Differential transformer for register- ing linear movements utilizing bridge circuit windings and means for cali- bration

Claim 1

AN ELECTRIC MEASURING DEVICE FOR MEASURING RECTILINEAR DISPLACEMENT OF A BODY, SAID DEVICE COMPRISING: A DIFFERENTIAL TRANSFORMER HAVING A PRIMARY WINDING AND TWO SECONDARY WINDINGS WOUND ABOUT A CORE WHICH IS LENGTHWISE DISPLACEABLE IN ACCORDANCE WITH THE DISPLACEMENT TO THE MEASURED, A FIRST BRANCH CIRCUIT CONNECTED IN PARALLEL WITH SAID PRIMARY WINDING, SAID BRANCH CIRCUIT INCLUDING ONE OF SAID PRIMARY WINDING, SAID BRANCH CIRCUIT INCLUDING ONE OF SAID SECONDARY WINDINGS AND A FIRST ING AND SAID FIRST RESISTANCE MEANS BEING DIMENSIONED SO THAT THE INDUCTANCE OF SAID SECONDARY WINDING IS VERY SMALL AND LESS THAN THE INDUCTANCE OF SAID PRIMARY WINDING AND THE RESISTANCE OF SAID FIRST RESISTANCE MEANS PROVIDES A VERY HIGH VALUE OF SHORT CIRCUIT RESISTANCE, A SECOND BRANCH CIRCUIT IN PARALLEL WITH SAID PRIMARY WINDING, SAID SECOND BRANCH CIRCUIT INCLUDING THE OTHER OF SAID SECONDARY WINDINGS AND A SECOND RESISTANCE MEANS IN SERIAL CONNECTION, SAID OTHER SECONDARY WINDING AND RESISTANCE MEANS BEING DIMENSIONED SO THAT THE INDUCTANCE OF SAID SECONDARY WINDING IS VERY SMALL AND LESS THAN THE INDUCTANCE OF SAID PRIMARY WINDING AND THE RESISTANCE OF SAID RESISTANCE MEANS PROVIDES A VERY HIGH VALUE OF SHORT CIRCUIT RESISTANCE; A SOURCE OF A.-C. VOLTAGE CONNECTED ACROSS SAID PRIMARY WINDING; AND THE JUNCTION POINT OF THE SECONDARY WINDING AND THE RESISTANCE MEANS IN ONE BRANCH BEING ADAPTED TO TRANSMIT A VOLTAGE AND THE JUNCTION POINT OF THE SECONDARY WINDING AND THE RESISTANCE MEANS IN THE OTHER BRANCH BEING ADAPTED TO TRANSMIT A VOLTAGE WHEREBY THE OUTPUT VOLTAGE DEVELOPED ACROSS SAID JUNCTION MEANS IS INDICATIVE OF THE POSITION OF DISPLACEMENT OF THE CORE IN REFERENCE TO SAID SECONDARY WINDINGS.