Selective fuser apparatus and control therefor for use in xerographic reproducing apparatus. In the xerographic reproducing apparatus contemplated, documents are scanned and selectively reproduced in accordance with coded information carried thereby. The coded information is utilized for generating print or select signals when a particular document is to be reproduced and when a document is not to be reproduced a non-print or non-select signal is generated. A temperature sensor is provided for s...

A feedback switch mechanism for a manually operated, nonmechanical switch for keyboards, and the like, is provided through use of a spring-loaded cam follower carrier that has a cam follower which follows a cam surface that is integrally formed on the plunger of the switch. Upon depression of the plunger, a force build-up and release occurs due to the action of a bias spring on the cam follower carrier which simulates the actuation of a mechanical switch so that the operator is assured that a da...

This relates to an apparatus for obtaining a specific antenna current or voltage waveshape at an antenna. A reference network, which includes a low level lumped element model of the antenna and the transmitter output network, produces drive signals when impulsed. The first of these signals corresponds to a voltage having the desired antenna current waveshape. The second is a voltage having a waveshape which must be produced across the input terminals of the transmitter output network in order th...

A system for suppressing positive feedback in acoustical-electrical devices having acoustic or electric feedback paths or a combination of both. Electrical signals from a microphone are transmitted through a sampling switch to a signal storage device. The transfer rate and duration are controlled by a pulse generator driven by an oscillator to time domain process the signals. The discrete signals output from the signal storage device are smoothed by a low pass filter and used to drive follow on ...

Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed f...

A hydrostatic servomechanism adapted for controlling the direction of vehicles and selfpropelled machines. The servomechanism has a power circuit including a servopump, a distributor with reset mechanism, and a servomotor and a control circuit with a measuring pump connected through the control branches to the reset mechanism of the distributor and actuated by means of a command element, for example a vehicle steering wheel. The invention provides a simple reliable servomechanism with an artific...

An electroencephalographic instrument for the bio-feedback of human brain waves within the Alpha and Theta frequency bands utilizes an adjustable headband electrode and a clip-on electrode as its pick-ups and earphones which provide an audible signal to the user. The circuitry of the instrument includes an active filter comprising a band-pass network and an operational amplifier, and an oscillator whose frequency is modulated by the active filter.

A test board is disclosed which has a flat surface with a number of holes therein that provide a response feedback when a student, using a stylus, attempts to punch openings through answer zones on an instructional sheet overlying the surface. The test board is a plate member, preferably of unitary construction, formed with a pattern of upwardly projecting, tapered support components that presents the surface, such components defining the boundaries of a number of discrete, recessed areas repres...

An improvement in a system for actuating a pair of fluid-pressure operated devices including a first modulator in series with a first accumulator connected in circuit with a first one of the devices, a second modulator in series with a second accumulator connected in circuit with a second one of the devices, each of the modulators including a variable volume chamber for receiving pressurized fluid, each of the accumulators including piston means, with each accumulator being charged from the pres...

A feedback system provides control for an actuator in a range of error signals wherein deadband is otherwise frequently provided to reduce noise content of a parameter controlled by the actuator. A signal indicative of the magnitude of the controlled parameter is compared with a setpoint for the controlled parameter to derive an error signal having a magnitude and polarity equal to the difference between the parameter and the setpoint. For error signals within assigned limits, a control signal f...