Abstract: Within a single pack tape cartridge, a bearing szrface is integrated on the cartridge case to preclude segments of the tape pack from telescoping into clearance space and thereby a retaining ring is eliminated from the tape cartridge assembly.

Abstract: Within a switching network of the type wherein at least one GTO device is rendered conductive or non-conductive to control the flow of current through a load, current is drawn from the gate of the GTO device and a shunt path is connected across the main conduction path of the GTO device simultaneously in response to a turn-off signal.

Abstract: Within current scaling circuitry having bipolar transistors of the same conductivity type disposed in principal master and slave paths, the negative feedback current gain around the principal master path transistor is regulated in direct proportion with the level of a current source that is independent from both of the principal master and slave paths, to substantially achieve tracking between the level of the current source and the levels of current flow through the principal master and slave paths.

Abstract: Within a relaxation oscillator of the type having a capacitor that is recurrently charged from a current source and then discharged through a silicon controlled rectifier upon reaching a threshold voltage thereacross, a switch is disposed to interrupt current flow between the current source and the capacitor whenever the SCR is conductive.

Abstract: Power consumption is substantially reduced and constant frequency is substantially derived without regulating the supply voltage for an oscillator circuit of the type wherein a capacitor is recurrently charged to a threshold voltage from the supply voltage and is then discharged through a gate turn-off (GTO) device. A reference voltage level proportional to the supply voltage is applied at the control electrode of the GTO device and positive current is applied at that control electrode when the differential between the charge voltage level and the reference voltage level reaches a positive trigger level, while negative current is applied thereat when that differential reaches a negative trigger level.

Abstract: Within an oscillator circuit of the type wherein positive or negative current is recurrently directed to the gate of a GTO device when the charge voltage levels across first and second capacitors respectively reach trigger levels, voltage sensing circuitry is incorporated to insure that the capacitors are charged during independent periods of time so that the duration of each portion in the frequency cycles is separately controllable.

Abstract: In a relaxation oscillator where the oscillation frequency is proportional to the charge rate of a capacitor, independent current sources are connected through separate switches to change the charge rate of the capacitor and thus the oscillation frequency. Each switch is controlled by signals from a separate detector of a condition which requires that the oscillation frequency be changed. An oscillation frequency increase between the standby and alarm modes of a smoke detector is accomplished in one disclosed embodiment and duty cycle means for controlling the operative period of the alarm indicator during each cycle of the increased oscillator frequency is disclosed in a more particular embodiment.

Abstract: An improved intermittent drive for a motion picture film projector having a film gate, condenser lens, light source and shutter means is provided by a relatively large sprocket wheel having forty sprocket teeth with 12 to 14 teeth engaging the film at the sprocket holes. This sprocket wheel is driven by a servo motor capable of rapid start and stop and high-speed motion under electronic control. The sprocket wheel supports the film between the film gate aperture (light gate) and the condenser lens. The sprocket wheel is of sufficiently large diameter so as to provide a circumferential curvature that does not appreciably change the vertical plane of a single frame of film thereon.

Abstract: In a drive circuit having output current passing through at least one bipolar transistor, the rise and fall times of the output current are predetermined by controlling the rate of current change in the master path of a current mirror amplifier which has a separate slave path connected to supply base current for each bipolar transistor. The drain-source channel of an MOS transistor is connected to selectively supply current flow through the master path of the current mirror amplifier in one embodiment of the rate control means and the gate of the MOS transistor is connected in parallel with a capacitor to the output of a CMOS inverter to which control signals are applied.

Abstract: The conductive period of a thyristor is controlled during each half cycle of an AC source to regulate the RMS voltage across a load at substantially a constant level as the AC source voltage fluctuates widely. A signal proportional to the voltage variation in the AC source is derived by monitoring that voltage and comparing it with a reference voltage. Conduction through the thyristor during each half cycle of the AC source is then delayed for a period of time in proportion to this signal so that the period of conductivity becomes inversely proportional thereto.

Abstract: Gate-turn-off silicon controlled rectifiers (GTO's) are selectively rendered conductive to control the direction of rotation of a bi-directional motor. To this end a digital logic network is responsive to either one or both of a pair of remotely located switches being operated to either a first or a second condition, for controlling a transistorized gate signal generating network to apply an operating voltage to the gate electrode of the appropriate one(s) of the GTO's. The gate signal generating network includes circuitry for grounding the gates of the GTO's, turning them off if on and thereby inhibiting operation of the motor, whenever either of two operating conditions obtains.

