Abstract: A motion picture apparatus is provided which comprises a rotary disc shutter having a shutter sector and actuated by an electric drive device. A claw mechanism is controlled by the electric drive device and provides for transport of a film. An electromagnetic solenoid provides for stopping the film in position. A plunger for the solenoid is provided for disengaging the claw transport mechanism after a frame transport phase upon generation of an appropriate signal. A position signal generator provides a shutter position signal depending on the position of the shutter sector and a marking signal generator provides a signal depending on the detection of a marking placed on the film. The position signal generator is connected to a first input of an AND gate and the marking signal generator is connected to a second input of the AND gate. The output of the AND gate is connected to the solenoid.The apparatus and a corresponding method provide for stopping a film without interference in proper position.

Abstract: A motion picture apparatus and preferably a motion picture projector. A rotary disc shutter is actuated by an electric drive and comprises a shutter sector. A claw mechanism controlled by the electric drive provides for transport of a film and the motion of the film is controlled by a solenoid having associated a solenoid plunger suitable for disengaging the claw transport mechanism after a frame transport phase. A position pulse generator provides a shutter position pulse depending on the position of the shutter sector. An output memory element connected to the electromagnet solenoid controls the energization of the electromagnet and in turn is connected to a switch and to the position pulse generator. Preferably additional memories are provided for performing functions such as controlling the advance and the reverse motion or providing for a timer or individual frame operation.

Abstract: An electric motor which can drive the objective of a slide projector or which can adjust the blade or blades of a diaphragm receives signals from the output of an operational amplifier which receives first and second signals from a photosensitive transducer and a differentiating capacitor. The (second) signals from the capacitor are modified (first) signals from the transducer, and the combined intensity of first and second signals is such that the signals at the output of the amplifier reach a value which they would normally reach only when the component has already assumed a predetermined position before the motor can complete the movement of the component to such position.

Abstract: A switchboard booth structure having a unique arrangement of exteriorly accessible service and control devices and interiorly accessible switch devices for controlling low voltage elements of electrical apparatus, particularly metallurgic electric furnaces is disclosed herein.

Abstract: A sound recording head includes an induction coil. A feedback resistor is connected in series with the induction coil between the input and output of an operational amplifier to form the feedback branch of the amplifier. A load resistor is connected to the junction between the feedback resistor and the induction coil. An audio-frequency audio signal and also a higher-frequency magnetic biasing signal are applied to the operational amplifier input. The open-loop gain of the operational amplifier is at least one order of magnitude greater than the gain of the amplifier with the aforementioned feedback branch connected thereto. The resistance of the feedback resistor is at least one order of magnitude greater than the impedance of the induction coil at the frequency of the magnetic biasing signal. The resistance of the load resistor is at least one order of magnitude smaller than the impedance of the induction coil at the frequency of the magnetic biasing signal.