Abstract: A video lighthead mountable to a video camera and having a dimmer control that varies the intensity of the light output from the lighthead using pulse width modulation techniques. A photo sensor measures the intensity of light reflected from a subject in front of the lighthead. The intensity of light output from the lighthead is adjusted by control circuitry in response to changes in measured reflected light intensity to maintain a constant level of illumination. The adjustment is carried out by modifying the duty cycle of a pulse width modulation circuit. The duty cycle adjustment of the pulse width modulation is also used to compensate for supply voltage variations in order to maintain constant light output.

Abstract: A stand-by power supply for preventing interruption of power to a communication unit, has a first connector for electrically connecting to the unit, a second connector for electrically connecting to and disconnecting from a main battery, an auxiliary battery, and a circuit electrically connected to the first and second connectors and the auxiliary battery for applying the main battery across the load, and responsive to the disconnecting of the main battery from the second connector to apply the auxiliary battery across the first connector.

Abstract: The system comprises first and second input terminals each adapted for connection to a source of charging power, first means for feeding power from the first input terminal to a first terminal of the rechargeable power source, second means for feeding power from the second input terminal to a second terminal of the rechargeable power source. Means are provided for sensing at least one condition of the rechargeable power source and for interrupting the first means for feeding power in response thereto. Third means are provided for feeding power from the rechargeable power source to the first input terminal. The third means includes means for bypassing at least a portion of the means for interrupting the first means for feeding power.

Abstract: A variable pressure control switch for a battery charging circuit is provided which includes a housing that receives a first member. A chamber is provided in the first member and a diaphragm extends across the chamber to divide the chamber into first and second portions. A first passage communicates with the chamber first portion and extends through the first member and is adapted to be connected with the interior of the battery to be charged so that the interior pressure of the battery is applied to the diaphragm. A second passage is provided in the first member which communicates with the chamber second portion and a piston is slidably received in the second passage. The piston is movable by the diaphragm between a first and a second position. Variable force biasing means engages the piston to prevent movement of the piston to the second position until a preset pressure has been exceeded.

Abstract: A compact AC-DC motor comprising a housing having a center section and respective end bells, each having a recess therein. A stator is received in the housing and extends into the recess in one end bell and a magnetic pole piece is similarly received in the housing and extends into the recess in the other end bell. Rotatably supported in the end bells is a shaft which mounts a rotor which cooperates with the stator, and an armature winding in juxtaposition to the rotor which cooperates with the pole piece. Additionally, a brush holder is affixed to the end of the pole piece whereby the construction provides a highly efficient motor which occupies a minimum volume of space.

Abstract: A viewfinder assembly for a camera having a door for access to the interior wherein the viewfinder, when properly positioned to permit pictures to be taken, blocks the door. The assembly comprises a support barrel mounted on a camera lens and a main body section adapted to support optical elements therein. An eyepiece is at one end of the main body section and extends outwardly therefrom. The invention includes mounting means for rotatably mounting the main body section on the support barrel to permit rotation of the viewfinder assembly to a position wherein the door is no longer blocked.