Thursday, January 20, 2011

Wiring an ultralight instrument panel into an Ultralight Aircraft

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Let's wire up an instrument panel, using Belite' featherweight avionics.  Our completed panel will weigh about 12 ounces (0.35KG), and it will look like this:

That's a lot of functionality.

Anyway, let's build it.  We're starting with our precision machined aluminum panel,

which looks like this:

And in order to make it beautiful, we can paint it using a high quality metal compatible paint.  But for this panel, I chose to give it a couple of coats of clear lacquer, and it looks gorgeous.  (The aluminum is brushed.)

Let's gather up some switches.  We need an ignition switch, two mag switches, a master avionics power switch, and a dimmer switch.  Here's some switches, which we purchased from Radio Shack:

The thing on the left is an inline fuseholder, which I have put a 1/2 amp fuse into.  The red switch is a pushbutton switch.  The other four switches are single pole, single throw switches.

Now let's attach the switches to the panel.  Here's a view from the rear of the panel:

We'll need a wire harness for the kill switch hookup.  Here it is, and it came from a standard hard drive power connector.  The red wire will be the Right magneto, the yellow is left, and both blacks will be grounds.

And let's wire some high quality small gauge red wire to the panel.  This wire will be switched power, and it will route to all of the instruments, and to the dimmer switch.  One of these wires is about 3 inches long, and the other is about 12 inches long.  They are wired to the center post of the avionics master power switch, in the photo below:

Now a side note on wiring technique:  I try and make a neat, very high quality solder connection, and then cover with heatshrink.  I won't mention this basic technique again.

The red wires attached to the switch will be routed to the dimmer switch and to all the instruments.  Just keep watching the photos...

The short red wire has been attached to the dimmer switch.  The kill switch harness has been wired to the two kill switches.

Let's gather up the loose instruments which we've chosen to install in this panel.  Here they are:

and now let's remove the wire plug from the rear of each one.  And we'll also loosen the 2/56 screws on opposing corners, so they are ready to screw into the panel:

And let's screw them into the panel.

Don't forget to put in the LCD voltmeter:

 And here's the voltmeter from the rear, showing the brass press clip that holds it in:

Here's a look at the backside of the same panel:

Now let's plug those connectors back into each plug.  It will look very very scary:

Now that is a nasty looking mess.  Out of spite, I chopped off the end of each power connector, and then I wired all of the power leads together (they are red).  I soldered them....:

And then I soldered them to the single 12" red wire from the master power avionics switch.

And so the power is routed to all of the instruments.

Now we repeat this exercise for all of the grounds from each instrument:

I wired and soldered all of the grounds to about 3 feet of black wire.  This wire will ultimately be connected to ship ground.  You can see the wire falling off the right side of the photo, above.

And below is a picture of the dimmer leads connected together.

And then I connected all of the Dim leads together.  New production instruments are all yellow wires on the Dim lead; but in this production run, some were yellow and some were black.  All are marked with a "D" on the dimmer lead.

The dimmer lead is then connected to the dimmer switch.  When the dimmer switch is on, all of the instruments will Dim.

And here is the completed assembly.

a)  the power leads are attached to the master avionics power switch;
b)  the ground leads are wired together and then to a 3 foot black wire
c)  The dimmer leads are tied to the dimmer switch
d)  the starter switch has been terminated to a couple of connectors, for easy wiring into the ship
e)  the mag kill switches are ready to wire to the engine
f)  the EGT/CHT connector is ready to attach to EGT and CHT probes
g)  the Fuel Gauge has one loose wire -- ready to wire to the fuel probe in the tank
h)  the ASI is ready to accept the plumbing line from the pitot tube (it will be tight -- THE PANEL MIGHT NEED FILING for clearance)

Let's take a look at the finished product.  I've added a plastic plate which covers the one open position.

Then I hooked it up to a battery and turned it on:

So cool.  You can buy these individual instruments (and our bare panel, in a big and small version) from our web store, or from our distributor, AircraftSpruce.


Hausding, Sid said...

Outstanding information and pictures. First time I have seen a manufacturer actually "show and tell". Thank you for the postings and info.

aliah said...


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