Drift compensated d. c. integrator having separate selectively insertable feedback loops

Claim 1

A DRIFT COMPENSATED DIRECT CURRENT INTEGRATOR COMPRISING: A DIRECT CURRENT AMPLIFIER HAVING INPUT AND OUTPUT TERMINALS; A FIRST FEEDBACK LOOP INCLUDING AN INTEGRATING CAPACITOR CONNECTING SAID OUTPUT TO SAID INPUT; A SECOND FEEDBACK LOOP PROVIDING A DIRECT CONNECTION BETWEEN SAID OUTPUT AND SAID INPUT; A TRANSFER RELAY WINDING IN SERIES WITH SAID INTEGRATING CAPACITOR HAVING ONE TERMINAL GROUNDED; SAID TRANSFER RELAY HAVING A TRANSFER CONTACT IN EACH OF SAID FIRST AND SECOND FEEDBACK LOOPS WITH THE CONTACT IN SAID FIRST FEEDBACK LOOP BEING NORMALLY CLOSED AND THE CONTACT IN SAID SECOND FEEDBACK LOOP BEING NORMALLY OPEN, WHEREBY SOLELY ONE OF SAID FEEDBACK LOOPS IS OPEN-CIRCUITED AT ANY GIVEN TIME; SAID TRANSFER RELAY HAVING PARAMETERS OF A VALUE SUCH THAT SAID RELAY IS ENERGIZED AT A PREDETERMINED LEVEL OF INTEGRATED OUTPUT SIGNAL FROM SAID CAPACITOR; AND MEANS FOR REVERSING THE STATE OF SAID CONTACTS A FINITE PERIOD OF TIME AFTER SAID TRANSFER RELAY IS ENERGIZED.