Provided is an engine combustion chamber structure. Parasitic electrical interactions are controlled at one or both interfaces of the IPD either by eliminating metal from the interfaces, or by selective use of metal in parts of the MCM that are remote from the sensitive device components. outside the cabinet for 24 hours before the circuit board is mounted in the cabinet. A control mechanism for controlling the depth of a cut stroke of the inner shaft element is secured to the inner shaft element, and a handle is secured to the inner shaft element. The electrically isolated digital output is isolated by a capacitive isolation barrier.