The Rectifier Diode

Diode allows current to flow in one direction only. It looks a lot like a resistor, as you can see


These diodes can protect parts of the circuit against reverse current flow, but there is a priceto pay: diodes also cause a drop in the voltage of around 0.7 V. The 1N4004diode is rated to handle 1 A and 400 V, much higher than we will be using.It’s a tough, common, and low-cost diode.

The capacitor

A capacitor is a device that holds an electric charge. It consists of two metal plates with an insulating layer that allows an electric charge to build up between the plates. Once the current is stopped, the charge remains and can flow out of the capacitor (called discharging the capacitor) .

The amount of charge that a capacitor can store is measured in farads, and one farad is actually a very large amount. Therefore, you will generally find capacitors with values measured in picofarads or microfarads

Reading Capacitor Value


The first two digits represent the value in picofarads, and the third digit is the multiplier in tens. For example, the capacitor shown in Figure 4-12 is labeled 104. This equates to 10, followed by four zeros, which equals100,000 picofarads/pF .

Types of Capacitors

Our projects will use two types of capacitors: ceramic and electrolytic.

Ceramic Capacitors

Ceramic capacitors, such as the one shown below , are very small and therefore hold a small amount of charge. They are not polarized and can be used for current flowing in either direction. The schematic symbol for a nonpolarized capacitor is shown in Figure 4-13. Ceramic capacitors work beautifully in high-frequency circuits because they can charge and discharge very quickly due to their small capacitance.


nonpolarized: U can connect the component in any direction/orientation ,no positive and negative terminal.

Electrolytic Capacitors

They are bigger than ceramic capicator hence can store large and have large capacitance , A mark ing on the cover shows either the positive (+) side or negative side (–).you can see the stripe and the small negative (–) symbol thatidentifies the negative side. Like resistors, capacitors also have a level of tolerance with their values.


Electrolytic capacitors are often used to make smooth power supply voltages.

Push button:

As the name satates when we push the button it allows to pass the current .


Notice how the button at the bottom of the figure is inserted into the breadboard, bridging rows 23 and 25. When the button is pressed, it connects the two rows. The schematic symbol for this particular push button is shown above  The symbol represents the two sides of the button, which are numbered with the prefix S. When the button is pressed, the line bridges the two halves and allows voltage or current through.

piezoelectric Buzzers ( make some noise………….)

A piezoelectric element (piezo for short), or buzzer, is a small, round device that can be used to generate loud and annoying

noises that are perfect for alarms—or for having fun.


When alternating current is applied (such as on . . . off . . . on . . . off). the plate vibrates and generates sound waves.It’s simple to use piezos with Arduino. The piezo elements are not polarize.

i have attach the pdf of basic electronic component. we will study some more components later…..

About electricity


Basic Electronic Components


To design a working model we need hardware .the basic building blog of a circuit are electronic components:


The Resistor

Various components, such as the Arduino’s LED, require only a small amount of current to function—usually around 10 mA. When the LEDreceives excess current, it converts the excess to heat—too much of whichcan kill an LED. To reduce the flow of current to components such asLEDs, we can add a resistor between the voltage source and the component.Current flows freely along normal copper wire, but when it encounters aresistor, its movement is slowed. Some current is converted into a small amount of heat energy, which is proportional to the value of the resistor.

given is  an example of commonly used resistors

Arduino Workshop A Hands-On Introduction with 65 Projects


The level of resistance can be either fixed or variable. Resistance is measured in ohms (W) and can range from zero to thousands of ohms (kiloohms,or k W) to millions of ohms (megohms, or M W).

Reading Resistance Values

Resistors are very small, so their resistance value usually cannot be printedon the components themselves. Although you can test resistance with a multimeter,you can also read resistance directly from a physical resistor ,even without numbers.One common way to show the component’s resistanceis witha seriesofcolor-codedbands ,read  from left to right,as follows:

First band Represents the first digit of the resistance

Second band Represents the second digit of the resistance

Third band Represents the multiplier (for four-band resistors) or the third digit (for five-band resistors)

Fourth band Represents the multiplier for five-band resistors

Fifth band Shows the tolerance (accuracy)

Table 3-1 lists the colors of resistors and their corresponding values


Colour                           ohms


Black                                   0

Brown                                  1

Red                                     2

Orange                               3

Yel low                                 4

Green                                 5

Blue                                     6

Violet                                   7

Gray                                     8

White                                   9


The Light-Emitting Diode 

“World is beautiful when we add colours”

The LED is a very common, infinitely useful component that converts elec-trical current into light. LEDs come in various shapes, sizes, and colors.Here fig shows a common LED.


Connecting LEDs in a circuit takes some care, because they are polarized;this means that current can enter and leave the LED in one direction only.The current enters via the anode (positive) side and leaves via the cathode(negative) side, as shown in Figure 3-7. Any attempt to make too muchcurrent flow through an LED in the opposite direction will break the component.Thankfully, LEDs are designed so that you can tell which end is which.The leg on the anode side is longer, and the rim at the base of the LED is flat on the cathode side, as shown below:


When using LED for your ARDUINO Project . you need to consider the operatingvoltage and current. For example, common red LEDs require around 1.7 Vand 5 to 20 mA of current. This presents a slight problem for us, becausethe Arduino outputs a set 5 V and a much higher current. Luckily, we canuse a current-limiting resistor to reduce the current flow into an LED. But which value resistor do we use? That’s where Ohm’s Law comes in.

To calculate the required current-limiting resistor for an LED, use thisformula:


Where Vs = Arduino output 5 voltage  Vf = Led forward voltage

When in doubt, always choose a slightly higher value resistor, because it’s better to have a dim LED than a dead one!

The Transistor

A transistor can turn on or off the flow of a much larger current than the Arduino can handle. We can, however, safelycontrol a transistor using an Arduino digital output pin.A popular example is the BC548, shown below:

tran               bjt


Operation of transistor can be understood using the tap as the value behaves as the base when we off the value no water flows and when value is switched on water flows through it.


About Electricity


Let’s spend a bit of time discussing electricity, since you’ll soon be buildingelectronic circuits with your Arduino projects. In simple terms, electricity is aform of energy that we can harness and convert into heat, light, movement,and power. Electricity has three main properties that will be important tous as we build projects: current, voltage, and power.


The flow of electrical energy through a circuit is called the current. Electricalcurrent flows through a circuit from the positive side of a power source such as a battery, to the negative side of the power source. This is knownas direct current (DC). For the purposes of this book, we will not deal withAC (alternating current). In some circuits, the negative side is called ground(GND). Current is measured in amperes or “amps” (A). Small amountsof current are measured in milliamps (mA), where 1,000 milliamps equal1 amp.


Voltage is a measure of the difference in potential energy between a circuitpositive and negative ends. This is measured in volts (V). The greater thevoltage, the faster the current moves through a circuit.


Power is a measurement of the rate at which an electrical device convertsenergy from one form to another. Power is measured in watts (W). Forexample, a 100 W light bulb is much brighter than a 60 W bulb becausethe higher-wattage bulb converts more electrical energy into light.A simple mathematical relationship exists among voltage, current,and power:

Power (W) = Voltage (V) × Current (A)


These prefixes are universally used to scale units:

Multiple   prefix     symbol

1012            tera           T

109             giga           G

106            mega         M

103            kilo             k

10-3          milli          m

10-6          micro        µ

10-9          nano        n

10-12         pico         p

10-15      femto         f