Frequency-to-Period-to-Analog Computer for Flowrate Measurement

The Frequency-to-Period-to-Analog Computer is a special purpose nonlinear analog computer which accepts an ac voltage of varying frequency, acts upon the period of each cycle, computes the inverse of the time period, e = 1/T, and holds the information for the period of the next cycle. Thus, the output voltage is a level which is proportional to the input frequency f = 1/T computed once for every cycle. The system is accurate to better than ± 0.5 per cent of 2/3 full scale. Application of the computer is described and results presented for fast readout and recording of gas and liquid turbine type flowmeters. Extensions of the circuits used can produce voltages proportional to In t or 1/t2, for time t greater than a small positive number.