Abstract: A miniature vibrator (50) for a wrist (10) worn alerting device (20) such as a pager produces a rocking motion vibratory alert. The vibrator (50) has a pair of cantilevered piezoelectric resonant vibrators (62, 64, 66 and 72, 74, 76) which are driven by separate drivers (34, 38) at a frequency determined by a frequency generator (32) but at opposite phases because of an inverter (36). Since the vibrating masses (64, 74) move in opposite directions (200, 210), translational movement of the alerting device (20) is substantially eliminated and a resulting rocking motion produces an improved vibratory sensation on the wrist (10) of the user. Additionally, driving the resonant vibrators (62, 64, 66 and 72, 74, 76) at opposite phases results in reduced surge currents (150) on the battery (40).

Abstract: A detector circuit (301) is utilized in a DC to DC converter (300) having an inductor (356) coupled to a switch (358) for interrupting an electric current through the inductor (356), thereby allowing the inductor (356) to transfer stored energy to a capacitive load (364). The detector circuit (301) includes a capacitor (302) coupled to the inductor (356) for generating a transient current (428) in response to a completion of a transfer of stored energy from the inductor (356). The detector circuit (301) further includes a reference current generator (306) for generating a reference current, and a summing node (304) coupled to the capacitor (302) and coupled to the reference current generator (306) for summing the transient current (428) and the reference current. The two summed currents form a transient control current (436) responsive to the completion (424) of the transfer of stored energy from the inductor (356).