Avionics: Engine information system connection board

GRT's engine information system (EIS) justifiably requires a number of connections into the EIS.  However, many of those inputs come from sensors which are themselves variable resistors.   Thus the associated integration of those sensors into the EIS require another, fixed, resistor in series with each sensor (had GRT included a "pull-up" on the inputs, this nuisance wouldn't have been necessary).  Additionally, that fixed resistor itself must be held (or "excited" as GRT says) to a known voltage.  Also, other sensors additionally require +12 V, +4.8 V and/or a convenient ground connection.

Rather than creating a mess of spliced-in and soldered resistors/connections, I decided to design a simple board I could mount behind the subpanel for the purpose.  I needed to manage the following connections:

	+4.8 V	Resistor	+12 V	GND
Left Fuel	x	x
Right Fuel	x	x
Oil Temp
Oil Press
Hall Alt	x			x
Hall Batt	x			x
Fuel Press			x
Fuel Flow			x	x

Update 9-Sep-17:  The oil pressure and temperature sensors, having their own dedicated input into the EIS rather than using AUX inputs, do not require the use of pullup resistors.  Those discretes, R3 and R4, should be eliminated in the schematic and remain unpopulated on the board.

Here is the schematic for the purpose.  It's just a boatload of quick connect tabs with a few pullup resistors.

Wanting to make the footprint small, here is what the board design looks like.  Notice that I neglected to provide for mounting holes.  A drill later fixed that, as seen further below.

Images of both sides of an unpopulated and populated board, after I soldered one up.  Update 9-Sep-17: Again, R3 and R4 should be eliminated, lest the oil pressure and temperature readings be incorrect.

After drilling in some mounting holes (since I neglected to add them in the design), I attached the distribution board to the back of the subpanel.  I used nylon screws with standoffs to reduce the probability of shorting to the airframe.  The screws were later affixed with thread-locker.

And here are two pictures showing everything connected.  Much better than soldering and slicing.

For the curious, as in the case of when I designed my panel, I am a proponent of open-source software.  For schematic generation and board layout, I used KiCAD.  There are a myriad of so-called "board houses" that manufacture circuit boards when provided with the CAD files for one's design.  Then it's just a matter of whipping out the soldering iron and affixing the components.