the potentiometer handbook - bourns potentiometer handbook - bourns
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Welcome to the on-line version of the The Potentiometer Handbook originally published in hard cover by McGraw-Hill Book Company.
We have made only a few changes to the original in the area of Industry Standards and Military Specifications.
The technology represented in this handbook has had no significant change in years andremains as viable today as it was when this volume was published.
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For more information you can also go to the Bourns web site at www.bourns.com , select applications information under the About Us button then selecting the Library button.
You may also want to review applciaction information from the Trimmer Primer by using link below: http://www.bourns.com/pdfs/trmrpmr.pdf
Copyright 1975, 2008
Adobe and Adobe Reader are registered trade-marks of Adobe Systems Incorporated.
PHOTOGRAPHS CONTRIBUTED BY:
AMI MEDICAL ELECTRONICS
BIDDLE CO., JAMES G.
CENTRAL SCIENTIFIC CO.
DUNCAN ELECTRONICS, INC.
GENERAL RADIO CO.
INTERSTATE ELECTRONICS CORP.
KRAFr SYSTEMS, INC.
LEEDS AND NORTHRUP
POWER DESIGNS, INC.
SPACE-AGE CONTROL, INC.
WEYER HAUSER CO.
WILLI STUDER, SWITZERLAND
REPRINTED BY PERMISSION OF THE VARIABLE RESISTIVE COMPONENTS INSTITUTE
USERS' GUIDE TO
CARL DAVID TODD, P.E. CONSULTING ENGINEER
W. T. HARDISON Product Marketing Specialist
Trimpot Products Division Bourns, Inc.
W. E. GALVAN Applications Engineer
Trimpot Products Division Bourns, Inc.
lHcGRAW-HILL BOOK COIHPANY New York St. Louis Slln Francisco Auckland Diis~eldotf J()I,,"'nc~buty
New Delhi Kual" Lumpur
Sydney Paris Tokyo
London Mexico Munlteal
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Library o f Congress Cataloging in Pu blication Data
Todd, Carl Dayid. The potentiometer handbook.
I. Potentiometer-Handbooks, manuals, etc. 2. Electric resistors- Handbooks, manuals, etc. I. Bourns, inc. II. T itle. TK7872. P6T63 621.37'43 75-20010 ISBN 0-07-006690-6
Copyright ]975 by Bourns, Inc. All rights reserved. Printed in the Uni ted States of America. No part o f this publication may be reproduced, stored in a retrieyal system, or transmitted, in any form or by any means, electronic, mechanical, photocopying. recording, or OIherwise, without the prior written permission o f the publisher.
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The inform31ion conveyed III Ihl. book has been carefully reviewed and believed 10 M aCCurale and r.ll~blc; however, "0 re,poIIsibiU'.y i. assumed for Ihe opcrabilny of any circuit di.sram or inaccuracie, In calcul alions or st.t.menU. Furlher. nOlhin& h ...,in conveys 10 the purcha.$l:f a license under the patent rllhlll of a ny individual or organluotion ,elal;ng 10 the .ubj1 malin dcs
PREFACE In the decades following the advent of the transistor, electronic technology experienced explosive growth. Thousands of new circuits were generated annually. The demand for variable resistive components to adjust, regulate or control these circuits shared in the expansion.
T he number of applications [or variable resistive components has increased significantly. This is contrary to predictions of a few soothsayers of the '60's who interpreted the miniaturizing effects of integrated circuit technology as a threat to these components. Potentiometers will continue to enjoy strong growth into the foreseeable future . This optimistic forecast is particularly true in consumer and industrial applications where potentiometers provide the cost-effective solution in trimming applications and the ever-present necessity of control for man-machine interface.
Many articles, booklets, and standards have been published on potentiometers; yet, there is no single, comprehensive source of practical information on these w idely used electronic components. It is this void that The Potentiometer Handbook is intended to 611.
One objective of this handbook is to improve communications between po-tentiometer manufllcturcrs and users. To this end, explanlltions of performance specifications and test methods, arc included. Common understanding of ter-minology i~ the key to communication . For this reason, lesser known as well liS preferred terminology life included, with emphasis on the latter. Hopefully, this will create the base for easy. accurule dialogue. Over 230 photos. graphs and drawings illustru\e and clarify important concepts.
