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General Electric Company has developed the D67D (a high speed darlington) power transistor rated at 400 Volts (sustaining) and collector currents of 100 Amps continuous (160 Amps peak). The devices are monolithic and utilize a new power package which is available in the isolated (R??JC = .4??C/W max.) and non-isolated (R??JC = .25??C/W max.) collector configurations. Some typical applications for...
A new British Post Office standard power plant has been designed to operate from a single-phase a.c. mains or standby generator input, and to provide secure d.c. power to 50 V telecommunications equipment. The plant features standby rectifier capacity, battery standby with a choice of duration, and a regulated output during battery discharge without the need for end-cell switching. A range of standard...
Multi-output dc-to-dc converters controlled by magnetic amplifiers are presented. In these power converters, the magnetic amplifiers with frequencies of 80 to 400kHz are used instead of the conventional switching transistors. The magnetic amplifier and an additional saturable core suppress the surge occurrence, and consequently these power converters can operate with the relatively low power dissipation...
A new PWM controller with simple structure is presented. This controller consists of a modified transistor-core multivibrator having a single saturable core and is capable of changing the oscillation frequency with ease by a low control voltage. Accordingly, if this controller is applied to a small DC power supply or a feedback element of the switching regulator, a considerable reduction of the number...
A ringing choke converter using a single core saturable reactor in the control circuit is described. Besides the few components, simplicity and small size usually found in self-oscillating converters, this converter features a saturable reactor protective functions for overcurrent through the main transistor switch and for magnetic saturation of the power transformer, and good isolation of output...
The success of the application of switched mode techniques to d.c. power supplies has naturally led to developments of these techniques for the generation of a.c. voltages. Recently attention has been given to the use of microprocessors to program the outputs of these function generators. A low frequency programmable function generator has particular application in the telephone industry, where there...
Current transformers present inherent advantages for driving power switching transistors over alternative driving methods. This paper presents advantages and design problems of current transformer drives in two applications: a) free running push-pull inverter b) switched mode regulator Each application is discussed with respect to: Driver circuit application Design problem analysis of 20 kHz current...
This paper deals with the specifications, characteristics, functions, and examples of applications of the Electronic Universal Load developed for use in the developement of power supply units, their testing and income inspection. The function of controlling load current by entering a BCD code permits, among other functions, automatic testing through connection to a computer. This paper gives a detailed...
Photovoltaics, as a compliment source of power for telecommunication applications, has been recently widely accepted. Photovoltaic modules consisting of silicon solar cells connected in series or parallel, provide on site, the required charging current for the batteries, thus enabling maintenance free operation and reduced storage costs for the total system. Flat plate solar panels are presently operating...
The author has been working on improved methods of conducting low voltage testing of electronic telephone switching equipment. The problems with existing techniques are discussed, together with a description of voltage reduction equipment being developed to eliminate these problems.
This paper discribes power converters used and in the research phase in NTT. Nowadays, almost all converters are semiconductor converters. Since they are efficient, small and reliable, they are used in many telecommunication systems. Recent progress in the telecommunication systems enhances the requirement for further converter development. Studies on converters have been continued to minimize size,...
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