Arri 2 Blimp Motor Controller
Posted 04 October 2008 - 12:03 PM
Next up is building a photocell rig to use the ribs on the backside of the motor to interrupt an LED light beam to a photocell to get a tach signal for a phase lock loop circuit to crystal control the motor...the ABB controller has a zero to 10 volt DC analog input for speed control that's perfect for feedback from a PLL. The motor has 24 ribs on the rotor which would work out to 720 Hz running at design 1800 rpm which should work well for PLL control. I'll use a CD4046 CMOS PLL chip and I'm thinking of using my Tobin Milliframe controller for the reference frequency for the PLL circuit so I can have the best of both worlds; sound sync at 24fps, crystal sync for HMI speeds, video sync (23.976 reference), etc.
Note to Paul B: All my development for the Arri motor should transfer quite nicely to Mitchell three phase sync motors. You would need to create a tach signal for feedback to the PLL but the Mitchell's inching knob would be a good place to start.
Posted 04 October 2008 - 10:03 PM
Posted 04 October 2008 - 11:39 PM
I rather like thinking of myself as the curator of the "Old School".
Any help is appreciated. You may be the champion of many of us, here.