > Paul Doesn't the Revmaster come with regulators for the PM generators? The output of the regulators should be more or less 'standard' a/c operating voltage of 14V. If you don't have regulators in the circuit, the battery will likely outlast your electronics. :-) Charlie ________________________________ Message 12 ____________________________________ Time: 10:42:38 AM PST US Subject: Re: AeroElectric-List: Ground power supplies DIY From: Eric Page On Jan 12, 2016, at 9:56 AM, Daniel Hooper wrote: > So connecting this 15V supply through a silicon diode would put the output at around 14.4V.. is that the idea? > > Thanks, > Daniel There's a potentiometer on the unit that allows output voltage adjustment within approximately +/-10% of nominal. The listing says the limits are 13.5V - 16.5V. Eric ________________________________ Message 13 ____________________________________ Time: 11:19:13 AM PST US From: "H. Marvin Haught" Subject: Re: AeroElectric-List: Step up/Down Voltage Regulator Don=99t want to hijack a thread, but last week, while visiting a local salvage sales company, was looking a table full of Simran SMVS-300 (300 Watts) Step-up/Down Voltage regulators with built in circuit breaker. These appear to be brand new. Was standing there trying to figure for what they would be used as I studied one, and the owner walked by and told me to take it home with me. So I did, but have no idea how it would be used? Photos attached. > On Jan 12, 2016, at 11:47 AM, Robert L. Nuckolls, III wrote: > > At 10:05 PM 1/11/2016, you wrote: >> Power supplies have several different types of ratings, and most have no overvoltage protection in case the power supply regulator fails. >> One of the ratings is how much current (Amps) will it provide while maintaining the rated voltage. >> Ripple is a rating about how much the voltage is allowed to fluctuate while providing current. The fluctuation is normally at about 60 Hz (cycles per second) for older designs, however, the modern switching type power supplies may have ripple at many different frequencies that may or may not show up as a humming noise on radios, etc. > > Here's my present value-choice for an AC > mains ground power supply . . . > > http://tinyurl.com/zbn5g6m > > It comes with lots of approvals. There's > no reason to suspect that the 'protective' > features cited are not equal to the best > we know how to do in that industry. > > . . . and it's tough to beat the price/performance > numbers. This is on a part with a 20A switchmode > supply I used to sell out of the 'Connection > inventory about 10 years ago . . . but at 1/4th > the price. > > > Bob . . . > ________________________________ Message 14 ____________________________________ Time: 12:03:53 PM PST US Subject: Re: AeroElectric-List: Schematic for twin PM alternators From: Paul Eckenroth The Revmaster comes with very basic installation instructions. They have a schematic showing the two output wires going to a rectifier/regulator TMG-3096 with a fuse on one leg of the output. I have been unable to find anything on this rectifier using Google. I am concerned about keeping the voltage within the requirements of the Lithium battery, any requirement for automatic shut down, connecting the two alternators to a single battery, etc. Paul On Tue, Jan 12, 2016 at 1:40 PM, Charlie England wrote: > ceengland7@gmail.com> > > On 1/12/2016 11:44 AM, Paul Eckenroth wrote: > >> jeckenroth@nbn.net> >> >> I'm building a Onex that takes a VW engine. The engine is a Revmaster >> which has two 20 Amp PM generators housed in the accessory case. I believe >> the output for each would be single phase. I read that the PM alternators >> generate variable voltage based on RPM. I am hoping to use a Lithium >> battery which has a maximum charging voltage of 14.7V. Would like >> recommendations on how to create a reliable and safe combination of >> elements. I have built an RV9A using Aeroelectric guidelines for the >> electrical system and created a totally trouble free airplane. Hoping to >> do it again with the Onex but cannot find the relevant information. Need >> help. >> >> Paul >> > Doesn't the Revmaster come with regulators for the PM generators? The > output of the regulators should be more or less 'standard' a/c operating > voltage of 14V. > > If you don't have regulators in the circuit, the battery will likely > outlast your electronics. :-) > > Charlie > > ________________________________ Message 15 ____________________________________ Time: 12:41:42 PM PST US From: James Bean Subject: AeroElectric-List: Grounding Tabs I don't see why you say it is not practical to mount on the firewall. My 8 has tabs on both sides of the firewall with a big brass bolt through the whole thing that picks up the engine ground strap. They are just below the baggage compartment floor. Worked for me. cheers Jim Bean Time: 12:36:37 PM PST US Subject: Re: Returned Mail: Re: Grounding Tabs From: Michael Lazarowicz Thanks Bob. I will use the Forest of Tabs. Like I said in previous post. It is not Practical in the RV 8 to locate the forest on the firewall so it will be mounted on the bulkhead behind the panel ( Isolated from that thin bulkhead and I will ground everything I can to those tabs. I will use a #6 wire to connect that to the firewall/batter/engine strap bolt. I guess my confusion is Z-15 Shows all " panel grounds " in one place and all firewall grounds in another. I just wondered if by sharing that #6 wire to the firewall I would cause a problem? Thanks for your patience On Sun, Jan 10, 2016 at 6:55 PM, Robert L. Nuckolls, III < nuckolls.bob@aeroelectric.com> wrote: > At 04:35 PM 1/10/2016, you wrote: > > I have read Bob's reply.