Does anyone know of a sensor that determines position, feeds back a
 signal
 to both allow position and preselection of motion? I am trying to
 fabricate
 a flap handle that when put in a position (say 30 deg flaps)
 actuates the
 motor; the sensor senses when the motor (flap) is there and then
 shuts off.
 Seems to me cowl flap linear actuators might do that? But I already
 have a
 motor and a way to sense flap position. I just need to feed it back
 and
 control it at the flap handle.
 Marc

 Any potentiometer will work as a sensor.
 http://parts.digikey.com/1/parts-kws/a-250k-potentiometer

 Paul Lamar

 Out put stage attached. The word I was looking for was voltage
 divider for the flap position selector switch. You will need a pot
 with as many turns as ball screw shaft (or proportional gearing).
 C. Smith


Paul,

Here is a decidedly simple and low-tech way to accomplish it:  let us define
a "knife" type switch as consisting of female "contacts" and a male "blade"
which closes an electrical circuit when the blade slides between the con-
tacts.  The blade is directly attached to the flap position indicator,
visible through a slot on the panel.  Two sets of contacts are attached to
the flap actuator handle...one set above, and another set below, with a gap
in bet- ween.  When the flap actuator handle is moved, it engages the blade
and the flaps move until the blade reaches the end of the contacts and then
stops.  The upper set of contacts make the flap go down, the lower set makes
the flap go up.  If you don't want to route the actual flap motor current
through the panel, you can use relays.  I am not sure how this device will
function when the blade is exactly at the end of the contacts, whether there
will be intermittent contact, sparking etc.  but I am sure there are many
ways to deal with these issues.  For example, you could spring-load the
blade so that once it reaches the end of travel, it will tend to
self-release even further.  Hope this idea spurs us on to much better ones.

Gene Kahn

--
Gene,
That is almost exactly the scenario Cessna used on some models. A moving
cable fed back flap position to the "flap lever", which consisted of sliding
plates on a cam, one leg attached to the flap preselect lever. 3
micro-switches mounted to the sliding plates set determine when to shut off
the motor, either up or down (10/15/30 degrees)! A nightmare to keep in
adjustment accurately as the interaction of the moving cable, the micro
switches and the lever all contribute
I want to get away from that. Need a better mousetrap.
Marc