Masters Theses

Abstract

"A stable direct current transistor amplifier is difficult to design for use at elevated temperatures. The above is true since transistor parameters and bias conditions are affected by temperature. When transistors are incorporated in direct coupled amplifier circuits, these variations in parameters and bias conditions usually result in unstable operation. It is the purpose of this thesis to investigate this problem and to design a stable direct current transistor amplifier which will operate satisfactorily at elevated temperatures.

This problem is of importance as such direct current amplifier circuits are found in airborne or missile servo systems. In such systems the weight and bulk of vacuum tubes, the power consumption, and the heat dissipation problems have focused attention upon the transistor. Unfortunately, such circuitry is subjected to extremes of operating temperature, thus prohibiting the use of transistorized circuits unless heavy air conditioning equipment is used. If means of stabilizing the transistor direct current amplifier could be found, then transistors could be used to solve a critical defense problem.

This problem was first encountered when the author was employed during the summer of 1956 at the Emerson Electric Manufacturing Company of St. Louis, Missouri. During this period a temperature study of R-C coupled transistor amplifiers was made, but when the author first attempted to test a direct coupled design at high temperature the problem became evident, as the transistors proceeded to destroy themselves in a thermal runaway. The Emerson Electric Manufacturing Company, being interested in transistor direct coupled amplifiers, agreed to provide the components for subsequent investigations to be conducted as a thesis problem at the University of Missouri, School of Mines and Metallurgy. Therefore, because of this experience of unstable circuit action at high temperatures, the author became interested in this problem.

The following review of literature and discussion of the design of a stable transistor direct current amplifier is written under the assumption that the reader is familiar with basic transistor concepts of operation and with the terminology generally used in this field. Only theoretical concepts dealing with the effects of temperature on the transistor and its associated circuitry will be included. Noise power supply stability, and any other such variables are considered to be irrelevant in this study of transistor circuits and temperature.

The thesis consists of a review of literature featuring three topics which are: (1) transistors and temperature (2) stabilization techniques, and (3) direct current transistor amplifier designs. This is followed by a description and analysis of a direct current transistor amplifier based upon the findings in the literature review. The results of temperature tests are included for this design to substantiate the use of the included ideas"--Introduction, pages 1-2.

Advisor(s)

Skitek, G. G. (Gabriel G.)

Department(s)

Electrical and Computer Engineering

Degree Name

M.S. in Electrical Engineering

Publisher

Missouri School of Mines and Metallurgy

Publication Date

1957

Pagination

ix, 103 pages

Note about bibliography

Includes bibliographical references (page 101-102).

Rights

© 1957 William Lewis Metcalf, Jr., All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Library of Congress Subject Headings

Transistor amplifiers -- Design
Electronic apparatus and appliances -- Thermal properties
Materials at high temperatures

Thesis Number

T 1150

Print OCLC #

5156902

Electronic OCLC #

933298219

Share

 
COinS