Abstract: A controller for controlling SCR's used for supplying power to loads, which provides digital control of the phase angle of the firing signal for SCR's during rapidly changing frequency of applied power. The digital control is based upon clocking signals which are derived directly from the rotation of a generator to always provide a set number of pulses for each electrical cycle independent of time (frequency).

Abstract: Improved circuitry or systems for the continual testing of the ability of a radiation detection system to detect radiation whether the radiation source being used for the testing is located externally to or is located within the same housing as the radiation detector. The improvement includes means for maintaining a constant voltage upon a control member which means provides accomodation for random or spurious radiation by controlled excitation of a radiation source which provides means for monitoring this radiation source for automatically determining the operational condition of the radiation detector.