AeroElectric-List Digest Archive

Fri 09/09/05


Total Messages Posted: 19



Today's Message Index:
----------------------
 
     1. 01:08 AM - 24 (28) vs 12 (14) volt systems (Wes Knettle)
     2. 06:03 AM - Re: Use a 28vdc alternator in 14vdc system? (Frank Stringham)
     3. 07:10 AM - Re: Use a 28vdc alternator in 14vdc system? (Craig Berland)
     4. 07:43 AM - Re: Use a 28vdc alternator in 14vdc system? (Robert L. Nuckolls, III)
     5. 07:52 AM - Re: 42 vs 24 vs 12 volt systems (Eric M. Jones)
     6. 08:57 AM - Re: Use a 28vdc alternator in 14vdc system? (Robert L. Nuckolls, III)
     7. 09:03 AM - Re: Re: 42 vs 24 vs 12 volt systems (Paul McAllister)
     8. 09:33 AM - Re: Use a 28vdc alternator in 14vdc system? (Robert L. Nuckolls, III)
     9. 10:26 AM - Re: mini jack source (Robert Dickson)
    10. 10:39 AM - Re: mini jack source (Robert L. Nuckolls, III)
    11. 10:56 AM - Re: Use a 28vdc alternator in 14vdc system? (Mickey Coggins)
    12. 11:25 AM - Re: mini jack source (Jim Baker)
    13. 11:41 AM - Re: Strobe noise on Piper Archer II (Mickey Coggins)
    14. 02:13 PM - Re: mini jack source (Robert Dickson)
    15. 02:13 PM - Re: Use a 28vdc alternator in 14vdc system? (PWilson)
    16. 06:58 PM - Re: Use a 28vdc alternator in 14vdc system? (Ken)
    17. 07:18 PM - DC to DC converter ()
    18. 09:03 PM - Re: mini jack source (Robert L. Nuckolls, III)
    19. 09:08 PM - Re: mini jack source (Mike)
 
 
 


Message 1


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    Time: 01:08:15 AM PST US
    From: Wes Knettle <wsknettl@centurytel.net>
    Subject: 24 (28) vs 12 (14) volt systems
    2.60 SUBJ_PAREN_NUMS Subject has several parenthesized numbers --> AeroElectric-List message posted by: Wes Knettle <wsknettl@centurytel.net> I'm going to try to answer a question with a question. Cessna 185's made the switch from 12 volt (G35 battery) to 24 volt (G242 battery) in the 70's. Otherwise the aircraft are the same with the same IO-520-D engine. I have maintained these 185's for 20 years. A hot start on a 12 volt 185 is a lot slower than a hot start on a 24 volt 185. I have seen this also on the Lycoming powered equipment. As for the evolution of DC mobile electrical systems it seems to me the goal has always been more cranking power and less weight. 6 volt cars crank slower than 12 volt cars and 12 volt cars crank slower than 24 volt cars. I have proven this over and over again with the Willys L134 engined jeeps which from 1941 thru 1971 came with 6, 12 and 24 volt systems. The weight savings comes in the form of lighter gage wire for the higher voltages and lighter weight motors and generators for higher voltages. It is now rumored that the auto industry is heading towards a 42 volt system. If cost savings by using 12 volt auto electrical parts is the only basis for selecting 12 volt for your project then by all means do so but there must be adequate improvements in performance to justify the 24 volt systems where cost is not the only consideration? As for sources of parts remember the military equipment standard has been 24 volts since 1950. There are tons of surplus military 24 volt electrical out there and it's cheap. Wes K > >


