Abstract: A stator includes: an annular stator core having tooth portions; an insulator made of an electrically-insulative resin material and covering predetermined parts of the stator core; windings wound on the tooth portions with the insulator interposed therebetween; and terminals made of an electrically-conductive metal plate and connected with end portions of the corresponding windings. The stator is connected to an electrical connection target via the terminals. Each of the terminals has a connection terminal portion axially extending so as to be connected to the connection target, a winding connection portion connected with the end portions of the corresponding windings, and an extension portion extending between the connection terminal portion and the winding connection portion in a circumferential direction. Each of the terminals is supported, with part of the extension portion thereof abutting against a supporting portion of the insulator at a plurality of positions, so as to maintain its posture.

Abstract: A gain of a variable gain amplifier circuit is controlled by applying a signal of a predetermined voltage level to the variable gain amplifier circuit during an idle period of an ultrasonic receiving signal, deriving an output from the variable gain amplifier circuit, comparing it with a voltage level obtained as an aimed value by a gain regulator or other control circuit of an ultrasonic signal amplifier circuit including the variable gain amplifier circuit and producing a gain control signal according to a difference resulting from the comparison to control the gain to the aimed value until the difference becomes zero. The gain of the variable gain amplifier circuit set in the idle period is maintained during a measurement period of a subsequent receiving signal so that the latter is amplified with the maintained gain. Thus, a stepwise and selective gain setting corresponding to the aimed value can be obtained by controlling the gain of the variable gain amplifier according to the aimed value.