Note: The Type 1 Liverpool Simulator has now been superseded by the Type 2 hardware.
The Magneto-Resistive Sensor is based on work by Aidan Hedley, and has no moving or optical parts. A prototype of this design has been in use at Liverpool Cathedral since late 2014. Schematics, Eagle PCB designs and full documentation are available on GitHub, and ready made PCBs are available from OSH Park.
An alternative PCB layout (Type 2), allowing a magneto-resistive sensor PCB to be stacked with a One Bell Simulator Interface PCB, is described in the documentation.