Newnes Electronics Engineers Pocket Book PDF
Preview Newnes Electronics Engineers Pocket Book
Newnes Electronics Engineer ’s Pocket Book Keith Brindley | N E W N E 5 Newnes An imprint of Butterworth-Heinemann Ltd Linacre House, Jordan Hill, Oxford 0X2 8DP A member of the Reed Elsevier group OXFORD LONDON BOSTON MUNICH NEW DELHI SINGAPORE SYDNEY TOKYO TORONTO WELLINGTON First published 1993 © Butterworth-Heinemann Ltd 1993 All rights reserved. No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1P 9HE. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 0 7506 0937 1 Typeset and produced by Co-publications, Loughborough Printed in England by Clays Ltd, St Ives pic Preface This book is a revision of two books: Newnes Radio and Electronics Engineer’s Pocket Book and Newnes Electronics Pocket Book. The first, Newnes Radio and Electronics Engineer’s Pocket Book, was initially published in 1940. It has been my pleasure in editing and revising it since the 16th edition in 1985, till the 18th edition in 1989. Andrew Parr was revising editor of the 5th edition of Newnes Electronics Pocket Book, a book whose first edition was published in 1963. Thanks to him and all the other editors and revisers who have been involved with the two books over the years. Quite a pedigree — I’m sure you’ll agree. Electronics reference books are, generally, quite specific in nature; often covering such narrow and detailed aspects that they are of use to only a minority. Those few books which cover more than this tend not to allow easy reference to specific details, and are expensive. My intention in revising and incorporating both books into this single book is to cater for the needs of most people with interests in electronics related areas. While doing this, I hope I have succeeded in keeping it easy to locate required information — at an affordable price. My main criterion in choosing what to incorporate from both books, and what to discard, is, “What do I look up?” I try to include, therefore, anything of relevance to electronics referred to in literature — tables, conversion factors, symbols and so on. Anything for which a calculator or computer is better used is not included. Keith Brindley 2 Electron physics All matter consists of molecules, which are defined as the smallest portion of a substance capable of independent existence and having the properties of the substance. Studies by Dalton and others in the early part of the nineteenth century showed that molecules consist of groupings of various types of atoms. These atoms relate to the basic elements of which all matter is constructed. There are over 100 elements, from hydrogen (the lightest) to uranium (one of the heaviest). A molecule of table salt, for example, consists of one atom of sodium and one atom of chlorine. A molecule of copper sulphate consists of one atom of copper, one atom of sulphur and four atoms of oxygen. Atoms are far too small to be observed directly with a micro scope, but their existence can be inferred by experiments. Atomic structure Experimental work on gas discharge effects suggested that an atom is not a single entity but is itself composed of smaller particles. These were termed elementary particles. The atom appeared as a small solar system with a heavy nucleus composed of positive particles and neutral particles. These were named protons and neutrons. Around this nucleus, clouds of negatively charged particles, called electrons, circle. As an atom is electrically neutral, the negative charge carried by the electrons must be equal in magnitude (but opposite in sign) to the positive charge carried by the protons. Experiments with electrostatic charges show that unlike charges attract, so it can be considered that electrostatic forces hold an atom together. The difference between various atoms is therefore determined by their composition. A hydrogen atom consists of one proton and one electron; a helium atom of two protons, two neutrons and two electrons. (a) (b) Atomic structure: (a) hydrogen atom; (b) helium atom 2 Electron physics All matter consists of molecules, which are defined as the smallest portion of a substance capable of independent existence and having the properties of the substance. Studies by Dalton and others in the early part of the nineteenth century showed that molecules consist of groupings of various types of atoms. These atoms relate to the basic elements of which all matter is constructed. There are over 100 elements, from hydrogen (the lightest) to uranium (one of the heaviest). A molecule of table salt, for example, consists of one atom of sodium and one atom of chlorine. A molecule of copper sulphate consists of one atom of copper, one atom of sulphur and four atoms of oxygen. Atoms are far too small to be observed directly with a micro scope, but their existence can be inferred by experiments. Atomic structure Experimental work on gas discharge effects suggested that an atom is not a single entity but is itself composed of smaller particles. These were termed elementary particles. The atom appeared as a small solar system with a heavy nucleus composed of positive particles and neutral particles. These were named protons and neutrons. Around this nucleus, clouds of negatively charged particles, called electrons, circle. As an atom is electrically neutral, the negative charge carried by the electrons must be equal in magnitude (but opposite in sign) to the positive charge carried by the protons. Experiments with electrostatic charges show that unlike charges