    Message 2


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    Time: 06:03:24 AM PST US
    From: "Frank Stringham" <fstringham@hotmail.com>
    Subject: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: "Frank Stringham" <fstringham@hotmail.com> Bruce Probably another reason I will not buy a span can cessna............... Frank @ SGU and SLC and also remember good friends dont't let their friends fly plastic planes!!!Sorry I just couldn't resist!!!!!!!!!!!!!!!!!! >From: "Bruce Gray" <Bruce@glasair.org> >Reply-To: aeroelectric-list@matronics.com >To: <aeroelectric-list@matronics.com> >Subject: RE: AeroElectric-List: Use a 28vdc alternator in 14vdc system? >Date: Thu, 8 Sep 2005 22:56:40 -0400 > >--> AeroElectric-List message posted by: "Bruce Gray" <Bruce@glasair.org> > >How many 14v airplanes does RAC or Cessna make today? Zip..Nada..Zero > >Bruce >www.glasair.org > > >-----Original Message----- >From: owner-aeroelectric-list-server@matronics.com >[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Robert >L. >Nuckolls, III >To: aeroelectric-list@matronics.com >Subject: RE: AeroElectric-List: Use a 28vdc alternator in 14vdc system? > > >--> AeroElectric-List message posted by: "Robert L. Nuckolls, III" ><nuckollsr@cox.net> > >At 05:52 PM 9/8/2005 -0400, you wrote: > > >--> AeroElectric-List message posted by: "Bruce Gray" <Bruce@glasair.org> > > > >28v is used in the trucking industry also. Nothing wrong with 14v, I just > >like more power and I don't like my panel to go dim at night when I lower > >the gear. > > More power to do what? The only 24 volt system I helpped > put in a long-ez was about 20 years ago when the builder > wanted electric heat in the cabin. We put a 24-volt > 100A system in and he still didn't have all the heat he > needed. > > A 14v, 60A system is good for 650W with charging reserves. > How much do you need that cannot be met with this source? > Dimming of the panel lights can be offset with REGULATING > dimmers like the ones we used to sell and now sold by > B&C. > > Bob . . . > >


    Message 3


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    Time: 07:10:51 AM PST US
    From: "Craig Berland" <cberland@systems3.net>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: "Craig Berland" <cberland@systems3.net> > >--> AeroElectric-List message posted by: "Bruce Gray" <Bruce@glasair.org> > > > >How many 14v airplanes does RAC or Cessna make today? Zip..Nada..Zero > > > >Bruce > > And just why do you suppose that is? > > Bob . . . > The reason is they are lighter and cheaper, but you knew that. General Motors engineers have wanted a 50 or 60 volt system for years, but that is a lot of momentum to change. I have 24v and 100amp to run an EEDS de-ice system and a hot prop on my IV-P. Craig Berland


