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Canopy Switch

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user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Thu Oct 27, 2011 12:47 pm Post subject: Canopy Switch

A canopy-open indicator light does not help much to remind the pilot to latch the canopy.  The pilot will become accustomed to seeing that light on while she taxies, trying to keep cool with the canopy open.  What is needed is an audio and visual alarm that ONLY activates if the canopy is not latched for takeoff.  I thought about using a microprocessor but am not proficient at programming.  Then I found this LM2907 "RPM Speed Switch".  Although it requires a few resistors and capacitors, all of the active components are contained in one 8-pin IC.  

Here is a proposed circuit: https://lh5.googleusercontent.com/-fI7pwRbufgI/Tqm5F18UY5I/AAAAAAAAAcw/QWs0GHx4q1I/s800/Canopy%252520Alarm.gif

And here is the datasheet for the LM2907: http://www.national.com/ds/LM/LM2907.pdf

Joe

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Joe Gores

Tundra10

Joined: 14 Jun 2010
Posts: 102
Location: Scarborough, Ontario

Posted: Fri Oct 28, 2011 5:40 am Post subject: Canopy Switch

Joe,



This looks like a good circuit, to minimize an important risk.



My concern is the connection between the circuit and the canopy latch  

switch.  Perhaps that would be subject to external influences ?



Bob, could you comment ?  What might be the best change to make this  

DO-160 compliant ?



Jeff Page

Dream Aircraft Tundra #10



 	  Quote: 	
		   Subject:  Canopy Switch From:  "user9253" <fran4sew(at)banyanol.com>     

          A canopy-open indicator light does not help much to remind  

 the pilot to latch

 the canopy.  The pilot will become accustomed to seeing that light on while

 she taxies, trying to keep cool with the canopy open.  What is needed is an

 audio and visual alarm that ONLY activates if the canopy is not latched for

 takeoff.

 I thought about using a microprocessor but am not proficient at programming.

 Then I found this LM2907 "RPM Speed Switch".  Although it requires a few

 resistors and capacitors, all of the active components are contained in one

 8-pin IC.  Here is a proposed circuit:

 https://lh5.googleusercontent.com/-fI7pwRbufgI/Tqm5F18UY5I/AAAAAAAAAcw/QWs0GHx4q1I/s800/Canopy%252520Alarm.gif

 And here is the datasheet for the LM2907:

 http://www.national.com/ds/LM/LM2907.pdf



 Joe Gores

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nuckolls.bob(at)aeroelect
Guest

Posted: Fri Oct 28, 2011 8:39 am Post subject: Canopy Switch

At 08:36 AM 10/28/2011, you wrote:




Joe,



This looks like a good circuit, to minimize an important risk.



My concern is the connection between the circuit and the canopy latch

switch.  Perhaps that would be subject to external influences ?



Bob, could you comment ?  What might be the best change to make this

DO-160 compliant ?



      An astute observation my friend. Let

      me noodle on this a bit . . .

   Bob . . .

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Mike Welch

Joined: 13 Feb 2011
Posts: 272

Posted: Fri Oct 28, 2011 9:06 am Post subject: Canopy Switch

Jeff, Bob N, Joe, everyone else,



  If someone isn't crazy about the mechanical "open/closed switch" in the circuit, would it

be a better (as in more robust) idea to have an optical switch?  A simple tab on the canopy,

properly positioned, could open/close an optical switch as needed.



  Just wondering.......



Mike Welch

On Oct 28, 2011, at 11:24 AM, Robert L. Nuckolls, III wrote:



 	  Quote: 	
		   

 

 At 08:36 AM 10/28/2011, you wrote:

 

 

 Joe,

 

 This looks like a good circuit, to minimize an important risk.

 

 My concern is the connection between the circuit and the canopy latch

 switch.  Perhaps that would be subject to external influences ?

 

 Bob, could you comment ?  What might be the best change to make this

 DO-160 compliant ?

 

     An astute observation my friend. Let

     me noodle on this a bit . . .

 

 

  Bob . . .

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user9253

Joined: 28 Mar 2008
Posts: 1938
Location: Riley TWP Michigan

Posted: Fri Oct 28, 2011 10:41 am Post subject: Re: Canopy Switch

Perhaps it would be better to connect the canopy switch to pin 7.  I think the output will be disabled when pin 7 in grounded.  Is that correct?

  To Mike W., most any type of switch can be used.  The switch is less likely to fail than the pilot's memory.  

Joe

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_________________
Joe Gores

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Oct 28, 2011 12:23 pm Post subject: Canopy Switch

At 12:00 PM 10/28/2011, you wrote:

 	  Quote: 	
		  

<mdnanwelch7(at)hotmail.com>



Jeff, Bob N, Joe, everyone else,



   If someone isn't crazy about the mechanical "open/closed switch" 

 in the circuit, would it

be a better (as in more robust) idea to have an optical switch?  A 

simple tab on the canopy,

properly positioned, could open/close an optical switch as needed.



   Just wondering.......


	


   Another option is a reed-switch operated by a magnet.

   Bob . . .

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fvalarm(at)rapidnet.net
Guest

Posted: Sat Oct 29, 2011 4:04 pm Post subject: Canopy Switch

--

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