Abstract: A D-C converter obtains high voltage by peak-to-peak rectification of alternating potentials supplied at the secondary of a step-up transformer. The primary winding of the transformer is tuned with series capacitance and driven from the output circuit of a pulse amplifier providing pulses with a repetition rate equal to, or an integral submultiple of, the resonant frequency of the tuned transformer primary. The pulse amplifier is made to offer a low source-impedance so that the Q of the tuned primary is large enough that a substantially sinusoidal voltage with peak-to-peak value several times as large as the amplitude of the pulses supplied by the pulse amplifier appears across the primary. This desirably permits the step-up ratio of the transformer to be reduced.

Abstract: In one embodiment, the amount of power delivered to a load depends upon the length of time a touch switch is actuated or on the number of times it is actuated. In a second embodiment, the power delivered to a load starts at one level and smoothly changes to a second level. Both embodiments include a zero-crossover detector, an a.c. operated load, and a circuit responsive both to zero-crossover pulses and to a circuit actuated by the touch switch for controlling the portion during each half period of the a.c. during which power is applied to the load.

Abstract: The base-emitter junction of a bipolar transistor is first forward biased to place the transistor in a state of conduction and the forward bias is then removed. A discharge path is provided for the base-emitter capacitance of the transistor, this path including a source of reverse bias voltage for the base-emitter junction. A sensing circuit indicates when the base-emitter capacitance has discharged through the path sufficiently to permit the base-emitter junction to become reverse biased, which in turn indicates that the transistor has cutoff.

Abstract: The photoelectric detector output in the spectrophotometer is amplified with separate stages of fixed and variable gain to derive background absorption compensation when the intensity of the continuous spectrum emitting radiation source therein varies from optimum levels. Where a reference output of the photoelectric detector is desirable for the background absorption compensation, a dark interval of the photoelectric detector and an output channel are provided for each gain stage.

Abstract: A graphite furnace for flameless atomic absorption spectroscopy comprising a graphite sample tube with a sample port at the mid-point of its length. Electrodes supportively contact the tube ends and pass electrical heating current through the tube. The electrodes have hollow cylindrical portions which laterally envelope the tube over substantially its entire length, one of the electrodes being longer than the other and containing a radial bore in registration with the sample port. The cylindrical portions of the electrodes are disposed with complementary-shaped recesses in cooling jackets which encase all but the mid-length regions of the electrode cylindrical portions. The electrodes fit readily in the cooling jackets at room temperature due to differential expansion of these members. The sample tube, electrodes, cooling jackets and associated structure are mounted on a base with provisions for adjustment of the tube about various orthogonal axes.

Abstract: Sample preparation apparatus for forming a thin layer of diluted blood specimen on a substrate by centrifugal force includes a sample probe having coaxial blood and diluent conduits coupled to respective reversibly-drivable peristaltic pumps having forward operation intakes connected to a diluent supply. A one-way clutch limits the diluent pump to forward operation and the pumps are geared to produce a blood-to-diluent displacement ratio of 2:1. A substrate holder is mounted on a carriage for selective insertion into and removal from a sealed centrifuge chamber in which it is spun at a high angular rate by a drive motor. Means are provided to form a curtain of flowing liquid within the chamber surrounding the spinning substrate to collect spun-off blood particles and aerosol. The liquid forming the curtain is drained by an exhaust pump which operates after spinning has ceased so as to create a partial vacuum for draining off residual aerosol prior to unsealing the centrifuge chamber.

Abstract: A highly stable and sensitive photometric apparatus is obtained by combining a sensitive, stable, unchopped, dual-beam optical photometer with an accurate electronic sensing circuit. The circuit includes PIN silicon diode detectors on which the two beams of the photometer are imaged. One beam is a reference to detect light source variations and the other a signal beam passing through the sample cell of the photometer. The PIN diode outputs are inputs to parametric amplifiers. The amplifier outputs are then provided to log taking means which take the logarithms of the two signals and then take the difference of the two logarithms to provide a final output proportional to absorbtion in the cell.

Abstract: Apparatus for illuminating and enhancing the visibility of a region in a transparent medium containing light scattering particles, such as fog or smoke in air or particles in water, comprises a source of a beam of illumination that is narrow in one plane and a viewing collimator for narrowly restricting the observer's instantaneous field of view in a single plane having the same general vertical, horizontal or other orientation as the beam of illumination. The viewing collimator and the illuminating source are spaced apart and mounted for relative movement of the collimated instantaneous field of view and the illuminating beam to cause them to intersect in a region in front of and distant from the observer and for the region of their intersection to scan a larger region.

Abstract: An improved apparatus for obtaining X, Y and .theta. relative motion of an object in which four links pivotally connected in a parallelogram with the object forming one link thereof is used, with means provided to rotate a first of the links while holding stationary the adjacent link to produce a Y motion, and means to rotate one of said links to thereby rotate the arrangement, in each case, the motion being accomplished with negligible cross-coupling and in a manner which permits fine adjustments of the order of a micron with no lost motion.