Electronic Components

Conductors, Semiconductors and insulators

Components and Symbols

Resistors

Light Dependent Resistor (LDR)

In electronics, key components drive the magic of technology.

Resistors control current, capacitors store energy, and batteries provide power. Diodes and transistors, both semiconductors, play vital roles—diodes guide current direction, and transistors amplify or switch signals.

Conductors like metals allow smooth current flow, while insulators like rubber block it. These components, with their unique functions, shape our electronic devices and power our modern world.

The best way to learn how they work is to build various circuits and see how they function. This page is a reference to all the basic components that you will use in this course. And the internet is full of more information. It it also important to understand what datasheets are as we need information in component datasheets for design purposed.

There are a lot more information here that you need to get started but you can start building up your electronics knowledge.

Conductors, Semiconductors and insulators

The use of conductors, semiconductors and insulators determine how we can create various electronics circuits.

You have to be able to:

Explain the difference between conductors, semiconductors and insulators
Identify examples of these and why they are used in the specific application

Components and Symbols

Schematic circuits use symbols to show components and different electronics designs.

You have to be able to:

Identify various components in terms of how they look and their symbols

Resistors

These components are probably on the the most used components in electronics. Their values are measured in ohms (Ω), they do what they say (they resist current flow), and they have two main uses:

Voltage Divider (getting the correct voltage to part of a circuit)
Current Limiter (eg: protecting an LED from blowing up)

but more on these two things later...

Initially, we're just going to focus on basic 'linear' resistors - but as you can see from above there are a lot of different types for different tasks. Their main purpose is to control the current.

There are five things that are important when using resistors:

Standard Values

Firstly, resistors have standard values that are shown by colour codes. Always make sure you check or measure the value to ensure you know what the resistor value is. This webpage have activities that may help you learn these. A useful tip regarding the multiplier is to think of it as the number of zeros. For example:

brown black black is 1 then 0 then 0 zeros (or no zeros). Or just 10 - so 10Ω (ohms).
green blue yellow is 5 then 6 then 4 zeros. So its 560000Ω. Substitute 'k' for 3 zeros: 560kΩ

You can also use a color code calculator to help you.

Parallel Resistors

Resistors can be connected in parallel as shown on the right to make up "new" resistor values or depending on other components use in a circuit. The new resistance will always be lower than the lowest resistor used to make it.

The simplest parallel resistor arrangement is two resistors of the same value, which will give 1/2 the resistance (ie: two 10kΩ resistors in parallel will give you 5kΩ). This expands neatly - three 10kΩ resistors gives 1/3, or 3.33kΩ. Four would be 1/4 and so on. Important to note is that the voltage over these resistors are the same. More information here.

Series Resistors

Resistors can be connected in series as shown to make up "new" resistor values or depending on other components use in a circuit. The new resistance is simply the sum of the resistors used. For example, two 10kΩ resistors in series would give you 20kΩ. Important to note is that the current through these resistors are the same. More information here.

Light Dependent Resistor (LDR)

An LDR is a variable resistor who's resistance is changed by the level of light on its surface.

Although the amount of resistance has a relationship to the amount of light, it is not linear, ie: twice the light does not necessarily mean twice (or half) the resistance. More info in the reference.

Reference: http://www.technologystudent.com/elec1/ldr1.htm

Capacitors

A capacitor is a passive, two-terminal that is used to store electrical charge. Basically it consist of two metal plates separated by an insulator called a dielectric. The size of the plates, A, the distance between them, d, and the dielectric constant of the separating material determine the capacitance. This capacitance time the voltage over the plates, determines the amount of stored electric charge.

When a capacitor is connected across a voltage, current flows into the plates for a short time. We call this "the becomes charged up". It will store this charge, even if the source of the voltage is removed. The capacitor will now have voltage across it because of the charge now stored on its plates. This effect is used in a variety of circuits including power supply filtering, frequency oscillators, radio receivers.

Some good links to help with your understanding of capacitors:

How Stuff Works - How Capacitors Work
Sparkfun - Capacitors
Electronics Tutorials - Introduction to capacitors
Very good explanation on You Tube - What is a Capacitor? (below)
Capacitor simulation from PHET Interactive simulations.

A good analogy for a capacitor is provide by How Stuff Works. There is a simulation circuit in Yenka showing how the capacitor charge and discharge.

There are a number of different types of capacitors:

Dielectrics capacitors - normally variable capacitors used in transmitters and receivers
Film Capacitors - high power applications
Ceramic capacitors - Resonant circuits, DC-DC converters, used on brushed DC motors to minimise RF noise.
Electrolytic Capacitors - Power supply filtering, filters in audio amplifiers

Batteries

Batteries are handy to use as a power source for various circuits although a constant voltage from a bench power supply or even the USB port from a computer may be more reliable options as batteries goes "flat" and the voltage you think it is, is not always what it is. Always measure the battery before use.

This website has good information for you to choose a power supply.

Diodes

The key function of the diode is to control the direction of current flow. Current can only flow in one direction through a diode.

Diodes have many useful applications for example:

Rectifying a voltage, such as turning AC into DC voltages. For example a bridge rectifier. This is also a good explanation of the full bridge rectifier.
Isolating signals from a supply
Voltage Reference
Controlling the size of a signal
Mixing signals
Detection signals
Lighting
Lasers diodes

Transistors

Transistors are used in almost all electronic devices to amplify or switch signals. Many people are using electronics either as part of their jobs or as a hobby. There are many websites and books that describe how transistors works. This is a list of some of the more interesting ones:

Electronics Components: Use a Transistor as a Switch
Sparkfun is also a good place to learn about transistors
See How Transistors Work – A Simple Explanation
Technology Student
Understanding BJT Transistors and How to Practically Use Them in Your Designs

The following transistor circuits can be created easily using the standard BC547. Make sure you do simulate it on Yenka or other simulation applicationto develop your understanding: