A Current-to-Frequency Converter for Astronomical Photometry
Donald J. Taylor · Review of Scientific Instruments · 1969
A simple current-to-frequency converter has been developed which works directly with photomultiplier currents. It has full scale input current ranges of 3×10−10 to 3×10−6 A. The feedback pulse is a square pulse that is clocked on and off by a continuously running oscillator. Drift in the oscillator frequency is compensated if the oscillator also serves as the time base of the counter used to count the pulses. With oscillator frequencies up to and including 20 kHz the linearity is 0.01% or better and the drift less than 0.01% of full scale per hour.