When I want to build something, whether it is prototyping something with the Arduino, coding an application or building wooden steps to our back door, I usually try to break the project down into individual blocks. It really helps me focus on each individual part of the design rather than getting overwhelmed by the whole design. We can usually break an electronic project into four separate blocks. The following diagram illustrates how these blocks work together:

Let's look at each one of these blocks starting with the power supply.

The power supply is the source of electricity for the project. For most of the experiments in this book, the power supply will be some low-voltage...

A multimeter, also known as a Volt-Ohm-Milliameter, is an electronic measuring instrument that is typically used to measure voltage, current, and resistance. There are analog multimeters that operate by moving a pointer to display the measurement, but today most multimeters are digital with an LCD that is used to display exactly what the measurement is.

A multimeter can cost as low as USD $10 and up to USD $400 for a really nice Fluke 87V. Unless you are planning on using the multimeter for professional purposes, I would recommend getting a low-cost multimeter like the ones shown in the following photograph:

The digital multimeter has three main parts, which are the display, selection knob, and the probe ports.

The display will show what the measurement is. Some of the higher-end multimeters have a backlit display to make it easier to read in low light.

The selection...

There are numerous types of electronic components that we will be using in our projects. These components can be obtained for a relatively low cost from many online retailers. It is important to be familiar with what some of the more popular components because they will be used in many of the circuits we create. Let's start off by looking at the component that we will be using is almost all circuits that we create, the resistor.

The resistor will be used in almost every circuit that we create. A resistor is an electronic component that has a specific amount of electrical resistance that never changes. The resistor limits the flow of electrons in the circuit. We will see how resistance works...

Everything in the universe is made up of atoms. Atoms are made up of three primary components, which are the proton, neutron, and electron. The protons and neutrons make up the nucleus of the atom while the electrons orbit the nucleus like the moon orbits the Earth. The proton has a positive charge and the electron has a negative charge.

Electricity is created when particles become charged. Some particles become positively charged while others becomes negatively charged. Particles with opposite charges attract each other while particles with the same charge repel each other.

Since the electrons are in constant motion, occasionally an electron will escape from its atom and joins another atom. The atom that the electron escaped from now will have a net positive charge while the atom that gained the electron while having a net negative charge. Electricity is...

Current, in an electronic circuit, is the flow of the charged particles (electrons). The current is measured by the number of charged particles passing the point of the circuit, that is being measured, per second.

Current is measured in amperes and can be measured with most standard multimeters. One ampere is equal to 6.241×10¹⁸ electrons passing the point being measured per second.

If we think of electricity as water flowing through a pipe, the following diagram will help visualize what current is:

Voltage is the amount of potential energy between two points, where one point has more charged particles than the other. The difference in this charge is called the voltage. We can think of the voltage as the pressure within the circuit to push the charged particles through the circuit. Voltage is measured in volts.

To continue with the water in a pipe analogy, we can think of voltage as the water pressure within the pipe pushing the water through. The following diagram illustrates this:

Resistance is how much the flow of current is reduced or impeded. All circuits have some resistance from the wire and components that make up the circuit; however, most circuits include resistors that add extra resistance to the circuit. These resistors enable us to limit the flow of charged particles within the circuit. Resistance is measured in Ohms.

Using the water in a pipe analogy again, resistance is the smallest part of the pipe that is impeding the water flow.

Now let's see how these three properties work together by examining Ohm's law.

Ohm's law stated that the current flowing through a circuit is directly proportional to the voltage applied to the circuit. This means that if the voltage of the circuit increases, then the current will also increase if the resistance stays the same.

Ohm's law also states that current flowing through a circuit is inversely proportional to the resistance of the circuit. This means that if the resistance of a circuit increases, then the current flow will decrease if the voltage stays the same.

The standard formula for Ohm's law states that the current is equal to the voltage divided by the resistance:

While the preceding formula is how Ohm's law is usually introduced, it really consists of three formulas:

I = V/R

R = V/I

V = I*R

In this book, we will use the R = V/I the most to calculate the resistance needed...

Power is the amount of electrical energy transformed into another type of energy (heat, light or work) per second. Power is an important concept because it is what allows our electric circuit to do something. For example, if we created a circuit with a battery and a resistor, the resistor will convert the electrical energy to heat (or thermal) energy. All resistors also have a maximum power rating that they can handle therefore to ensure that we do not damage the resistors in a circuit we will need to know how to calculate power. Power is calculated by multiplying the voltage by the current and is measured in Watts.

Most of the low-cost resistors that we can get from online retailers are rated at 1/4 (or 0.25) Watts so we will assume that the resistors we are using for the projects in this book are rated at that 1/4 Watt. Now let's say in our project we are...

The value of a resistor is marked on its body using color bands. The majority of the resistors contain four bands but there are also some resistors that have five and six bands. The following picture shows what a resistor with four bands looks like:

With a four-band resistor the first two bands, from left to right, indicate the resistor's value. The third band is the multiplier and the fourth band is the tolerance. Resistors that have five bands use the first three bands to indicate the resistor's value, then the fourth band is the multiplier and the fifth band is the tolerance. The following table shows the color values:

In this chapter, we gave a very brief introduction to electricity and some of the more popular electronic components that we will be using later in this book. This chapter will give you enough knowledge to get you started building very basic prototypes. It is recommended that once you start more advanced projects you do further reading on electricity and electronic components.

In the next chapter, we will look at circuits and how to read circuit diagrams.