Paul,
 Have lost track of where you are up to with an electric
 control for the flaps. AS I mentioned before on our combine harvesters
 we have electric control on the sieves and the rotors which can set
 everything to within a mm. time and again. Went to town today and asked
 the mechanic how it worked. Seems the electric actuator has a
 potentiometer that has an output in volts (1 to 5) that is read by the
 main computer to set the actuator exactly where it should be. He
 suggested that you could hook up the potentiometer up to either lights
 or a volt meter, or whatever is needed to get the required stroke.
 Naturally full stroke would be full flap with no flap fully closed. I
 am sure that a smart bloke like you could figure out how to get what is
 required in-between electrically. Can get the manufacturer of the
 actuator if required quite easily as I think we carry a spare for our
 machine regardless. Neil.


 Take a picture of the flap actuator for me. There are two kinds. Simple
 DC motors and stepping motors. Unlikely it is a stepper but possible.
 Probably just a small DC motor. Hook plus 12 volts to one terminal and
 it rotates one way. Reverse the polarity and the motor rotates in the
other
 direction. The computer reads the one to five volts out of the
 potentiometer and knows where it is as you stated above. The computer
 knows where it wants to go so it applies either plus 12 volts or minus
 12 volts and the actuator moves in the direction it needs to go.

Here is what you need to do to control it. A small volt meter that reads the
pot and displays the info on the instrument panel.  (Or just look out the
side window and look at the flap position.) Then wire a momentary two way
toggle switch center off....  on the instrument panel.  See the enclosed
jpg.  In addition use a circuit breaker switch on the instrument panel so
you can reset it in the air.

http://www.sensata.com/klixon/circuit-breaker-aircraft-7270.htm

If you
forget and hold the switch up or down for too long you can damage the act.
motor.  In that case when the motor bottoms out for a few minutes it will
blow the circuit breaker.  You can then reset the C.B..  Easier than wiring
limit switches or a separate fuse that cannot be quickly replaced.  It might
also blow if you try to move the flaps down at too high of an airspeed.

 I like to use these for most circuits as it saves a lot of wiring work.
 However they are expensive. It is nice to be able to reset the breaker
 while in the air without fumbling around with fuses. I used these
 back in the 1960's on the BOAC 500 winning Chaparral 2F. Sometimes
the problem
 is just a momentary short. These are widely used on airliners.

 Paul Lamar