    Message 4


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    Time: 07:43:45 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 12:49 AM 9/9/2005 -0400, you wrote: >--> AeroElectric-List message posted by: "Bruce Gray" <Bruce@glasair.org> > >Oh, the usual - commonality across production lines. You got it! >And it's better. (grin) There IS a physics component to the decision too . . . the capabilities of starters (1940's technology) and batteries (1900's technology) of the time were such that total loop resistance (losses) were less significant for a 24v system. With the much more capable lightweight starters (1980's) and recombinant gas batteries (1980's) it's easy to drive effects of loop resistance down to the same levels that 24v systems enjoyed 40 years ago. The major reason Cessna went all-28 was to use one alternator, one regulator and only two different batteries across an entire product line. Hence, even the lowly C-150 "enjoyed" superior cranking performance compared to any other airplane in the product line. How about cost-of-ownership? Cessna and contemporaries had very little control over cost of ownership decisions due to a then restrictive (and today oppressive) regulatory environment. Ford can make a $2 change to a car to reduce cost of ownership and recoup that $2 in very tiny increments over millions of cars. I'm working a change to a 20 year old design on a bizjet where a part has gone obsolete (the only thing that FORCES change) on an assembly with a bill of materials of under $100. The new part is form-fit-function replacement and has nothing to do with flight safety. None the less, after all the no-value-added hoops are jumped, all the reports are written and blessed, my company will have spent about $100,000 on a change that doesn't even improve the cost of ownership for that airplane . . . it only just preserves the decades old status of the system. The part will be built outside and probably cost my company $1000. It will fall into an ISO, FAA, FTC, EPA, OSHA, AFLCIO, IRS, etc. approved distribution system and go onto the customer's airplane for about $2,000 to $2,500. These same conditions prevail on virtually all certified aircraft. One would like to believe that everything we've seen roll of the assembly lines of these factories is based on good science, well considered economics, service to the customer and a controlling desire to improve customer perceptions of value. Nothing could be further from the truth. Some really big buzz programs circulating around the industry intended to improve on perceptions of value are considering things like high-speed Internet in the cabin, massage seats, heated seats, neat passenger operated electro-whizzies for the entertainment systems, etc. In the mean time, that $100 obsolete part problem along with all it's lesser and greater cousins are eating our collective lunch (supplier and customer). The only folks making out like bandits are those who receive salaries to make life miserable for those who produce and add value while adding no value of their own (and taking no responsibility for the current state of affairs). There is a grain of truth to many of the things we've come to believe about aviation's design and marketing decisions. I can tell you first hand that MOST of those decisions are NOT based in good engineering or science nor are they permitted to evolve with the new technologies. There were some demonstrated advantages of moving to 24 volt for some airplanes to offset starting problems. Most if not all of those reasons have evaporated under the influence of modern components. This opens the door for very cost effective designs for OBAM aircraft based largely on components and lessons learned in the automotive and consumer electronics industries who have to had perceptions of real value to their products or die. Certified aviation lives in a bubble of artificial life support. The 42v car is an interesting dream. It's not going to be easy. As the layers of the onion are peeled back and underlying simple-ideas are exposed, there are plenty of unanticipated dragons to slay. But know that the reason for the higher voltage is only mildly influenced by a desire for lighter wire bundles. The major drive is to produce more POWER for what is anticipated to be an increasingly power hungry set of systems. It's unlikely that many of these systems will find desire or favor with the OBAM aircraft community but who knows? Things have changed greatly in the last 20 years, we can only expect still greater changes in the next 20 years. Those changes will show up in airplanes for new kids on the block (Honda, Eclipse, Quest, et. als.) Given present circumstances, it's doubtful as to how much of it will show up on BePiCesMo products. Bob . . .


    Message 5


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    Time: 07:52:45 AM PST US
    From: "Eric M. Jones" <emjones@charter.net>
    Subject: Re: 42 vs 24 vs 12 volt systems
    --> AeroElectric-List message posted by: "Eric M. Jones" <emjones@charter.net> I remember when cars went from 6V to 12V. As I remember the chief issue was contacts and connections. I also remember when microprocessors went from 5V to 3V. But real airplanes and real men use three-phase 115VAC 400Hz. It should be possible to write a mountain of data into a spreadsheet and derive the lowest cost, lowest weight, most reliable system, but I am certain those three characteristics would conflict. Bob's point about the relative costs of automotive components is good advice. If you went to buy your electrical system from the 28V-Store, you'd find that most of the stuff was expensive, certificated (remember that they certify the milk, but they certificate the cow) and the selection would not be all that large. The 14V-Store has all the bargains and selection to be sure. Is the auto industry going to 42V? I was spreading that rumor too. More recent rumors show advantages to staying at 14V; because LED lighting systems, microprocessors, and mosfets solid-state switches, are more efficient and reliable at lower voltages, while the use of single-wire power busses makes the argument about smaller wire gauges less important. The integration of the starter and alternator works fine at 14V too. The extinguishing of electrical contact arcs is a difficult problem at 42V too. In short, the advantages of 28V don't seem to warrant the increased expense. I dream of the three-phase 115VAC 400Hz system with distributed down converters and motors the size of your pinky, four tiny wires snaking through the airplane driving beams of light piercing the darkness....then I wake up. Regards, Eric M. Jones (14VDC Glastar 5540 N5EJ still a-building) www.PerihelionDesign.com 113 Brentwood Drive Southbridge MA 01550-2705 (508) 764-2072 "The problem with the world is that only the intelligent people want to be smarter, and only the good people want to improve." - E Stobblehouse


