A night vision system including a power system having a low voltage unit coupled to a high voltage unit. The low voltage unit includes a low voltage controller and a low voltage table correlating pulse widths to step values. The low voltage unit transmits the step value to the high voltage unit in a pulse train having a period corresponding to a frequency. The high voltage unit including an opto-isolator for receiving the step value from the low voltage controller, a high voltage controller accessing a high voltage table correlating step value to pulse width and threshold. The high voltage controller generates control pulses at the frequency in response to the pulse width and the threshold.