What Are The Parts Of A Circuit Board

If you are a beginner in the electronics and electrical industries, a printed circuits board parts diagram will seem overwhelming to you.  Also, it might seem intimidating even to some professionals. And it is natural since a circuit board will at least require 13 components to build up the entire circuitry board for different purposes.

When you know what are the parts of a circuit board and their primary usage, you can identify the faults in it and also, use the PCB with enhanced effect. Hence, we will discuss these essential components to build a circuit board for commercial purpose properly.

Table of Contents

How To Identify SMD Components In Circuit Board?

SMD components most commonly refer to the Small Mounted Devices and are electronic parts. These are used on a circuit board with soldering. It uses surface-mount technology for the soldering process.

Depending on the SMD components setup, they serve different purposes. The industry experts have setup different SMD components sizes standard for various purposes.  The most common SMD components include Chip Resistor(R), Network Resistor (RA/RN),  Capacitor, Transistor (Q), LED, Diode and so on.

These are also the fundamental parts of a circuit board that we will discuss in the following detail.

What Are The Parts Of A Circuit Board?

Many people continuously ask us about circuit board components and what they do to understand the circuit board diagram better. And it is a worthwhile question since without knowing the parts and their applications, you may not use the circuit board properly.

So, in the following sections, circuit board components explained briefly.

1. Resistors:

All types of Printed Circuit Boards (PCB) use resistors as the current control foundation. Resistors are two ends of electronic components and allow a controlled current flow through them at ease. As the two terminals permit current flow, it generates the required voltage for the circuit board operation.

A resistor controls the current flow or restricts it by converting the voltage into heat. Once converted into heat, the resistor dissipates it to cool off the entire circuit board diagram. You can find several materials used for resistors manufacturing, but the most common is a carbon film. It is often found in the axial style, and the different color coding means various levels of resistance from the component.

Color Codes Resistance Level (In Thousands)

2. Capacitors:

A capacitor of the circuit board functions as the location to store energy. While PCBs use the resistor to control the adequate electric charge, the function of a capacitor is to keep the charged energy temporarily.

Hence, many people compare them to batteries. Also, a capacitor I fully charged and emptied within a spilt of seconds. The capacitor uses two metal conducive ends and store both positive and negative charges. It releases the temporarily stored charge when the circuit board needs electricity supply when need be.

Depending on the conductive metal plate used to build the capacitor, you will find several types of capacitors in the market. However, most PCB builders will use radial, polyester or ceramic capacitors for the circuit board.

3. Transformers:

The transformers in a circuit board do what they meant to do- transfer power or electricity from one source to another. They do the power transformation with the use of induction technology.  The PCB transformer continuously decreases or increases the voltage as part of its electricity transformation into different parts of the circuit board.

Likewise, the resistor, a transformer also regulates the flow of the electricity. But the difference between a resistor and transformer lies in their functioning. A transformer isolates the electricity flow to control it.

There will be ardently at least two or more separate windings or inductive circuits in a PCB transformer along with a soft iron core. The primary winding works as the source terminal to dissipate the energy. The secondary winding works as the energy receiver.

4. Transistors:

The circuit board transistor works as the foundation block for the most modern-day electronic components. A PCB transistor works to amplify the small charge coming from the batteries and enables the PCB to work finely.

You will most usually see a bipolar transistor in the circuit board. It has three pins and three locations to store and amplify the electric charge. NPN and PNP are the two kinds of transistors. These consist of the following parts:

  • Base: it works as the foundation of the entire transistor.
  • Collector: As the name suggests, the collector accumulates the charger carrier.
  • Emitter: The charge is emitted or released in this area.

There are both N-type and P-type areas on the transistor.

5. Diodes:

The purpose of the diode is to redirect the electrical energy in the circuit board. It works similarly as the one-way street to shift the power from one end to another. The component has two terminals. One end blocks the electricity flow, and the other end forces the one-directional flow of the electricity.

The flow direction is from the anode (positive terminal) to the cathode (negative terminal). The diode has a similarity with the resistors since it controls the electricity flow. The most common diode system is a Light Emitting Diode or LED.

