Mailing List lml@lancaironline.net Message #69063
From: Louis Gabriel <louis@gabriels.us>
Sender: <marv@lancaironline.net>
Subject: New gear indication system
Date: Sat, 25 Jan 2014 17:02:29 -0500
To: <lml@lancaironline.net>
Hey everyone!

So, my 360 had what I assume is the stock Lancair landing gear indication system--micro switches, incandescent gear lights, and a bunch of wire splices.

After more indication failures than I can count (and no actual landing gear problems), I decided a redesign was in order.  Here were my goals:
  • Proximity sensors instead of micro switches--zero moving parts, completely weatherproof, nothing to wear out, gum up, or break.  Commercial jets have used prox sensors for decades, and it's just a better way.  If something metal comes within 1mm of the face of the sensor, it will turn on.  Period.
  • LED lights.  Preferably ones that I could dim and press-to-test.
  • No wire splices anywhere.  I wanted to run everything to mil-spec connectors (settled on D-Sub).

So I designed a circuit, prototyped, ordered parts, screwed up, tried again...until I had a little box with a DB25 connector on the side.

Here's a brief list of features:

  • Works with either prox sensors or existing micro switches
  • Has diode-isolated power inputs, so you can feed it from one or two electrical sources
  • Will drive three green and one amber press-to-test, dimmable LED lights (NLG, RMG, LMG, and Gear in Transit)
  • Safety first:
    • All components are made from self-extinguishing materials
    • Everything is potted in epoxy for vibration and chemical proofing
    • All electrical components are at least 150% oversized.  (Each lamp draws approximately 7 mA, everything on the board is rated for 1 A or above)
    • PCB manufactured in the U.S., enclosure is Canadian, and majority of components are Amphenol or Tyco
  • Route all your wires to one place, crimp on contacts, plug them in...and you're done.  No splices!  The box only requires +12V, GND, and the Gear in Transit connection from the gear relays.  Everything else is self contained.

I'd love to share all my character building with the community--if there's any interest, I'll make a batch.  Price would obviously depend on quantity, so if you're building or are interested in a retrofit...let me know!

Pictures should be attached below, if not, let me know and I'll throw up a quick gallery somewhere.

Louis
louis@gabriels.us






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