    Message 6


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    Time: 08:57:21 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 07:06 AM 9/9/2005 -0700, you wrote: >--> AeroElectric-List message posted by: "Craig Berland" ><cberland@systems3.net> > > > > >--> AeroElectric-List message posted by: "Bruce Gray" <Bruce@glasair.org> > > > > > >How many 14v airplanes does RAC or Cessna make today? Zip..Nada..Zero > > > > > >Bruce > > > > And just why do you suppose that is? > > > > Bob . . . > > >The reason is they are lighter and cheaper, but you knew that. The delta-cost of components is trivial. Further, overall weight differences are quite small; the great weight savings for raising system voltage in small aircraft simply didn't materialize . . . although there are many vocal purveyors of the weight savings myth (who are unable to support it with fact). See: page 6-12 of http://www.aeroelectric.com/articles/richter/response_1.pdf and pages 5-6 of http://www.aeroelectric.com/articles/richter/response_2.pdf >General Motors engineers have wanted a 50 or 60 volt system for years, >but that is a lot of momentum to change. I have 24v and 100amp to run an >EEDS de-ice >system and a hot prop on my IV-P. EXACTLY! You have a driving need for 28v system NOT for lighter wire, NOT for better cranking but for POWER. You're running a lot of electric heat and accessories with some extraordinary demands. Do you have an air-conditioner too? The builder needs to look at a 60A, 14v alternator (840 watts) and decide what system requirements may require continuous loads that exceed about 75% of that value (25% headroom for battery charging). So, if 630 watts is not enough to run things, then one should consider whether or not a 100A alternator will suffice or is it better to go 28V at 60A (1680 watts) or even the system you've installed (2400 watts). Every change has trade-offs. Excursions out of the 14v world pushes you out of automotive technologies and toward aircraft technologies (artificially inflated costs). In your case, the tradeoffs were acceptable and necessary to meed your overall energy requirements set by rational design goals. Your airplane is representative of perhaps 1 to 2% of the OBAM aircraft fleet. For 98% of the builders to get wrapped around the 14/28 axle is (in my never humble opinion) a waste of time and sometimes emotional resources. Bob . . .


    Message 7


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    Time: 09:03:32 AM PST US
    From: "Paul McAllister" <paul.mcallister@qia.net>
    Subject: Re: 42 vs 24 vs 12 volt systems
    --> AeroElectric-List message posted by: "Paul McAllister" <paul.mcallister@qia.net> Hi all, I often read about some of the power requirements folks are demanding for there aircraft and wonder why. For each 746 watts of energy we consume means one horsepower less that drives the propellor. It is possible to build very economical systems (from a power consumption perspective) by using various components such as semi conductor contactors, LED lighting, pitot heat systems as described by Eric and so on. With some careful thought I was able to build a system that has an in flight consumption of 8.6 amps at 13.8 volts...... the need for a 28 volt system escapes me. Paul


    Message 8


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    Time: 09:33:40 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 09:55 PM 9/8/2005 -0400, you wrote: >--> AeroElectric-List message posted by: PJ Seipel <seipel@seznam.cz> > >Sure, but how much automotive stuff are you planning on using? Most >modern avionics take anything between 10 and 30 volts. 28v halogen >bulbs don't cost any more than the 12v version although they're less >common. Battery chargers are out there, try Concord. This isn't about our ability to craft any system of any voltage and do it well based on our understanding of the simple-ideas and costs (tradeoffs) of implementing combinations of simple-ideas . . . >I'm curious, does anyone have any reason why 28v is not a good idea >besides you can't use 12v automotive parts? That's the only reason I've >ever heard as to why people prefer 12v. I wouldn't call it a "bad" idea . . . just not necessary in terms of power requirements for the vast majority of OBAM aircraft and certainly not justified in terms of weights. To be sure, "justification" is subjective. I had a builder write me a few years ago and listed in detail the differences between a 14 and 28 volt system to meet his design goals. A high priority goal was weight and yes, he did document a savings of about 2 pounds. Assuming his calculations were correct, he was pleased with both the weight savings -AND- and costs to enjoy those savings. The decision is a GOOD one only if the individual making the decision sets the goals and then understands and accepts the tradeoffs to meet those goals. Folks have misunderstood my down-side comments about 28v as a goal to discourage use of the higher voltage. I wouldn't try to discourage anyone of meeting well considered design goals and acceptance of the costs based on understanding. Bob . . .