attract, so it can be considered that electrostatic forces hold an atom together. The difference between various atoms is therefore determined by their composition. A hydrogen atom consists of one proton and one electron; a helium atom of two protons, two neutrons and two electrons. (a) (b) Atomic structure: (a) hydrogen atom; (b) helium atom 3 Work by Bohr and others in the early part of the present century demonstrated that the electron orbits are arranged in shells, and that each shell has a defined maximum number of electrons it can contain. The first shell can contain two electrons, the second eight electrons. The number in each shell is given by: 2n2, where n = 1, 2, 3 and so on. Chemical reaction and electrical effects are all concerned with the behaviour of electrons in the outer shell of any particular atom. If a shell is full, for example, the atom is unable to react with any other atom and is, in fact, one of the inert gases such as helium. Electrons and electric currents If there are few electrons in the outermost shell, the forces binding them to the nucleus are weak. Thermal effects easily detach these electrons, leaving a positively charged atom. These detached electrons drift around inside the substance until they meet another positively charged atom, at which they become captured again. The process of free electron production and recapture is going on continuously, and the substance can be considered as being permeated with a negatively charged gas. If an electrical potential is now applied across the substance, the free electrons will start to accelerate towards the positive connection. As they move they will collide with atoms in the substance, releasing energy which we observe as heat. The net effect is a drift of electrons at a roughly constant speed towards the positive connection. The motion of electrons is an electric current. As electrons are removed by the electrical potential source at the positive connection, electrons are being injected at the negative connection. The potential can be considered as a form of electron ‘pump’. This model explains many observed effects. If the magnitude of electrical potential increases, the electrons accelerate faster and their mean velocity is higher i.e. the current increases. The collisions between electrons and atoms transfer energy to the atoms which manifests itself as heat. This effect is known as Joule heating. Materials such as these are termed ohmic conductors, as they obey the well-known Ohm’s law; V — = a constant (R) / The constant is the resistance of the material. If V is in volts, and I is in amps, the constant (R) is in ohms. Not all electrical conduction is ohmic; heating and other effects cause some materials to have complex V/I relationships. If electrons in the outer orbit are tightly bound, negligible amounts of free electrons are formed. If an electric potential is applied, very few electrons move and the current is small. Sub stances with these characteristics are called insulators. 3 Work by Bohr and others in the early part of the present century demonstrated that the electron orbits are arranged in shells, and that each shell has a defined maximum number of electrons it can contain. The first shell can contain two electrons, the second eight electrons. The number in each shell is given by: 2n2, where n = 1, 2, 3 and so on. Chemical reaction and electrical effects are all concerned with the behaviour of electrons in the outer shell of any particular atom. If a shell is full, for example, the atom is unable to react with any other atom and is, in fact, one of the inert gases such as helium. Electrons and electric currents If there are few electrons in the outermost shell, the forces binding them to the nucleus are weak. Thermal effects easily detach these electrons, leaving a positively charged atom. These detached electrons drift around inside the substance until they meet another positively charged atom, at which they become captured again. The process of free electron production and recapture is going on continuously, and the substance can be considered as being permeated with a negatively charged gas. If an electrical potential is now applied across the substance, the free electrons will start to accelerate towards the positive connection. As they move they will collide with atoms in the substance, releasing energy which we observe as heat. The net effect is a drift of electrons at a roughly constant speed towards the positive connection. The motion of electrons is an electric current. As electrons are removed by the electrical potential source at the positive connection, electrons are being injected at the negative connection. The potential can be considered as a form of electron ‘pump’. This model explains many observed effects. If the magnitude of electrical potential increases, the electrons accelerate faster and their mean velocity is higher i.e. the current increases. The collisions between electrons and atoms transfer energy to the atoms which manifests itself as heat. This effect is known as Joule heating. Materials such as these are termed ohmic conductors, as they obey the well-known Ohm’s law; V — = a constant (R) / The constant is the resistance of the material. If V is in volts, and I is in amps, the constant (R) is in ohms. Not all electrical conduction is ohmic; heating and other effects cause some materials to have complex V/I relationships. If electrons in the outer orbit are tightly bound, negligible amounts of free electrons are formed. If an electric potential is applied, very few electrons move and the current is small. Sub stances with these characteristics are called insulators. 