An addressable transducer interface which may be associated with a particular electrical transducer, comprises means for storing correction data so that on addressing of the interface by external control means, the correction data may be transmitted to the control means together with measurement data from the transducer. Said correction data may be stored in digital form. The interface includes an analogue to digital converter circuit which comprises means for charging a capacitor, voltage comparator means arranged to compare the value of an analogue voltage signal on an input with the charge voltage in said capacitor, a digital counter arranged to start a count of cycles of a reference frequency, a shift register and a loading circuit arranged to cause the instantaneous count in said counter to be loaded into said shift register. |