Rapid-Recording A-C Bridge

A power-factor and capacitance bridge capable of unattended recording has been described. Changes in the specimen may be fully recorded within one second of their occurrence. The bridge may be used in connection with life tests, during treating processes, and for recording tests on large numbers of nominally identical structures, in the process of production. The automatic control circuits described in this paper are not limited only to application to the Schering bridge, but may be used for automatic balancing of practically any other type of a-c bridge as well.