AeroElectric-List Digest Archive

Sun 08/27/17


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 08:49 AM - AEC 9009 Audio Iso Amp for sale (Jared Yates)
     2. 10:25 AM - Re: Tips for Building a Wiring Harness (Bill Watson)
     3. 05:38 PM - Re: Re: Non-aero app: 120/240 AC through 24vdc switch? (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 08:49:02 AM PST US
    From: Jared Yates <email@jaredyates.com>
    Subject: AEC 9009 Audio Iso Amp for sale
    I built this little circuit to Bob's specs here: http://www.aeroelectric.com/Catalog/AEC/9009/ and it worked great for 250 hours. I've recently replaced it with an audio panel due to some other equipment upgrades. This circuit allows you to consolidate up to 5 channels of audio into a single audio output, which can then be fed into an intercom's auxiliary input. In my case I used it for left entertainment, right entertainment, VHF nav ident, and Dynon audio. The volume of each channel is adjusted by replacing the resistors. Asking $40 shipped (cost of materials), please reply directly if you are interested. Thanks, Jared


    Message 2


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    Time: 10:25:39 AM PST US
    Subject: Re: Tips for Building a Wiring Harness
    From: Bill Watson <Mauledriver@nc.rr.com>
    A bit OT but I think many builders could benefit from the following approach (pun) if they understood what it does. My 'harness' was done with the Approach Fast Stack <http://www.approachfaststack.com/> hub and cables. The panel includes (3) GRT HX EFISs, G430w, G327 Trpdx, PS Audio box, Garmin SL30, and a Trutrak AP (all vintage 2009-10). I ordered the components directly and through various channels (including Fast Stack I recall) but in every case I did not order any kind of harness for any of them. Instead I supplied the Approach folks with my list of equipment. They asked a few questions and came back to me with their standard Pro Hub and a list of the customized cables required for the panel and the desired functionality. Truth be told, I didn't fully understand which connections were required for which functions, which were redundant, which were unnecessary. I certainly didn't have what I needed to plan all the connections between certified products like the Garmins and experimental products like the GRTs. Challenges included the fact that Garmin primarily supports their dealer network and GRT documentation always lagged a bit behind delivery of functionality. But the folks at Approach fully understood what connections were required and did things that took me a year or more to fully understand how complete a job they did. And all I had to do was to mount their hub under the panel, plug in the cables, and wire a handful of power and ground pigtails to my electrical system. The hub is a hardware-only device that looks like a collection of D-Sub connectors. There's a cable from each panel component to the hub with no direct component to component connections. Upgrading or replacing a component generally just involves getting a new cable from Fast Stack. And perhaps most valuable of all, the entire 'harness' is fully documented for your installation. Any of you that have installed a full IFR panel with full Nav, RNAV, and a 2 axis AP functions know that it takes awhile to learn your way around the many capabilities. The good part is that I found every single necessary connection and option had been wired up correctly and reliably through the Fast Stack hub and cables. I just wish it could have pushed all the necessary buttons at the right time. Doing a DIY panel still involves a lot of planning wiring, labeling and documentation. Using Fast Stack still qualifies as a DIY panel with all the satisfaction and $$$ savings that can be realized.... and a whole lot less headache pain. Looking back after 6 years of flying my panel, I would do it the same way if I did it again. Sorry for hitch-hiking on this thread. Bill "back to paying a bunch of bills and doing paperwork" Watson On 8/25/2017 11:14 PM, Art Zemon wrote: > Folks, > > I have all but two of the components for my instrument panel in-hand > so it's time to start building the wiring harness. Other than obvious > stuff, like draw it out on paper before starting to solder and crimp, > do you have any tips or suggestions for how to construct this complex > piece of wire and connectors? > > Thanks, > -- Art Z. > > -- > https://CheerfulCurmudgeon.com/ > > /"If I am not for myself, who is for me? And if I am only for myself, > what am I? And if not now, when?" Hillel/ --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus


