Daktologist's Beginners Guide to the World of Electronics and Electricity

DaktologistDaktologist Global Moderator
edited August 2011 in Spurious Generalities
Daktologist's Guide to Electronics




Electricity. It's all around us, from our appliances to our vehicles to lightning and static. In this guide I will go into the subject of electronics.

Firstly what is electronics and how does it differ from electricity in general?. Well electronics deals with using electricity to perform complex tasks like amplifying sound, measurement and many other things.

If you want to take electronics up as hobby or take things further and do it as a job, you are going to need a few basic things.
  • Screwdrivers such as the cross head and flat headed screwdrivers
  • Wire cutters and pliers
  • Soldering iron
  • Multimeter
  • Wire Stripper
  • Knife

If you can afford it and want a few extra tools you can get things like
  • Oscilloscope
  • Variac
  • Adjustable temperature soldering station
  • Drill Press

Firstly I will explain the basics of electronic circuits.
  • The Parallel Circuit

In the picture below you will see two components connected to a battery, Take note of how they are connected. This is a parallel circuit, Each component receives the same amount of voltage but slightly less current flows through each component as they share the total between them.



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  • The Series Circuit
In the picture below you will see two components connected to a battery, They are connected together in series. Each component receives less than the total voltage but receives the same amount of current as the others.



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Next I will explain the uses of different components, you will come across the following
  • Capacitors
  • Resistors
  • Inductors
  • Diodes
  • Integrated Circuits (IC's)
  • Transistors
And if you are lucky Vacuum tubes such as.
  • Triode
  • Pentode
  • Diode


Capacitors

Capacitors store charge between two plates of metal separated by an insulator such as plastic, paper, air and many others depending on the type of capacitor. Basically they act like a tank that can hold electrical energy in differing amounts depending on size which is measured in Farads. Capacitors have many uses from radio tuning to power supply filtering and much more. Below is a picture of a variety of capacitors.



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Resistors

The Resistor is a component that limits electricity flowing in a circuit. The term used to describe this "limitation" is resistance and it is measured in Ohms. Light bulbs and electric heaters are a form of resistor as limiting the flow of electrons creates heat which in turn creates light and heat in your lights and heaters. Below are some examples of resistors



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Inductors

Inductors are basically a coil of wire either wrapped around an iron core or coiled up as so to have an air core depending on the design and intended use. Inductors are used in power supply filtering, radios, as well as "electromagnets". Passing an electrical current through a coil of wire creates a magnetic field and if the inductor has an iron core can hold energy like a capacitor although for a much shorter period of time.



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Diodes

The diode can either be a vacuum tube or made from a semiconductor such as silicon. All modern diodes are made from silicon or another semiconducting material. A diode limits current flow to one direction only and basically acts as a one way valve, they also produce light as seen with light emitting diodes (LED's). They are commonly used to convert Alternating current into Direct current. This I will explain later. Below are some examples of some diodes.



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Integrated Circuits (IC's)

IC's can take many forms and have many different uses such as computer CPU's, SSD's Amplifiers and much more. Below are some examples of some IC's



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Transistors


A transistor is a semiconductor device used to amplify or switch electrical current. They normally have three terminals called: Base, Collector and Emitter. When current is passed from the collector to the emitter nothing will happen until current is applied to the base terminal which causes it to conduct. This is how an amplifier works, a weak audio signal is applied to the base and when a large amount of current is passed from collector to emitter, it takes the form of the original audio signal although many times larger. Below are some examples of transistors.



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Vacuum tubes


The Triode:

The triode behaves similar to the transistor accept at a much higher voltage. It consists of a glass tube that contains a filament encased in a metal tube called the cathode, a metal grid and a metal plate called the anode. The glass tube is under a vacuum as air interferes with the travel of electrons in the tube. The grid sits between the anode and cathode which are spaced apart. During operation the filament is heated which in turn heats the cathode to red heat and current is then passed from the hot cathode to the cold anode. When used as an amplifier the audio signal is applied to the grid which regulates the current flow from cathode to anode, the current from the anode which is now in the form of the audio signal is now many times stronger and depending on the amplifier is passed to the grid in another triode to be amplified more or passed directly to the speakers via a matching transformer.



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The Pentode:


The pentode is similar to the triode except it has three grids between the anode and cathode. They are basically a much more powerful version of the triode and are used in power amplifiers.



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The difference between AC and DC

You are probably wondering what the fuck i'm on about when I mention AC and DC current. AC or Alternating current is current that constantly changes direction many times per second. Its what comes out of your wall outlet and if you are in the US it changes direction 60 times a second and if you are in Europe or most other places in the world, it changes direction 50 times a second. this change is measured in Hertz (Hz) which basically means "cycles per second". The mains is in the form of a sine wave.

Direct current or DC is what comes from batteries, solar panels and things like computer PSU's and what not. It flows in one direction only. Below are some pictures I took that explain the difference clearly.

AC current.



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DC current



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Due to electronic equipment on the same line as you the sine wave can become distorted as shown below. Note the flat peaks of the wave.



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Electronic test equipment

Below are some common pieces of test equipment.

The Oscilloscope.

The oscilloscope is a very useful tool for electronics testing. It will show the waveform of any current flowing in a certain part of a circuit. Say for instance you have an amplifier that isn't giving any output. You would go and grab your oscilloscope, connect a signal source to the input and follow the signal path through the circuit to see what part isn't amplifying the signal properly. Or you have a digital circuit that is acting weirdly, you can test to see what the output waveforms look like and compare those to the data sheet for that particular device. It can also be used to check the filtering circuit on a AC to DC power supply to ensure it is filtering the DC correctly.



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The Multimeter

This multi purpose tool can test AC current and voltage, DC current and voltage, resistance, frequency, capacitance, and continuity and depending on the meter; inductance and temperature. You should have at least one in your tool box if anything.



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Transformers

A transformer is a device that allows AC voltage to be increased or decreased. They find uses in the electricity distribution network, appliances and audio equipment. Normally they are designed with a fixed voltage in mind. However there are devices called "autotransformer's" or "variacs" as they are commonly known which are variable transformers and can provide a range of output voltages from 0 volts to 20 volts above its input voltage. Autotransformer's have one winding where regular transformers have two and isolate the input from the output. This effect is exploited as a safety device which makes it safer to use power tools outdoors as well as blocking DC from entering the speaker coils in an amplifier among other things.

Isolation transformer



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Autotransformer



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Inverters

An inverter converts DC into AC and are commonly used in UPS's and in motor homes as well as in homes that are off the grid. These devices use transistors to create a continuously changing current similar to the mains waveform although more expensive models produce pure sine wave AC rather than this pretend sine wave as the photos of the waveform my UPS produces show below show.



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This is what is referred to as modified sine wave AC.


Daktologist

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