Robert Adams Motor - Stator Core Selection and Back-Drag Tuning

I'm winding my stator electromagnets for the Adams motor. The manual says to use solid soft iron cores. Has anyone tried silicon steel laminations or ferrite instead? Also, what is the best timing for the optical slot card to get the back-drag cancel effect?

Do not use laminated steel or ferrite. You need solid soft iron because the magnetic attraction of the rotor magnets to the solid iron core is what pulls the rotor forward for free. The pulse only energizes the coils to push the magnets away just as they pass alignment, canceling the drag. Laminated steel doesn't have the same static attraction pull.

NZ, that makes perfect sense. I will stick to solid iron rods. For timing, I set the slot to turn on the MOSFET when the magnet is exactly aligned with the core, and stay on for 25% of the rotor cycle. The rotor is accelerating rapidly but my MOSFET is getting hot. Do I need a snubbing circuit?

The heat is because of the inductive kickback (flyback). You must capture this! Connect a fast diode from the drain to the positive rail of a separate battery. This captures the back-EMF spike and cools down the MOSFET instantly while recharging your backup battery.