Abstract: A fiber optic optical rate sensor includes two channels, each of which provides an angular rate signal, and a light source common to the two channels. The channels are oriented in opposite directions whereby the angular rate signals are added and noise signals are subtracted. The output of the sensor is the result of the subtraction of the outputs of the two channels whereby common mode noise is minimized.

Abstract: A series pass battery charger is disclosed which comprises at least two input voltage sources, a series pass element and a power dissipation control circuit which is operatively connected to the series pass element. The power dissipation control circuit senses the voltage difference between the input voltages sources and the DC output voltage of the battery charger and controls the voltage applied to the series pass element. During periods of excessive power dissipation, the control circuit decreases the amount of the input voltage applied to the series pass element thereby greatly reducing the power dissipated.

Abstract: A support for a vertically hinged door including a bracket affixed to the lowermost free corner of the door and a pivotable support leg attached to the bracket for automatic movement between an extended support position and a horizontal stored position is disclosed. The support is provided with a stop and automatic latch for retaining the support leg in the support position.

Abstract: A battery charger failure alarm circuit for use with a battery charger including a source of rectified AC voltage for charging a battery and a filtering inductor serially interposed between said charger circuit and battery and across which there appears AC ripple voltage so long as the battery charger is functioning properly, includes a sensing circuit coupled to the filtering inductor for sensing the presence of the AC ripple voltage and an alarm circuit coupled to the sensing circuit operable to indicate the failure of the battery charger circuit in response to a lack of sensed AC ripple voltage. A time delay circuit may be included in the battery charger failure alarm circuit between the sensing circuit and alarm circuit to delay the operation of the alarm circuit in the case of momentary loss of the AC ripple voltage.