    Message 9


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    Time: 10:26:32 AM PST US
    From: Robert Dickson <robert@thenews-journal.com>
    Subject: Re: mini jack source
    --> AeroElectric-List message posted by: Robert Dickson <robert@thenews-journal.com> this is a good and obvious test, one I should of thought of myself. I just performed this test and, sure enough, the strobe noise went away when the jack was out of the panel. So, I'm back to my original question which is how to elegantly isolate this jack from my panel. Since I have a hole already drilled right where I'd like the jack I'd really like a jack with isolating washers just like my headset jacks, if such a creature exists. Robert Dickson RV-6A On Sep 8, 2005, at 8:35 PM, N1deltawhiskey@aol.com wrote: --> AeroElectric-List message posted by: N1deltawhiskey@aol.com In a message dated 08-Sep-05 16:26:25 Pacific Standard Time, robert@thenews-journal.com writes: Or, is there another way to skin this cat that won't look too junky in my nice clean panel? Robert, Have you tried duplicating the circumstances with the jack dismounted from the panel? Does it cure the problem? If not, I would be skeptical that simply isolating it from the panel will be the solution. Doug Windhorn


    Message 10


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    Time: 10:39:12 AM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: mini jack source
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 01:24 PM 9/9/2005 -0400, you wrote: >--> AeroElectric-List message posted by: Robert Dickson ><robert@thenews-journal.com> > >this is a good and obvious test, one I should of thought of myself. > >I just performed this test and, sure enough, the strobe noise went away >when the jack was out of the panel. Beware the evil ground loop! >So, I'm back to my original question which is how to elegantly isolate >this jack from my panel. Since I have a hole already drilled right >where I'd like the jack I'd really like a jack with isolating washers >just like my headset jacks, if such a creature exists. Got access to a lathe? You can cut some washers out of a good machinable plastic stock . . . Like Delrin. You might also consider labeling your jack with a rectangular engraved plastic placard like name plates are made from. You can oversize the hole behind the placard to clear the jack and allow the jack to be supported by the placard and provide insulation as well. There are some nice double-sided-sticky tapes to mount the placard. How thick is your panel and how much thicker could it be and still allow the jack to be installed with it's existing bushing length? Bob . . .


    Message 11


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    Time: 10:56:51 AM PST US
    From: Mickey Coggins <mick-matronics@rv8.ch>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch> > The builder needs to look at a 60A, 14v alternator (840 watts) > ... Are most alternator current specifications given assuming 14v? I'm planning on using this one: http://www.ecae.com/alt1.html 2025 Ultra Mini Alternator The text says this: East Coast Auto Electric UltraMini 12 Volt Series MINI-ALTERNATOR The UltraMini Alternator is the smallest in our line. It weights only 6 Lbs. and has an output of 55 amps. Is there a way I can find out if the 55 amps number is assuming 12v or 14v? Thanks, Mickey -- Mickey Coggins http://www.rv8.ch/ #82007 finishing do not archive


    Message 12


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    Time: 11:25:27 AM PST US
    From: "Jim Baker" <jlbaker@telepath.com>
    Subject: Re: mini jack source
    --> AeroElectric-List message posted by: "Jim Baker" <jlbaker@telepath.com> > I just performed this test and, sure enough, the strobe noise went > away when the jack was out of the panel. > > So, I'm back to my original question which is how to elegantly isolate > this jack from my panel. Look for a company called Small Parts Inc. online. Search for shoulder washer...made of nylon. For those interested in unique small parts, get their free catalog. Jim Baker 580.788.2779 '71 SV, 492TC Elmore City, OK


