BPS-55 BPS-55 is an inexpensive and high performance digital constant current source suitable for small and medium sized electromagnets. Although the equipment is designed for the Electromagnet, Model: EMU-50T, it can be used satisfactorily with any other electromagnet provided the coil resistance does not exceed 6 ohm. The current regulation circuit is IC controlled and hence results in the highest quality of performance. Matched power transistors are used to share the load current.