Note: The Type 1 Liverpool Simulator has now been superseded by the Type 2 hardware.
The One Bell Simulator Interface is an integrated interface and sensor for a single tower or dumbbell, which connects to a PC in the ringing room running a simulator software package such as Abel, Beltower or Virtual Belfry. Schematics, Eagle PCB designs, firmware source code and full documentation are available on GitHub, and ready made PCBs are available from OSH Park.
The example shown below is fitted with the standard infra-red sensor. An alternative configuration with a Type 2 magneto-resistive sensor is described in the documentation.