Electrical System Design and Build

[Carl Froehlich]

Originally Posted by leok

. SNIP
I do (with respect) challenge the refrain "single point failure" as used in the context of the VPX. If I understand the architecture of the VPX Pro properly, there are two fully separate internal electronic busses. Other than one power wire attaching to the box, there is no "single" failure that would take the VPX completely out.
Good planning will split redundant critical functions between these. I also don't feel that I have spent any significant money, only thought, logic and a few wires to add layers of redundancy while incorporating the VPX Pro. I'm not trying to be a pain here, just accurate. Please correct me if you think I am wrong.

Leok,
Correct - loss of the power lead or the ground lead and you lost the VPX and everything it runs. Just like if your single Master solenoid or Avionics Master switch failed on a legacy electrical distribution design.

As you point out you can do a work around by adding dedicated busses that bypass the VPX (or perhaps use two VPX boxes) and I encourage anyone using a VPX like box to do so. I'll stick with what I consider a simpler, cheaper and more robust approach to achieve "no impact or at most graceful degradation" when any single component fails.

I'm now stepping off my soapbox,
Carl

[rockbottom]

Leo,

Sent you an email concerning some of the GMA 245 interconnects. Please let me know if you didn't receive it.

Regards,
J. Baker
RV8 Finishing

[leok]

I did receive it. It is on my work email and with the weekend, well, I didn't see it until today. It will take a few days to research and comment back.

[Bill Boyd]

Leo,

I want to jump in here and thank you publicly for the use of your overhead console mold, which you generously made available to me and even covered significant shipping expense to get this to a complete stranger with the only stipulation that I pay it forward to the next user.

I have made my overhead (it was as you warned me a lot of work to finish the tool surface since I didn't vacuum bag it.) It weighs about 3lb 8oz. I was very pleased. The mold is at its new home in Jack Phillips' hangar at W91, where he is himself almost ready to pass it along to the next fellow in line. Thanks from both of us for sharing your labor! Also appreciate you making your electrical design deliberations available to the VAF clan in this thread. Good community

[leok]

Bill,

Glad to hear things went well with the mold. It is even better to see that it has another user. It beats having it kicking around the shop gathering dust until I threw it out to make room.

By the way if anybody wants the mold to the center stack close out or center console (look in my build log to see what the parts looks like) , I'll make the same deal ... just pass it on is someone else wants to use it.

Makes me wish I spent more time getting a perfect surface.

[leok]

Originally Posted by rockbottom

Leo,

Sent you an email concerning some of the GMA 245 interconnects. Please let me know if you didn't receive it.

Regards,
J. Baker
RV8 Finishing

Based on your comments I checked the GMA245 drawings and found you are correct.
I have (had, fixed now in my drawings and I will repost a corrected version) pins 5 and 20 at the GTN650 P1003 connector switched (Lo MIC should splice into Lo COM) and the same with the GMA245 connection to pins 36 and 17 on the GTR20 P2001 connector (again Lo MIC should splice into Lo COM)

I think the MAPMX reference on the GTN650 to G5 RS232 connection was just a copy error on my part as I copied/pasted blocks to construct the drawings. I missed deleting the MAPMX label. I find no reference in the G5 installation manual that indicates how the RS232 should be configured as. I will check with GARMIN to see what they recommend and let you know after I talk to them.

[leok]

I updated the wire diagrams based on new information. I added a fan output and configuration module to the GTN-650. The new link is:

https://drive.google.com/file/d/0BxZ...ew?usp=sharing

Garmin can be a little frustrating in relation to connectors for their avionics. Some come with the component, some are purchased separately as install kits, some are not available at all to the experimental installations. If they are reading this, it would be a good thing to simplify for us builders. Specifically the GTN-650 has no connector kit available, at least through Aircraft Spruce. They sell it only with a pre-fabricated harness. And, if you don't want a pre-fab harness ... well .... Stein to the rescue!

Stein set me up with the install kit from a GTN-650. It includes 4 connectors, a rack mount, a config module and the back plate/fan. Other than a handling fee, I will get a credit from Stein when I purchase the GTN-650.

The GTN-650 is now fully installed.

Thank you to Stein.

[PipeDreamer]

Started to think about electrical and didn't know where to begin....
Thank you for sharing your PPT LeoK !!!

[leok]

You are very welcome Alex.

Just be aware I have yet to test all of the connections. One correction I have yet to make is the power leads to the GTN650. There are 6 pins directed to power in. I mistakenly thought they were primary and back up power (in sets of two for the Nav/Comm/GPS like other Garmin instruments) and they are that way in the diagram.
In reality they are all primary power in, so need to be spliced together. Three sets of two. They are that way because of the size/power limitation on the high density pins. I will end up feeding back up power through a diode for redundancy.

[kthom_441]

Why am I a year behind in these conversations ????

Thanks for this detailed presentation of your electrical connections and the discussion. I had one question about the primary power diagram. At least in the latest I've found, you are powering your Battery Buss (Switched) through your master switch. This leaves a variable load, including the Fuel Pump, going through the switch contacts. Why didn't you connect to the switched side of the Battery Relay? I would expect the relay contacts to be considerably more robust and reliable than the switch contacts.

Thanks much
Ken
RV-9A
N729KT (Reserved)