Toroidal transformers for an analogue system of machine tool control

The use of toroidal transformers makes possible analogue computing circuits with an accuracy of a few parts in a million. Among many applications the use of such circuits has proved of great value in the control of machine tools. Some details are given of the transformers and of design procedure, and the simulation of mathematical operations, such as multiplication and interpolation, is shown. A discussion follows of the design of the analogue circuits in a unit used to convert digital information to an analogue signal. Finally some results are quoted of accuracy tests on a system for a skin milling control, showing that during 1,184 readings taken under a wide variety of conditions of temperature and electrical supplies the total error on a 540 in. (13.7 m) axis only exceeded 0.001 in. (0.025 mm) on 0.42 per cent. of the measurements.