    Message 3


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    Time: 05:38:04 PM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Re: Non-aero app: 120/240 AC through 24vdc switch?
    At 12:00 PM 8/26/2017, you wrote: > >Bob, >Here's the schematic, and late breaking...the ballast mfgr engineer >informed me that the max inrush for the ballast is 101 A. Combined >with the Pwr Supply's 40A inrush, rough duty for a 5A switch. > >Thanks for looking at this, >John > Okay, let's talk about 'inrush' currents. Emacs! Here's a simple model of an inrush-energy study that will suffice for this discussion. In reality, the model is much more complex with features (inductances and capacitances) combined with dynamics of the power source and timing . . . if you close a switch at the exact instant the AC voltage is at its peak, then MAXIMUM inrush currents can be expected. On the other hand, if you can somehow close the switch while the incoming voltage is zero . . . then inrush effects on the switch will be . . . uh . . . almost zero. I show two resistances, Rs which is the source resistance. This component sets the maximum current that can flow if a dead short is placed across the source. It also set the requirements for 'interrupt current ratings' on circuit breakers and fuses. Then I've show a load resistance Rl which is controlled by the configuration of your products input components, in this case . . . a combined ballast and power supply. The ballast mfgr has quoted a rather impressive inrush current number . . . which is only partly significant. Consider a range CAPACITORS sized from picofarads to farads. The exact instant that your switch contacts close, the inrush current will be V(applied)/Rs+Rl and may very well be on the order of 100 amps . . . which says NOTHING about the size of the capacitor, only that V is applied over the total resitance for some period of time after contact closure. If C is picofarads, the DURATION of the inrush event is very short, perhaps measured in picoseconds. If C is Farads (like some of those capacitors favored by installers of mobile gray-matter mashers) then the duration of inrush event is orders of magnitude more severe. The ability of a switch to manage that event has roots in contact mass, spring rates of closing forces and velocity of the moving contact mass as it crashes into it's stationary mate. Contact bounce is an inevitable feature of ALL mechanical switches. Further, the severity of bounce is only loosely related to the switches pedigree. Here's a study I did on a system with mil-spec, sealed relays that were GOING to stick irrespective of how well the device was built. http://tinyurl.com/pstsggm As you can see in this article, the sticking wasn't even a high energy event. The relays were being used in a situation well inside their catalog ratings . . . but a combination of capacitance and PROPAGATION delay down and back over a crude coaxial feed line stacked up to offer the 'perfect low energy relay welder'. The 100A inrush value offered by your supplier simply acknowledges that there is some capacitive component across the input to their product . . . but no help for how large it might be. Obviously, the COMBINATION of that inrush energy event and contact bounce on your switch of choice has produced a condition prone to sticking. What kind of switch are we talking about? How long does it take to produce a failure event? Have you been able to duplicate the sticking even in a laboratory environment? Are there a lot of fielded devices that may need upgrading? One sure bet for fixing the problem and staying with your existing switch is to add some electronics behind the panel . . . perhaps a solid state relay with ZERO CROSSING detection that reduces inrush to a minimum. http://tinyurl.com/y7rst4a6 http://tinyurl.com/y8g8zyj9 Another possibility is to change the switch. Just a difference in brand for the same physical switch can make a big difference. Adding to Rl in the inrush loop, either inrush limiter or perhaps just a 3 ohm, 5 watt resistor (1A running current across three ohms is 3 volts drop, 3W dissipated . . . but a reduction in inrush MAGNITUDE by a factor of 3 or more . . . with an insignificant change in over all performance. Making the elegant decision demands more data. Perhaps 'scope traces on the inrush event. A study of bounce characteristics of the switch. Better data on exactly what the inputs to your loads look like will help. But it seems likely that a change in brand/style of switch is the shortest path and perhaps even doable as a field retrofit. The elegant equation demands a lot more 'numbers' Bob . . .




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