(2020-01-30, 07:07 PM)seandepagnier Wrote: How did you drive the shunt coil of the motor? To make it reverse, current must be the same direction through one coil but not the other... Did you use a bridge rectifier, or is the shunt powered through the clutch?
I was asking myself the same.
There is a detailed, well written explanation of the workings of the Neco and adapting it to a new controller by Daniele Fua:
http://www.nicholson38.org/wp-content/up..._35DR8.pdf
If I understand. The series and shunt coils are always in the same direction (the shunt coil paralleled to the clutch).
The current to the armature is reversed to change the rotation or shorted to brake the unit which presumably occurs between the times when the rudder angle is changing?
"The original circuit (see Figure 1) is essentially made by two changeover relays that take care of powering and inverting the current to the Armature while keeping the current direction in the Series Coil unaffected and short-circuiting the Armature when not powered. The Shunt Coil is paralleled to the Clutch Solenoid and its polarity is kept fixed. The Shunt Coil is powered all the time the autopilot is active, even when the motor is not turning; its function is to act as electromagnetic brake when the two changeover relays short-circuit the Armature of the motor."
(2020-01-30, 01:55 PM)xfactor99 Wrote: Hi Nick,
nice to hear from you and yes we met in November, I remeber you were on the way north ....
It's a great feeling when the virtual and real worlds intersect! I was a bit thrown by the photos of snowy mountains in the background in your dropbox but recognised your dog (!) in the video...
I'd really like to construct a pilot similar to yours. I've looked in to mating up the drive unit with a new propriety control head but I'd like to go the whole way of building a system myself. I accept that there will be a lot of learning but for me that is part of the attraction.
We did the 2000 miles from Ireland without autopilot, just two of us. The long keel is a pain in marinas but great in open water!
I'm interested in how you have managed the limit switches. Given the torque of the motor unit this has been a major concern of mine since I started thinking about a conversion.