=C3=82 It raises another question.=C3=82 If I w ere to use > B&C forest of tabs to ground everything.=C3=82 Flap motor , P. Heat,=C3 =82 strobes, > interior lights and all the panel stuff like coms, audio panel etc.=C3=82 would > that cause a ground loop. > > > No . . . the "ideal" single point ground philosophy > says take EVERYTHING to one place . . . except for > the simplest of small airplanes, this is impractical. > > As shown in the Z-15 figures, collect all panel grounds > (potential victims) to one place, all airframe grounds > to firewall as practical . . . or ground locally as > convenience dictates. > > For plastic airplanes, then -A- you DO gather airframe grounds to > the firewall and -B- take an extension wire from > the panel ground down to the firewall. > > Bob . . . > ________________________________ Message 16 ____________________________________ Time: 01:42:36 PM PST US Subject: Re: AeroElectric-List: Grounding Tabs From: Michael Lazarowicz James , You are correct. it is not impractical to mount the tabs there. It is purely a mater of style and preference. I just did not want to run 20+ panel wires there. I actually got the Idea from one of Stein Airs Avionics guys who built an beautiful 8 that won a Lindy last summer at Oshkosh. He put a small forest of Tabs on the bulkhead behind the panel and it made for real simple panel grounding locations. In his case, he just connected the forest to a piece of structure and did not go all the way to the firewall. He also had a rear mounted battery, mine is up front I really like the forest of tabs on the firewall. It makes so much sense. Where I became confused ( and still am) is when Bob . proposed using a remote connection from that ground to all the panel stuff. My logic was if you are going to move the panel grounds, why not all of them. It appears now , after reading Bob's book more closely that there is some advantage to not having one central point for everything. This whole electrical thing for me is not just about building, but an education in this stuff I have never had. I am grateful to Bob and all who take the time to answer my questions. Mike On Tue, Jan 12, 2016 at 3:36 PM, James Bean wrote: > > I don't see why you say it is not practical to mount on the firewall. > My 8 has tabs on both sides of the firewall with a big brass bolt through > the whole thing that picks > up the engine ground strap. They are just below the baggage compartment > floor. > Worked for me. > cheers Jim Bean > > Time: 12:36:37 PM PST US > Subject: Re: Returned Mail: Re: Grounding Tabs > From: Michael Lazarowicz > > Thanks Bob. I will use the Forest of Tabs. Like I said in previous > post. > It is not Practical in the RV 8 to locate the forest on the firewall > so it > will be mounted on the bulkhead behind the panel ( Isolated from > that thin > bulkhead and I will ground everything I can to those tabs. I will > use a #6 > wire to connect that to the firewall/batter/engine strap bolt. I > guess my > confusion is Z-15 Shows all " panel grounds " in one place and all > firewall grounds in another. I just wondered if by sharing that #6 > wire to > the firewall I would cause a problem? > > Thanks for your patience > > On Sun, Jan 10, 2016 at 6:55 PM, Robert L. Nuckolls, III < > nuckolls.bob@aeroelectric.com> wrote: > > > At 04:35 PM 1/10/2016, you wrote: > > > > I have read Bob's reply.=C3=82 It raises another question.=C3=82 > If I w > ere to use > > B&C forest of tabs to ground everything.=C3=82 Flap motor , P. > Heat,=C3 > =82 strobes, > > interior lights and all the panel stuff like coms, audio panel > etc.=C3=82 > would > > that cause a ground loop. > > > > > > No . . . the "ideal" single point ground philosophy > > says take EVERYTHING to one place . . . except for > > the simplest of small airplanes, this is impractical. > > > > As shown in the Z-15 figures, collect all panel grounds > > (potential victims) to one place, all airframe grounds > > to firewall as practical . . . or ground locally as > > convenience dictates. > > > > For plastic airplanes, then -A- you DO gather airframe grounds to > > the firewall and -B- take an extension wire from > > the panel ground down to the firewall. > > > > Bob . . . > > > > ________________________________ Message 17 ____________________________________ Time: 02:13:29 PM PST US Subject: AeroElectric-List: Re: Step up/Down Voltage Regulator From: "user9253" It looks like it will convert 240 VAC to 120 VAC or vice-versa. The ad mentions a refrigerator, but 300 watts will not handle that. http://www.220converters.com/store/p/69-Simran-SMVS300-300-W-Watts-Voltage-Converter-with-Stabilizer.html -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451930#451930 ________________________________ Message 18 ____________________________________ Time: 02:31:21 PM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: Grounding Tabs At 02:36 PM 1/12/2016, you wrote: > >I don't see why you say it is not practical to mount on the firewall. . . . if you've got something like a Kitfox with a few day/vfr avionics and the panel hardware is close to the firewall ground . . . then it's easy. But if you have a LAIVP with a panel full of electron herders and byte thrashers, it's not so practical to run a BUNDLE of shield, audio, power and signal grounds up to the firewall. Then it makes more sense to gather all those things up AT THE PANEL then, if a plastic airplane, EXTEND the panel ground to the firewall on a suitable conductor. If a metal airplane, then no extension is necessary or helpful. Bob . . . ________________________________ Message 19 ____________________________________ Time: 03:00:40 PM PST US