    Message 13


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    Time: 11:41:10 AM PST US
    From: Mickey Coggins <mick-matronics@rv8.ch>
    Subject: Re: Strobe noise on Piper Archer II
    --> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch> >>I'm getting a lot of strobe noise - ... > > First, try running the strobes from a pair of 6v > lantern batteries hooked in series or perhaps a small > motorcycle or garden tractor battery. If you're > working with an avionics shop, perhaps they have > a small bench supply you can used to power the strobes. > Hook the supply in right at the strobe supply and see > if the noise goes away. > > If it does, this confirms that the noise is being > conducted out of the strobe supply on the +14v > line. > > Try a fat electrolytic right across the +14v input > terminals to the strobes. Radio Shack has a 1000uF/ > 35v part 272-1019 that seems to come two in a package > for $1.69. > > If these have a very marked effect, it may mean that > capacitors normally occupying this same position INSIDE > the supply have gone bad. You have an option of adding > new caps outside or fixing the supply . . . how old is > it? > > If this has some effect but not enough, you may need to > add some inductance between the supply and the filter > caps. Review > > http://aeroelectric.com/articles/filter/RS_Noise_Filters.pdf > > for COTS filters that have been useful in curing this > noise in the past. I'm told that RS no longer carries > these filters so you may have to fabricate with discrete > capacitors and inductor. Jameco.com has suitable inductors. > For a strobe supply I'd try their p/n 2320-H > > Bob . . . > Thanks, guys, for the hints on how to solve this problem. Debugging will start tomorrow, hopefully. -- Mickey Coggins http://www.rv8.ch/ #82007 finishing do not archive


    Message 14


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    Time: 02:13:56 PM PST US
    From: Robert Dickson <robert@thenews-journal.com>
    Subject: Re: mini jack source
    --> AeroElectric-List message posted by: Robert Dickson <robert@thenews-journal.com> Bob the placard is actually a good idea, I think. I'm using a custom made placard for my switch row which is based closely on your switch clusters. It's not even glued on, just held in place by the switch nuts. If you give a decent trophy shop a vector file they can cut almost anything you want *exactly* where you want it. I get compliments on my switch labels, thanks to you. The darned jack just isn't long enough to clear anything but the .063 panel and still get the nut on. I'm not even using a washer. The placard material is generally even thicker than .063 (I think) so while it would isolate the jack I'd probably still have a problem mounting it. There must a jack out there some place that has a longer length. I'll keep looking. At least this is just a problem with the entertainment system! Thanks for your help. Robert Dickson Rv-6A On Sep 9, 2005, at 1:38 PM, Robert L. Nuckolls, III wrote: --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 01:24 PM 9/9/2005 -0400, you wrote: > --> AeroElectric-List message posted by: Robert Dickson > <robert@thenews-journal.com> > > this is a good and obvious test, one I should of thought of myself. > > I just performed this test and, sure enough, the strobe noise went away > when the jack was out of the panel. Beware the evil ground loop! > So, I'm back to my original question which is how to elegantly isolate > this jack from my panel. Since I have a hole already drilled right > where I'd like the jack I'd really like a jack with isolating washers > just like my headset jacks, if such a creature exists. Got access to a lathe? You can cut some washers out of a good machinable plastic stock . . . Like Delrin. You might also consider labeling your jack with a rectangular engraved plastic placard like name plates are made from. You can oversize the hole behind the placard to clear the jack and allow the jack to be supported by the placard and provide insulation as well. There are some nice double-sided-sticky tapes to mount the placard. How thick is your panel and how much thicker could it be and still allow the jack to be installed with it's existing bushing length? Bob . . .


    Message 15


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    Time: 02:13:56 PM PST US
    From: PWilson <pwmac@sisna.com>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: PWilson <pwmac@sisna.com> Bob, and bigger alternators are available, for example: 14v alternators for the auto after market come in 150a (2100 watts) - a Denso, and 200a (2800 watts) - a Powermaster. Lots of power out there at 14v if one needs it. Regards, Paul ================= At 09:55 AM 9/9/2005, "Robert L. Nuckolls, III" wrote: >---snip--- > EXACTLY! You have a driving need for 28v system NOT > for lighter wire, NOT for better cranking but for > POWER. You're running a lot of electric heat and accessories > with some extraordinary demands. Do you have an air-conditioner > too? > > The builder needs to look at a 60A, 14v alternator (840 watts) > and decide what system requirements may require continuous > loads that exceed about 75% of that value (25% headroom for > battery charging). So, if 630 watts is not enough to run > things, then one should consider whether or not a 100A alternator > will suffice or is it better to go 28V at 60A (1680 watts) > or even the system you've installed (2400 watts).


