Right side panel installed.

Fitting the right side panel.

Right side panel on the bench, ready to go in.

Coming down the stretch with wiring and, as things get bundled up, I'm even more mindful of preserving options for the future. Working on the right side panel, wiring up the two auxiliary power sockets (switched and unswitched) I decided that I would put "piggy back" quick tab terminals on these sockets. These terminals came from Mouser, although SteinAir sells some sizes. They will make it possible to tap into either the MAIN BUS and/or BAT BUS from the right side of the panel in the future without having to rebundle new wires all the way back to the left side -- if necessary. I'll put a little light heat shrink on the piggy back tabs until they're needed, to reduce the "live" metal surface a bit.

Piggy back quick tab terminals on the two auxilary power sockets on the right side panel, will allow tapping into either MAIN BUS or BAT BUS from those points in the future, if necessary.

The completed right side panel audio harness.

As usual, I'm waiting on a couple small parts (LED paraphenalia) for the center panel, so I got started on the right side panel, wiring the stereo audio IN jack. (Unfortunately, the PS Engineering PMA4000 audio panel on the center panel is just monaural, so right and left channels will be combined... oh well.) This teeny jack has (5) pins, and is "normally closed." That means a signal (source #1, XM radio in this case) can be routed through the jack to the entertainment audio input by default when nothing is plugged into the front side. When something is plugged in on the front of the panel (source #2, an iPod or whatever) the existing normally closed connection is broken, and the new plug signal is fed back to the audio panel, instead of source #1.

The jack's solder lug terminals are very tiny. With careful cutting and twisting of the metal strands, these 24AWG wires just barely fit through the solder lugs. After soldering, each wire and solder lug is covered with heat shrink -- the beginning step in providing as much strain relief as reasonably possible.

The next photo shows that about 1.5" out from the jack, a short length of larger diameter heat shrink joins the five tiny heat shrinked wires into one audio cable that will go to a 9-pin D-sub interconnect, along with three wires from the Co-Pilot volume control potentiometer to the left. The (5) wires from the 3.5MM stereo audio IN jack have been twisted -- in hopes of adding a modicum of noise cancellation -- with the twists held every 3" or so by a 1/2" length of heat shrink. Then the new "twisted cable" has then been tie wrapped around the nearby threads of the big cigarette lighter socket, to provide strain releive for the audio jack's delicate solder lug terminals. Of course, there's a good layer of heat shrink over the cable, underneath the black tie wrap, to protect those small wires from the socket threads and the tie wrap itself.

Finally, the completed right side panel audio harness. The three 22AWG wires coming from the Co-Pilot volume control add a lot of strength and stability to the final assembly, not to mention a festive motif. 

Tomorrow (Yikes! It's late!) I'll wire up the ground power switch to the left, and a small harness over on the right to connect the Hobbes to the MIOIR and this panel will be ready to install.

This shot shows the (5) wires from the stereo audio IN jack that have been twisted -- hoping to proved a modicum of noise cancellation, and tie wrapped around the nearby threads of the big cigarette lighter socket, to provide strain releive for the delicate audio jack solder lug terminals.

Wiring the stereo audio IN jack. This one has (5) pins, and is normally closed. That means a signal can be routed through the jack when nothing is plugged in (source #1, XM radio here) and when something's plugged in on the front of the panel (source #2, an iPod or whatever) the existing normally closed connection is broken, and the new plug signal is fed back to the audio panel instead of Source #1. The pins are very tiny. These 24AWG wires just barely fit through the solder lugs. After soldering, each wire and solder lug is covered with heat shrink and, about 1.5" out, a larger heat shrink joins the five wires into an audio cable that will go to a 9-pin D-sub interconnect, along with the three wires from the Co-pilot volume potentiometer to the left.

One of the cool features of the EI SC-5 clock is that if you provide one of its special inputs with +12VDC when the engine starts, the clock keeps a non-resettable total time, like a Hobbes. More importantly, if it's given power when the engine starts, it will automagically start the UP timer, providing an automatic flight timer -- very handy for fuel management, not to mention logging. I already have, and want to keep, a traditional Hobbes meter. It's the automatic flight timer function that I want to have.

Of course, the logic for "engine ON" is normally provided by the N.O. contacts of the oil pressure switch. (It would be possible to derive this from the N.C. contacts as well, but they are reserved for the critical oil pressure warning function only.) When the engine starts, and the N.O. switch closes, the N.O. contacts pull +12VDC coming through the regular Hobbes meter to ground, completing the circuit that energizes the Hobbes. Unfortunately, there is no way to directly switch +12VDC ON, because the far side of the N.O. switch goes to ground. So....

I've made the super duper oil pressure switch multi-I/O inverting relay (MIOIR) circuit. The relay coil is wired in parallel with the regular Hobbes circuit, so the relay coil is also energized by completion of the circuit provided by the oil pressure switch's N.O. contact. Voila! Then the load contacts of the relay can then be used to turn on +12VDC power to the clock. It's so neat that I decided to bring out (2) wires for each of the available relay states to the D-sub connector, specifically, two wires that switch power ON, and two that switch it OFF. There won't be a shortage of engine ON/OFF logic now! The downstream sides of both the Hobbes and the relay coil are protected by a dual Schottky diode to avoid back feeding the Hobbes, which is polarity sensitive. The MIOIR looks like this:

The only downside to this arrangement is that, because the relay coil and the power to the relay load contacts are in parallel with the Hobbes (+) feed, they also run on the same 3A fuse that powers the Hobbes. The priority among these things is the regular Hobbes. To make sure that some load on the relay load contacts, like the clock power, doesn't blow the common 3A fuse, I'll put a smaller 1A inline fuse in the wire going to the clock -- and any other small loads I may want to hook up to this gizmo in the future. [I'll add a schematic here later. It really does work. ]