6. Battery:

We all know the purpose of using a battery on the circuit board. The PCB battery stores the energy in the chemical formation and then converts it into electrical energy.  The battery uses an external circuit. It permits the flow of the electrons from one end to another.

In this way, an available current is produced, but it is constrained. The transistor then amplifies the limited electrical power.

The most recommendable battery used in the PCBs is a rechargeable battery.

The flow direction is from the anode (positive terminal) to the cathode (negative terminal). The diode has a similarity with the resistors since it controls the electricity flow. The most common diode system is a Light Emitting Diode or LED.

7. Integrated circuits:

It is the powerhouse most commonly used for the PCBs. An integrated circuit board comprises of resistors, transistors and capacitors in millions and has a tiny wafer shape.

Since it has millions of transistors, capacitors and resistors, the integrated circuit works as an oscillator and amplifier for the PCBs. The ICs are integrated into the PCB base with the miniature technology that has seen widespread use lately.

ICs have silicone construction and plastic housing. Ideally, you will see analog and digital ICs and both have widespread use in the PCB manufacturing industry.

8. Inductors:

Working as a linear passive component, the inductor is another integral part of the circuit boards diagram. It is a two-terminal component, likewise the capacitors. It uses a magnetic field to store the energy before dissipating it to other parts.

Inductors are also widely called as reactors, chokers and most popularly, coils. The insulated wire is wrapped within the core. The higher the core wrapping or coiling of the insulated wire, the higher the magnetic field and energy will be.

The inductance promptly of the inductor is formulated by the ratio of voltage and current rate change within a certain period.

9. Oscillators:

The oscillators work like a clock or programmable timer in the PCBs. It generates an electronic signal periodically. The piezoelectric material used within the oscillators produces resonance, and it dictates the electric signal frequency or oscillation.

The most common piezoelectric material used to manufacture the oscillator is the quartz crystal.

10. Switch:

The primary function of a switch in the Printed Circuit Board is to control the electricity flow through on/off functions.

When pressed down the switch open ups the entire circuit board and permits the other functions to take place within it, and when you turn off the switch, the whole of electrical operation comes in a standstill.
Manufacturers choose from literally tons of options for switches used in the PCBs.

11. Potentiometer:

A potentiometer has three terminals and serves as a variable resistor. It dictates the voltage or electric potential of the PCBs and allows you to control the voltage flow.  There two main types of the potentiometer in the market.

These are, firstly the linear and secondly, the rotatory ones. Rotatory potentiometers are more familiar than the linear ones. Also, these use a knob to control the variable resistance. The potentiometer controls the amplifier voltage.

You will see them mostly in the volume control mechanism of any devices.

12. The SCR:

The Silicon Controlled Rectifier or SCR has four silicone layers and is placed in a PCB to control the high amount of electricity and voltage. The easiest way to define an SCR is to imagine two transistors which are cooperating for the voltage control.

However, manufacturers will use them where a regular transistor may not work. One such example could be the circuit boards used in the ACs.

13. Sensors:

The sensors are placed in a PCB to dictate the minimal changes in the surrounding and act accordingly. It senses heat, noise, motion, moisture, light, etc. The changes are carried to the PCBs through an electrical signal. Also, some programmed sensors display these changes in a display with readability for humans.

Where Can I Buy Circuit Board Components?

You will get the components for circuit boards, mostly in the nearby hardware and electronics shop. So, sourcing the elements is pretty easy. Also, you can choose any reputed online store to buy these components.


Since now you know what are the parts of a circuit board, you should find it pretty straightforward to collect them and build the first circuit board of your life. The best part of these 13 circuit board components is that they are easily gettable and none would cost you much. So, what’s your plan on manufacturing a circuit board with these parts?

Peter Gong
Peter Gong

I am Peter Gong. I have been working in PCB and PCBA industry for 15+ years now. I have been a part of the PCB revolution with my dedication to circuit board technologies and creative ideas. I write in FX PCB to impart my knowledge on PCB and PCBA for all circuit board lovers, manufacturers, and users.