The LHi 874 and LHi 878 pyroelectric infrared-detector series are the standard dual element design recommended for all variants of motion control.They include a dual element pyro-electric ceramic with FET in source follower connection. The LHi 874 is available as TO-39, whereas LHi 878 detector is available in TO-5 housing with standard infrared filter. They both offer high responsivity with excellent common mode performance (match) and low noise at steady state and temperature changes.