From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: trim vs. a/p
To: lml
Date: Thu, 16 Nov 2006 21:40:49 -0500
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Posted for "colyncase on earthlink" <colyncase@earthlink.net>:

  JHK,
     I don't know.   that's part of what I am trying to find out.
     probably you hook up a signal input to the auto-pilot to the switched 
side
of the trim switch.
   ----- Original Message -----
   From: James H. Keyworth
   To: Lancair Mailing List
   Sent: Thursday, November 16, 2006 9:54 AM
   Subject: [LML] Re: trim vs. a/p
  
  
   Colyn:
  
         "...wired so that pilot operation of the trim kicks the auto pilot
off.."
  
   How would you wire it that way?
  
   JHK

[One way would be to use a dpdt relay to control the  A/P circuit and two 3pdt 
relays to control the pitch trim.  Assume that the hot side of all 3 coils are 
each fed by their respective breakers (one for the A/P system, one each for 
the pitch/roll/and yaw trim relays (allowing you to disconnect any individual 
trim suffering a runaway or other fault.) This way you will simply be sending 
grounds to actuate the relays (common prectice).

Starting with the up/down trim switch (typically a momentary contact SPDT 
center off) with a ground hooked to its (center) common you would connect the 
up-switched side to the negative side of the up-trim relay coil.  On the 
up-trim relay use the #1(+) & #2(-) common and NO contacts to switch power to 
the trim motor.  Same thing for the down-switched side of the trim switch to 
the down relay coil, except the the wiring to the trim motor from the down 
relay would have terms 1 & 2 reversed from how they're wired on the up relay 
(ie, 1=-, 2=+), causing the motor to run in the opposite direction.  This gets 
the trims working.

Connect ground to the one side of the A/P engage pushbutton (momentary contact 
SPST NO) and send its other (switched) side in series through the #3 common/NC 
contacts of both trim relays, then out of them to the negative side of the A/P 
coil.  (If "series" doesn't do it for you, here's the path.... ground to 1 
side of A/P pushbutton... wire from other (switched) side of A/P pushbutton to 
up-trim relay #3 common contact... wire from up-trim relay #3 NC contact to 
down-trim relay #3 common contact... wire from down-trim relay #3 NC contact 
to negative side of A/P relay coil... phew.) This way if either trim relay is 
actuated the ground path to the A/P coil from the A/P engage button is broken 
by the opening of the trim relay's #3 NC contact, disallowing the actuation of 
the A/P relay while either trim circuit is operating.  Put a ground to A/P 
relay #2 common terminal and send the #2 NO contact back to the same place you 
sent the switched ground from the A/P engage pushbutton (the first connection 
to the trim relays' #3 contacts, (up-trim relay #3 common contact in the above 
explanation))... this terminal on the A/P relay acts as a latch for the A/P 
relay coil but is first routed through the series connections of the #3 NC 
contacts of the trim relays, once again releasing the A/P with any actuation 
of the pitch trim switch.  I'll try to do a schematic for you... pictures 
always make these things easier to understand.   <Marv>     ]