Page 1 of 3 123 LastLast
Results 1 to 10 of 23

Thread: Occupancy Sensor

  1. #1
    rwanttaja's Avatar
    Join Date
    Jul 2011
    Location
    Seattle
    Posts
    1,816

    Occupancy Sensor

    I've had two cases on my Fly Baby where I've left the master out and smoked the battery. I've been contemplating adding an "occupancy sensor" to note when the master is on, but the aircraft is unoccupied.

    I'm looking for ideas on how to sense when there's nobody in the seat without using a sensor on the seat mount or the seat itself.

    I may try to hook a magnetic switch that senses when the stick is aft of the full-down position (gravity moves the elevators down when no one's holding the stick). Might be able to rig a switch to the floorboards, or a light/reflector system that has a beam broken when the legs go into the under-panel area.

    Any ideas?

    The "Alert" portion of the system is still under contemplation. I changed my shut-down checklist to ensure power's off, but find my close calls recently have been when I've turned the switch on to work on the airplane. So I'm not going to add an obnoxious hooter; more like something that chirps every fifteen seconds. Maybe just a damn bright LED.

    Ron Wanttaja

  2. #2
    Sam Buchanan's Avatar
    Join Date
    Nov 2011
    Location
    KDCU
    Posts
    327
    My RV-6 has a large red "Turn OFF the Master You Idiot" light that is wired through an oil pressure switch. There is also an audible alarm (which can be turned off for maintenance) on the same circuit. No need to ask why I decided to add this feature.....
    Sam Buchanan
    EAA Technical Counselor
    The RV Journal RV-6 build log
    Fokker D.VII semi-replica build log
    YouTube Channel

  3. #3

    Join Date
    Aug 2011
    Location
    Alabama
    Posts
    1,828
    I like the idea of a small bright LED right above the switch, tied to the battery master.

    That way a quick look either in or out of the aircraft will show its position.

    Or you could hook an electric buzzer to it. I don't know the decibel levels on these things, but that's the extreme solution.

    Frank "my electric fuel pump is my buzzer" Giger
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

  4. #4
    DaleB's Avatar
    Join Date
    Sep 2015
    Location
    KMLE
    Posts
    360
    Low voltage alarm. Set it to beep/flash if the bus voltage is below 13-something Volts. It will go off any time the master is on and the engine isn't running. For extra credit, a 30-60 second delay makes it less annoying.
    Measure twice, cut once...
    scratch head, shrug, shim to fit.

  5. #5
    rwanttaja's Avatar
    Join Date
    Jul 2011
    Location
    Seattle
    Posts
    1,816
    Some good suggestions.

    I like Dale's suggestion of using the bus voltage as the trigger point. The only (very minor) issue is that my generator-type system doesn't go above 13 volts until the engine's turning up 1800 or so RPM. But that's not an issue if I have a low-key chime-type warning...ain't gonna hear it with the headset on, anyway.

    I have contemplated putting a big light to come on with the master. I spent beaucoup bucks for a fancy light-up toggle switch for the avionics bus (well, $2 more, anyway) and that light just doesn't really show up outside on a nice day. But my main worry is with the plane in the hangar, and in any case, I live in the place where the sun doesn't shine (Seattle).

    But... I'm actually leaning towards putting the light on the OUTSIDE of the airplane. My thought is a big mondo LED pointed out of the left side of the fuselage. That's where the toolbox, workbench, and FBC (frosty beverage cooler) reside. As I mentioned, my main concern is leaving the main switch on after performing maintenance. So I'd aim the light at the places I'd likely be before departing the hangar.

    I'm planning on doing some minor electrical reworking over the next few months, I'll keep folks apprised of what I end up with.

    Ron Wanttaja

  6. #6
    Sam Buchanan's Avatar
    Join Date
    Nov 2011
    Location
    KDCU
    Posts
    327
    Put a strobe (flashing LED) on the vertical tail. Now you have a "turn off the master" reminder and an anti-collision light.
    Sam Buchanan
    EAA Technical Counselor
    The RV Journal RV-6 build log
    Fokker D.VII semi-replica build log
    YouTube Channel

  7. #7

    Join Date
    Aug 2011
    Location
    Marietta, GA
    Posts
    614
    I have a little audible device that is tied to the master. If the master is on, there is a 78 (or is it 72?) dB tone coming from under the panel. The sound is loud enough to notice with the engine off, but the engine drowns it out.

  8. #8

    Join Date
    Oct 2011
    Location
    WA
    Posts
    733
    Like Sam said. I just left the stock strobe switch on at all times. I could hear the strobe firing in the cockpit when the engine was off but with the master still on after parking.

  9. #9
    EAA Staff Joda's Avatar
    Join Date
    Jul 2011
    Location
    Oshkosh, Wisconsin, United States
    Posts
    89
    Quote Originally Posted by Bill Berson View Post
    Like Sam said. I just left the stock strobe switch on at all times. I could hear the strobe firing in the cockpit when the engine was off but with the master still on after parking.
    Yep, this is what I do as well. If the plane has strobes, or even a beacon, just leave that switch on all the time. If you don't notice the flashing lights after you get out of the plane then you've probably got bigger issues than just leaving the master on!!

    But if the plane doesn't have anti-collision lights, you can just imply wire a small lamp into the mater circuit that is on anytime the master is on. We've done this with several planes around these parts. It seems to have worked very well.
    Cheers!

    Joe

  10. #10
    CarlOrton's Avatar
    Join Date
    Jul 2011
    Location
    DFW Area
    Posts
    508
    C'mon, Ron, put a bit of a challenge to it! Set up an IR emitter / detector pair on each side of the cockpit. If you get out and the beam completes, then set off an alarm. Small, simple, and relatively cheap. Plus it gives you something to talk about at fly-ins!

    Carl Orton
    Sonex #1170 / Zenith 750 Cruzer
    http://mykitlog.com/corton

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •