The RT8420 is a hybrid precision potentiometer, manufactured by SCAIME. This product features a rotative displacement sensors for measuring the number of rotations made by a shaft. The sensor outputs an analogue signal proportional to the number of rotations by the spindle through connecting the moving shaft to the sensor spindle. The sensors of this product are constructed with simple and compact design, which are mountable under difficult usage conditions. It uses 20mA circuit to produce an accurate and effective electrical signal over all ranges.