A D-C Wheatstone bridge for multi-terohm measurements with high accuracy capability

A bridge has been designed that is capable, in principle, of measuring multi-terohm resistance values. For measurements above 1010ohms, the ratio arms of this bridge are formed using a Y circuit. When converted to the equivalent delta, this circuit simulates the large ratio values necessary for measurements above the terohm level. The primary advantage of the circuit is that all resistors within the bridge, none of which is greater than 1 megohm, are wire-wound; this results in inherent accuracy and stability.