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  #1  
Old 05-24-2017, 11:23 AM
BruceMe's Avatar
BruceMe BruceMe is offline
 
Join Date: Feb 2005
Location: Shawnee, Kansas
Posts: 804
Default Best master switch saver?

I'm handy with electronics and I'm sick of killing my battery because I forget to turn off the master... I know, this is a "millenial problem" like FADEC and glass panels. But it's getting old and a $5 circuit can fix it.

Requirements:
  • Must not accidentally turn off on final after a long flight (simple timer)
  • Must have very-very low current when off (<1pA)
  • Be cheap and reliable
  • Avoid failing-off... ie if it dies, stay on

Design

Use a micro-controller connected to a sensitive vibration detector that resets a one-hour timer. After one hour of near-total-non-movement or 2 seconds of holding the power-switch; then collapse the power supply and de-energy the master solenoid. An LED would indicate "On" when solid, blink when in some state of turning-off.

It would be installed in place of the master switch on an aircraft and could be built using a single LED momentary switch.






Components;

I'll post an updates as I'm building and when it's done.
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  #2  
Old 05-24-2017, 11:37 AM
krw5927 krw5927 is offline
 
Join Date: Aug 2010
Location: Wichita, KS
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Default

I'm imagining a simple piezo buzzer mounted out of sight behind the panel, and powered by the master bus through the normally-closed side of a standard oil pressure switch.

Same principle as the "Low Oil Pressure" annunciator light in common use. A light can be easy to miss. An annoyingly loud buzzing noise, not so much.
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  #3  
Old 05-24-2017, 11:47 AM
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FasGlas FasGlas is offline
 
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Default

Or you could just put a pressure switch under your seat (like cars have for seatbelts), connect it to the master power and a piezo horn. As soon as to get out and the master is still on the horn blows... I'm not sure I would trust the only source for aircraft power on a handful of sensitive electronic parts. IMHO.
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  #4  
Old 05-24-2017, 11:56 AM
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Default strobes

I always leave my strobes on - can't miss those when I forget the master.
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  #5  
Old 05-24-2017, 11:58 AM
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Default

Quote:
Originally Posted by rv8ch View Post
I always leave my strobes on - can't miss those when I forget the master.
Same here ...
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  #6  
Old 05-24-2017, 12:06 PM
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BruceMe BruceMe is offline
 
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Default Thanks

Buzzer is simpler and I've had one like that, I've had this idea for a long time. And it's never after a flight that I leave the master on... it's after working on it.
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  #7  
Old 05-24-2017, 12:39 PM
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Raymo Raymo is offline
 
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Default

My flap motor often reminds me of two things after shutting the engine down
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  #8  
Old 05-24-2017, 12:40 PM
jfrank71 jfrank71 is offline
 
Join Date: Jun 2014
Location: Cotulla, TX
Posts: 179
Default +1 strobes on all the time

Never thought I would leave my master switch on. After 20+ years of flying, it finally happened. So now I fall into the group of people that leave the strobes on all the time. When I get out, strobes will be a gentle reminder that I left the master on. Not sure about the master switch on a timer plan. Sounds like a potential point of failure.

+1 strobes
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  #9  
Old 05-24-2017, 01:07 PM
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tomkk tomkk is offline
 
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Quote:
Originally Posted by tomkk View Post
Same here ...
... although I must admit, the one time I left the Master on I had turned the strobes off to work on the plane.
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Port Orange, Fl
EAA #51411
RV-12 N121TK ELSA #120845; first flight 06/10/2015; 700 hrs as of 02/2020
RV-12 N918EN ELSA #120995 Eagles Nest Project; first flight 05/18/2019
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  #10  
Old 05-24-2017, 01:13 PM
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rv8ch rv8ch is offline
 
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Default car keys

If working on the plane, tape your car keys to the master switch, or hang them on the switch if it's a toggle switch. Can't leave without your car keys!
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