Chapter.1
Matter and Electricity
Matter and Electricity
Electricity is a physical phenomena involving positive and negative charge. When these charges are in motion they may produce heat, light and magnetism. When charges are not in motion, static electricity can manifests itself as a force such as clothes clinging to each other when they are removed from a dryer.
A simple stationary system of a single positive ion and a single negative ion (or electron) separated by large distance with respect to their size ( a meter for example) will have a E field associated with them. Along the axis connecting the two ions the E vector points directly from the positive ion towards the negative ion. At this theoretical point in time there is no H field. The E field will cause the charge particles to move towards each other. This relative motion of positive and negative charge is the simplest example of current. Associated with this tiny current a magnetic or H field will exist. The motion of the positive charge will be in the direction of the E field and the negative charge will move in the opposite direction of the E field. Current by definition flows in the direction of the E field. It follows that positive charge moves in the direction of current and negative charge moves opposite to the current.
Practical Application of above: When I studied electronics in the military, I learned the electron flow version of electronics. When I studied Physics in college, we used conventional current flow. This made remembering things like the left hand rule and right rules for curl etc. very confusing. Thus, I recommend not buying an electron flow version of a text and sticking with conventional current flow.
BASIC ELECTRONICS
The navigation bar to the right is a very comprehensive list of topics in basic electronics and is listed in a suggested order.THIS BASIC ELECTRONICS TUTORIALS SITE
Following a lot of requests from newcomers I have provided a separate page called "starting out in basic electronics". This is a good "check-list" page to start out.If you want a reasonably good grounding don't forget to review electron theory and atoms this is the very basis of electronics.
This chapter basic electronics is the most important of all for newcomers. Without a thorough grasp of basic electronics you will never fully understand the later and much more complicated electronics tutorials. As a suggestion start by reviewing some radio terminolgy A to L and radio terminolgy M to Z, then come back. In particular I would commend everyone to read my page on earth dangers. I think it ought to be compulsory reading.
Here you should gain a full understanding of basics electronics. The basic electronics topics cover everything necessary for your continued understanding of the much more advanced topics presented later.
OHMS LAW, POWER, VOLTAGE, CURRENT AND RESISTANCE
You must have a good grasp of ohms law, an understanding of power, voltage, current and resistance. These are the first fundamental units we work with in electronics.CAPACITANCE, INDUCTANCE, REACTANCE, IMPEDANCE AND "Q"
Capacitance, inductance as well as reactance which leads on to impedance and "Q". These are the next essential units to gain an understanding of basic electronics. Once mastered - ohms law, power, voltage, current, resistance, capacitance, inductance, impedance and "Q" you have then covered the very essentials of basic electronics.MORE BASIC ELECTRONICS - IMPEDANCE MATCHING, TRANSFORMERS
Very popular basic electronics topics are impedance matching and the wide variety of transformers ranging from power transformers, audio transformers and wide band rf transformers. We also have a brief introduction to the topic of baluns.TRANSISTORS, DIODES, INTEGRATED CIRCUITS AND VACUUM TUBES
Obviously in this modern age transistors are the most used active device. This includes the concept that for all practical purposes integrated circuits comprise masses of transistors so arranged as to operate in a specific way. Every basic electronics tutorial should give a reasonable depth of study to these remarkable devices.The basic electronics tutorials will then proceed to deal with diodes in their many forms, integrated circuits both linear and digital. We have included basic electronics tutorials on vacuum tubes or valves because many people believe they offer advantages transistors do not. There has also been renewed interest in vacuum tube technology in recent years if for no other reason than nostalgia.
POWER SUPPLY
We have included the section on power supplies here because it is also fundamental to basic electronics and every project needs a power supply. That tutorial leads you on to a wide range of other regulated power supply topics.NEW! A topic I am frequently asked about - switched mode power supplies. Comprehensive resources provided.
DIGITAL BASICS
Of further interest are the topics on digital basics which of necessity covers a very huge area.Electron theory and atoms
All matter is comprised of molecules, which in turn are comprised of atoms, which are again comprised of protons, neutrons and electrons. A molecule is the smallest part of matter which can exist by itself and contains one or more atoms.Electron theory and atoms
Resistance
In the topic current we learnt that certain materials such as copper have many free electrons. Other materials have fewer free electrons and substances such as glass have practically no free electron movement therefore making good insulators. Between the extremes of good conductors such as silver, copper and good insulators such as glass and rubber lay other conductors of reduced conducting ability, they "resist" the flow of electrons hence the term resistance..Resistance
Ohms Law
Ohms law, named after Mr. Ohm, defines the relationship between power, voltage, current and resistance. These are the very basic electrical units we work with. The principles apply to a.c., d.c. or r.f. (radio frequency).Ohms Law
Current
A flow of electrons forced into motion by voltage is known as current. The atoms in good conductors such as copper wire have one or more free electrons of the outer ring constantly flying off. Electrons from other nearby atoms fill in the holes. There are billions of electrons moving aimlessly in all directions, all the time in conductors.Current
Voltage
Voltage should be more correctly called "potential difference". Voltage is actually the electron moving force in electricity (emf) and the potential difference is responsible for the pushing and pulling of electrons or electric current through a circuit.Voltage
Capacitance
In the topic current we learnt of the unit of measuring electrical quantity or charge was a coulomb. Now a capacitor (formerly condenser) has the ability to hold a charge of electrons. The number of electrons it can hold under a given electrical pressure (voltage) is called its capacitance or capacity. Two metallic plates separated by a non-conducting substance between them make a simple capacitor. Here is the symbol of a capacitor in a pretty basic circuit charged by a battery.Capacitance
Inductance
The property of inductance might be described as "when any piece of wire is wound into a coil form it forms an inductance which is the property of opposing any change in current". Alternatively it could be said "inductance is the property of a circuit by which energy is stored in the form of an electromagnetic field.Inductance
Reactance
Reactance is the property of resisting or impeding the flow of ac current or ac voltage in inductors and capacitors. Note particularly we speak of alternating current only ac, which expression includes audio af and radio frequencies rf. NOT direct current dc.This leads to inductive reactance and capacitive reactance.Reactance
Resonance
Resonance occurs when the reactance of an inductor balances the reactance of a capacitor at some given frequency. In such a resonant circuit where it is in series resonance, the current will be maximum and offering minimum impedance. In parallel resonant circuits the opposite is true.Resonance
Impedance
Impedance is one of the most confusing aspects of electronics - I will de-mystify impedance by taking an extremely casual approach. I have known electronic enthusiasts who still couldn't even mentally visualise the concept of impedance even after 25 years.Impedance
Diodes
Diodes are semiconductor devices which might be described as passing current in one direction only. The latter part of that statement applies equally to vacuum tube diodes. Diodes however are far more versatile devices than that. They are extremely versatile in fact.Diodes
Transistors
Generally transistors fall into the category of bipolar transistor, either the more common NPN transistors or the less common PNP transistor types. There is a further type known as a FET transistor which is an inherently high input impedance transistor with behaviour somewhat comparable to valves. Modern FET's include some very rugged transistor devices.Transistors
Transformers
The name transformers is derived from the fact that when two coils are placed in close inductive proximity to one another the lines of force from one cut across the the turns of the other inducing an ac current, energy is transformed from one winding to another and this is called transformer action.Transformers
Radio Terminology
start in the fascinating and wonderful world of electronics by learning the primary basics - radio terminology. You need a clear understanding of all radio and electronics terms.Radio-Terminology A-L
Radio-Terminology M-Z
Soldering
Among the foremost of reasons an electronic project frequently fails to work properly is due to "poor" soldering practices. This is usually caused by "dry joints" when soldering. Here I discuss the correct procedures for soldering electronic projects.Soldering
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