    Message 16


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    Time: 06:58:23 PM PST US
    From: Ken <klehman@albedo.net>
    Subject: Re: Use a 28vdc alternator in 14vdc system?
    --> AeroElectric-List message posted by: Ken <klehman@albedo.net> I believe the answer is both. For a device that is mostly current limited I would not expect much difference between 12 and 14 volts. Ken Mickey Coggins wrote: >--> AeroElectric-List message posted by: Mickey Coggins <mick-matronics@rv8.ch> > > > >> The builder needs to look at a 60A, 14v alternator (840 watts) >> ... >> >> > >Are most alternator current specifications given assuming >14v? I'm planning on using this one: > >http://www.ecae.com/alt1.html > > 2025 Ultra Mini Alternator > >The text says this: > >East Coast Auto Electric UltraMini 12 Volt Series MINI-ALTERNATOR >The UltraMini Alternator is the smallest in our line. It weights only 6 >Lbs. and has an output of 55 amps. > >Is there a way I can find out if the 55 amps number is assuming >12v or 14v? > >Thanks, >Mickey > > >


    Message 17


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    Time: 07:18:29 PM PST US
    From: <robert.mccallum2@sympatico.ca>
    Subject: DC to DC converter
    --> AeroElectric-List message posted by: <robert.mccallum2@sympatico.ca> Hi all; Does anyone have a schematic available, or know of a source for a small, inexpensive 12 VDC to 24 VDC converter capable of supplying approximately 30Ma @ 24 VDC? I do not want a high power device as this will be a dead loss system operating from a 4 Amp-Hr VRLA battery and long operating time is important. (the less draw on the battery the better) The device I need to operate is a light source rated 10 to 30 VDC which is part of a photocell system. This is currently operating successfully on 12 volts but at this voltage doesn't provide quite enough range. I've demonstrated to myself that 24 volts increases the range sufficiently, and I suppose that I could double up on the batteries to get the 24 volts but this creates other difficulties of size and complexity which we won't delve into. Thanks in advance if anyone can help. Bob McC


    Message 18


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    Time: 09:03:45 PM PST US
    From: "Robert L. Nuckolls, III" <nuckollsr@cox.net>
    Subject: Re: mini jack source
    --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckollsr@cox.net> At 01:16 PM 9/9/2005 -0500, you wrote: >--> AeroElectric-List message posted by: "Jim Baker" <jlbaker@telepath.com> > > > I just performed this test and, sure enough, the strobe noise went > > away when the jack was out of the panel. > > > > So, I'm back to my original question which is how to elegantly >isolate > > this jack from my panel. > >Look for a company called Small Parts Inc. online. Search for >shoulder washer...made of nylon. > >For those interested in unique small parts, get their free catalog. Good item Jim, I'd forgotten about those guys. I've used them a lot in the past for small gears and shafts. Bob . . .


    Message 19


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    Time: 09:08:28 PM PST US
    From: "Mike" <mlas@cox.net>
    Subject: mini jack source
    --> AeroElectric-List message posted by: "Mike" <mlas@cox.net> At 01:24 PM 9/9/2005 -0400, you wrote: > --> AeroElectric-List message posted by: Robert Dickson > <robert@thenews-journal.com> > > this is a good and obvious test, one I should of thought of myself. > > I just performed this test and, sure enough, the strobe noise went away > when the jack was out of the panel. Beware the evil ground loop! > So, I'm back to my original question which is how to elegantly isolate > this jack from my panel. Since I have a hole already drilled right > where I'd like the jack I'd really like a jack with isolating washers > just like my headset jacks, if such a creature exists. You could counter bore the hole and mount the jack on to some non-conductive material and then bond it to the back of the panel. This way you would fix the ground problem and the reach problem. And if you did a nice job counter boring (in this process over sizing the hole) it would look flush mounted. Mike Larkin PZL TS-11 Iskra Lancair Legacy Kitfox IV A-320




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