A transportation lag circuit for analogue computation

An analogue transportation lag based on the expansion is described. The unit uses n simple phase inverters in cascade, the time delay τ and maximum frequency of operation fmax being related by where RC is the phase-shifting time constant. By means of a simple cross-over unit and high gain d.c. amplifier the delay unit is designed to have extremely low drift. An example is shown which has a transportation lag of 32 ms and a maximum frequency of operation of 150 c/s.