This book assumes the rellder has a knowledge of electronic and mathematical fundmentals. However, basic definitions and concepts can be understood by nontechnical personnel. The major portion of this text is written for systems and circuit designers, component engineers, and technicians as a pructical aid in design and selection. I t is an important reference lind working hllndbook oriented towards practical application idells and problem solving. For the student, it introduces the basic component, its most common uses, and basic terminology.
Enough objective product design and manufacturing process information is in the lex! to allow the user to understand basic differences in materials, designs. and processes that arc availllble. This will sharpen his judgment on 'cost-versus-performance' decisions. Thus, he can avoid over-specifying prodUct require-ments and take advantage of the cost-effectiveness of variable resistive devices.
Also included arc hints and design ideas compiled over the years. As with any discipline, these guidelines are often discovered or developed through unfortu-nate experience or misapplication. Most chllpters conclude with a summary of key points for quick review and reference.
Speaking o( misapplication, Chapter 9, To Kill a Potentiometer, is a tongue-in-check potpourri of devious methods to wipe out a potentiometer. This is a lighthearted approach to occasional serious problems caused by human frailties . Not much more need be said except he/ore all else fails , read the book, or at least tbis chapter!
Suggestions from readers on improving this volume arc encouraged lind wcl-corned. Subsequent editions will include the results of these critiques together with advanced material relating to Ihe state-of-art in potentiometer design and application.
W. T. Hardison
xi List of illustrations
1 Chapter ONE - INTRODUCTION TO POTENTIOMETERS Historical evolution and milestones of variable resistive devices from mid 19th century to present. Development of the basic concepts of resistive element and moveable cont
51 Chapter THREE - APPLICATION FUNDAMENTALS Presentation of the fundam(!ntal operational modes possible when applying the potentiometer in electrical circuits. Basic explanations assume ideal , theoretical conditions. Significance and effect of the parameters in Chapler Two. Subjects include error compensation, adjustment range control, data input and offset capability.
51 VARIABLE VOLTAGE DIVIDER MODE
62 VARIABLE CURRENT RHEOSTAT MODE
71 DATA INPUT
74 APPLICATION FUNDAMENTALS SUMMARY CHART
77 Chapter FOUR - APPLICATION AS A CIRCUIT ADJUSTMENT DEVICE
The potentiometer as a circuit component without regard to total system. Analog and digital ap-plications with transistors, diodes, fixed resistors, capacitors, integrated circuits and instruments.
78 POTENTIOMETER OR FIXED RESISTORS?
78 POWER SU PPLY APPLICATIONS
81 OPERATIONAL AMPLIFIER APPLICATIONS
87 DIG ITAL C IRCUITS
91 MISCELLANEOUS APPLICATIONS
.7 Chapter FIVE - APPLICA TION AS A CONTROL DEVICE The potentiometer as a system component. Application in interesting systems, e.g. oscilloscopes, power supplies, function generators, meters and recorders.
98 BASICS OF CONTROL
101 INSTRUMENT CONTROLS
104 AUDIO CONTROLS
106 MISCELLANEOUS CONT ROLS
115 Chapter SIX - APPLICATION AS A PRECISION DEVICE The potentiometer in system s requiring high accuracy. Importance of electro-mechanical parameters in precision applicat ions. Applications in systems and circuits where accuracy is the most important consideration.
115 OPERATIONAL CHARACTER ISTICS
115 POWER RATING
118 FREQUENCY CHARACTER ISTICS
120 LI NEA R FU NCTION S
121 NONLINEAR fUNCTIONS
126 VOLTAGE TRACKI NG ERROR
127 CLOSED LOOP FUNCTIONS
127 MECHAN ICAL PARAMETERS
130 NQNWfREWOUND PR ECISION POTENTIOMETERS
133 LINEA R DISP LACEMENT TRANSDUCER
[33 LQWTORQUE POTENTIOMETERS
134 COA RSE/ PINE DUAL CONTROL
135 POSITION INDICATION TRANSMISSION
136 THE X-22A , V I STQL AIRCRAFT
137 A DENDROMETER
138 SORTI NG BRJDGE