Abstract: A transducer circuit includes a transducer device connected to be driven by a rotary member the speed of which it is required to measure. The transducer device produces output pulses at specific angular positions which are counted by an n-bit counter and which are also used to clock an m-bit latch circuit. Pulses from a clock pulse generator are counted by an m-bit counter, which has its data outputs connected to the data inputs of the latch circuit. An output register is connected to the n-bit counter and the latch circuit to receive an n+m bit code therefrom each time the m-bit counter produces a carry out pulse. Thus the n+m code in the output register contains data relating to the number of pulses produced by the transducer device in the fixed interval between carry out pulses and data relating to the number of pulses produced by the clock between the start of that interval and the instant when the last transducer device pulse was produced.