A megabecquerel display for an isotope calibrator

A separate extension unit was designed which left the original Pitman instrument intact as far as possible, apart from tapping off voltage lines and operational signals. A block diagram and a circuit diagram relating to the display is shown. The circuit performs three functions: one block autoscales by sensing an under- or over-range reading of MBq, to switch either a 0.37 or a 0.037 scaled analog signal from the calibrator to the new digital panel meter (DPM); another block adjusts the position of the decimal point in the DPM; and a third block buffers the output logic signals to drive the analog switches.