TBMA Test Boards for MagAlpha™ Sensors Monolithic Power Systems (MPS) TBMA Test Boards for MagAlpha™ Sensors come in two versions, round (RD) and long (LT), allowing users to run and test MagAlpha sensors quickly. In the RD format, the sensor is mounted in an end-of shaft configuration. In the LT format, the sensor is mounted on the edge of the board and can be used in both side-shaft and end-of-shaft configurations.