4 Motion of electron in an electric field If an electric potential is applied between two plates in a vacuum, and an electron in introduced, the electron experiences an attractive force to the positive plate. +ve nF Electron attracted Direction of to positive plate— Θ electric field -ve- Electric field between parallel plates This force causes the electron to accelerate towards the positive plate in a straight line. It suffers no collisions because the area between the plates is in vacuo. This effect is used in thermionic valves. If the electron is given some motion and the electron field is applied perpendicular to the motion, interesting effects occur. In the system below, a beam of electrons is emitted from a device called an electron gun. These electrons are moving in the x direction. As they emerge they pass between two plates which have a potential applied across them in the y direction. As the electrons pass between the plates they are accelerated in the y direction, as explained before, but their velocity in the x direction is unaltered. The electron beam is thus deflected as shown. By varying the potential applied to the plates, the angle of deflection can be controlled. This effect is the basis of the cathode ray oscilloscope. Electrostatic deflection of electron beam 4 Motion of an electron in a magnetic field A moving electron is effectively an electric current. Experiments with electric motors demonstrate that magnetic fields exert a force on wires carrying current, and similar effects may be expected to occur with moving electrons. Direction of the force can be predicted from Fleming’s left hand rule. An electron experiences a force when moving perpendicular to a magnetic field. This force is at right angles to both the field and the direction of the electron’s motion. It follows that electrons moving parallel to a magnetic field are unaffected. Electrons movin A ' ' Parallel magnetic parallel to field field unaffected > ▼ < Electrons with movement aEclerocstrso nfise ldm otrvai<i c ) at angle to field trace a circular path ) out a spiral at right angles to paper Motion of electrons in a magnetic field There is one important difference between the motion of an electron in a magnetic field and its motion in an electric field. In an electric field the force is a fixed direction, whereas in a magnetic field the force is always at right angles to the electron’s motion. It follows that an electron injected into a suitable magnetic field can be made to spiral along the field axis. This effect is used in magnetic focusing coils in a television tube. Structure of matter Matter can exist in three states; solid, liquid and gaseous. In the liquid and gaseous states molecules can move around freely. In the solid state, however, molecules are fixed and can only vibrate about their mean positions. These vibrations we interpret as heat. There are several substances which are observed to form crystals; table salt and copper sulphate are two common examples. Crystals form because the atoms arrange themselves into a geometrical pattern, and this pattern continues however large the crystal. At the atomic level, however, atoms in most substances are arranged in a crystalline pattern. A representation of the crystalline structure of germanium is shown, and the regular pattern is obvious. 4 Motion of an electron in a magnetic field A moving electron is effectively an electric current. Experiments with electric motors demonstrate that magnetic fields exert a force on wires carrying current, and similar effects may be expected to occur with moving electrons. Direction of the force can be predicted from Fleming’s left hand rule. An electron experiences a force when moving perpendicular to a magnetic field. This force is at right angles to both the field and the direction of the electron’s motion. It follows that electrons moving parallel to a magnetic field are unaffected. Electrons movin A ' ' Parallel magnetic parallel to field field unaffected > ▼ < Electrons with movement aEclerocstrso nfise ldm otrvai<i c ) at angle to field trace a circular path ) out a spiral at right angles to paper Motion of electrons in a magnetic field There is one important difference between the motion of an electron in a magnetic field and its motion in an electric field. In an electric field the force is a fixed direction, whereas in a magnetic field the force is always at right angles to the electron’s motion. It follows that an electron injected into a suitable magnetic field can be made to spiral along the field axis. This effect is used in magnetic focusing coils in a television tube. Structure of matter Matter can exist in three states; solid, liquid and gaseous. In the liquid and gaseous states molecules can move around freely. In the solid state, however, molecules are fixed and can only vibrate about their mean positions. These vibrations we interpret as heat. There are several substances which are observed to form crystals; table salt and copper sulphate are two common examples. Crystals form because the atoms arrange themselves into a geometrical pattern, and this pattern continues however large the crystal. At the atomic level, however, atoms in most substances are arranged in a crystalline pattern. A representation of the crystalline structure of germanium is shown, and the regular pattern is obvious.
The list of books you might like
