A vehicle chassis includes a braking system, an energy conversion system, a steering system and a suspension system wherein each system is operably connected to at least one of a plurality of wheels. The over-voltage protection circuit monitors a voltage across the high-voltage transistor to detect an over-voltage condition of the high-voltage transistor, and turns the high-voltage transistor ON when the over-voltage condition is detected. A base member can be provided for ease in handling the instrument, which may include a ratchet mechanism connected to the sleeve. Another advantage of the tactile sensor is that it allows the dynamic registration of touches, thereby making it possible to determine the relative speed between the sensor and the object and to detect gliding or slipping movements on the basis of detected vibrations. A cavity is provided in the pad to define an area of non-contact on the back of the neck and to receive a secondary coil if present.