Automatic DC Data Logging System

A system is described which digitizes dc voltages and records the values on punched cards for subsequent machine data reduction. High accuracy is achieved by comparing the input voltage to a bank of standard cells and measuring the difference. An automatic calibration routine is provided. Resolution is one part per million, stability a few parts per million for a 30-day period without adjustment. Contributions of various parts of the system to over-all error are analyzed. Automatic calibration data are analyzed to establish system performance.