Subject: AeroElectric-List: Re: Schematic for twin PM alternators From: "user9253" How many wires come from the alternator, just two or two pairs? Are the wires marked or color coded? Do you have a picture of the rectifier/regulator? Can you post the schematic that you have? -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451935#451935 ________________________________ Message 20 ____________________________________ Time: 06:05:22 PM PST US Subject: AeroElectric-List: Electrical system design critique From: "Jump4way" I'm working on my electrical system design. My plan is to install the EFII system using two alternators and one battery. The primary ECU, injector, fuel pump, and ignition will be powered off the always hot battery bus with the secondary set of the above powered off of the main bus. I've chosen to install a couple of fusible links in areas where the aeroelectric connection book recommends wire runs 6" or less and I was unable to achieve that. I'm not sure if a run of 2-3 ft would require a fusible link... still scratching my head on that. I haven't completed the diagram quite yet as I haven't decided on which alternator/regulator combo to go with so that portion is left mostly out at this point. Avionics haven't been purchased yet but I'm leaning towards the Garmin G3x suite of instruments. Any feedback would be very appreciated. I apologize for the quality of the drawing. Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451938#451938 Attachments: http://forums.matronics.com//files/z1320_efii_584.png ________________________________ Message 21 ____________________________________ Time: 06:53:41 PM PST US Subject: Re: AeroElectric-List: Schematic for twin PM alternators From: Charlie England I don't have direct knowledge of the Revmaster stuff, but it's highly likely that it functions just like any other 'dynamo'. Basically, you hook up the 'rectifier' as recommended, and variable frequency, variable voltage goes in and regulated 14.x volts DC comes out. It's not likely that there's any overvoltage protection built in, so that would need to be done with an external device(s). IIRC, there's info in the Connection on how to handle dynamo style alternator/regulator systems. An overvoltage detection module that drives a relay (contactor) capable of handling the regulators max output is the simplest way to protect from an overvoltage event. If there are two separate dynamos, you'd need two separate protection systems. Charlie On 1/12/2016 2:00 PM, Paul Eckenroth wrote: > The Revmaster comes with very basic installation instructions. They > have a schematic showing the two output wires going to a > rectifier/regulator TMG-3096 with a fuse on one leg of the output. I > have been unable to find anything on this rectifier using Google. I > am concerned about keeping the voltage within the requirements of the > Lithium battery, any requirement for automatic shut down, connecting > the two alternators to a single battery, etc. > > Paul > > On Tue, Jan 12, 2016 at 1:40 PM, Charlie England > wrote: > > > > > On 1/12/2016 11:44 AM, Paul Eckenroth wrote: > > > > > I'm building a Onex that takes a VW engine. The engine is a > Revmaster which has two 20 Amp PM generators housed in the > accessory case. I believe the output for each would be single > phase. I read that the PM alternators generate variable > voltage based on RPM. I am hoping to use a Lithium battery > which has a maximum charging voltage of 14.7V. Would like > recommendations on how to create a reliable and safe > combination of elements. I have built an RV9A using > Aeroelectric guidelines for the electrical system and created > a totally trouble free airplane. Hoping to do it again with > the Onex but cannot find the relevant information. Need help. > > Paul > > Doesn't the Revmaster come with regulators for the PM generators? > The output of the regulators should be more or less 'standard' a/c > operating voltage of 14V. > > If you don't have regulators in the circuit, the battery will > likely outlast your electronics. :-) > > Charlie > > > ========== > br> fts!) > r> > href="http://www.buildersbooks.com" rel="noreferrer" > target="_blank">www.buildersbooks.com > rel="noreferrer" target="_blank">http://www.matronics.com/contribution > -Matt Dralle, List Admin. > ========== > - > Electric-List" rel="noreferrer" > target="_blank">http://www.matronics.com/Navigator?AeroElectric-List > ========== > FORUMS - > eferrer" target="_blank">http://forums.matronics.com > ========== > b Site - > -Matt Dralle, List Admin. > rel="noreferrer" target="_blank">http://www.matronics.com/contribution > ========== > > ________________________________ Message 22 ____________________________________ Time: 09:07:40 PM PST US Subject: AeroElectric-List: Re: Electrical system design critique From: "user9253" Does the solid state battery contactor conduct in BOTH directions? Is it rated for starter current? The 60 amp alternator needs a fuse located close to the contactors. If the 5 amp alternator field wire shorts out, the 15 amp fuse will likely blow before the circuit breaker trips. I recommend not putting two circuit protection devices in series. A separate avionics bus is not necessary and introduces unnecessary failure points. Read this thread: http://forums.matronics.com/viewtopic.php?t=16757246&sid=74d855944e77ced507a5bb87d7f9a72f and this document: http://www.aeroelectric.com/articles/avmaster.pdf -------- Joe Gores Read this topic online here: http://forums.matronics.com/viewtopic.php?p=451940#451940 ------------------------------------------------------------------------------------- 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.