Switching Circuitry Research Articles

Vapor jet control of space vehicles

This paper describes a reaction jet attitude control technique which affords significant advantages in terms of accuracy, reliability, fuel economy and operational flexibility. These advantages are realized by the use, in combination, of low-thrust vapor jets and time-dependent on-off switching circuits. An accuracy potential comparable to inertia wheel control is thus provided, while the proverbial wheel problems of speed saturation, bearing life, threshold nonlinearities, gyroscopic coupling and vibration excitation are avoided. Very-low thrust magnitudes are attained by simply opening a small orifice to allow fuel to vaporize into the surrounding vacuum. Fuel storage, pressurization, circulation and mixing requirements are thus minimized. By augmenting conventional on-off valve switching circuitry with electronic networks that generate thrust pulses of small but constant time duration, vehicle angular rate can be controlled to a very-low threshold. This minimizes fuel consumption and valve cycling frequency. The capabilities and limitations of this design approach were substantiated by an analog computer program incorporating breadboard switching circuits, and by vacuum chamber testing of critical components. These technique and component developments are applicable to such space missions as astronomical observation, earth reconnaissance and stellar navigation. Design guides are presented for synthesizing a reaction jet system to meet any particular set of performance specifications.

An improved detached-contact-type of schematic circuit drawing

THE ever-increasing complexity of telephone and telegraph switching circuitry in the Bell System reached a stage, about 10 years ago, where many of the conventional type of schematic circuit drawings presented difficulties in training of personnel and maintenance. It then became necessary, for the more complex circuits, to prepare and maintain a separate series of drawings especially streamlined for training purposes and for aiding maintenance. However, the preparation of two sets of drawings for these cases and the necessity for keeping them in step as improvements and changes were added was costly. To meet this problem the new type of circuit drawing described in this paper was developed. It is designed for easy understanding and incorporates in a single package the basic circuit information required for manufacture, installation, training, maintenance, and engineering analysis.

Improved detached-contact circuit drawing

THE ever-increasing complexity of telephone and telegraph switching circuitry in the Bell System had reached a stage about 10 years ago, where many of the conventional type of schematic circuit drawings presented difficulties in training of personnel and maintenance. It then became necessary, particularly for the more complex circuits, to prepare and maintain a separate series of drawings—especially streamlined for training purposes and for aiding maintenance. However, the preparation of two sets of drawings for these cases and keeping them in step as improvements and changes were added was costly.