I bought a drag racing parachute for my car in case the throttle stuck, the brakes failed, I couldn't shift into neutral, and the ignition switch failed:-)
How about software the knows what speed is ordered, and when voltage is ramped up to full to compensate it realizes with still no speed change that something else is wrong and commands the engine FET to a preprogrammed slow speed voltage setting. MTH has to do this.
Or a device the records tach output and if it goes to zero opens one of the motor leads (or inserts enough resistance to effectively induce a slow motor speed since no tach signal means full voltage to the motor). This seems simplest since any tach failure, wire break would kill tach output. Once sensed protection is enabled. Stan or John could built this circuit. I just need to patent the idea in case it is a hit! :-) G
