Component review


UK Power Networks - Circuit Components

In my previous blog, I detailed how I reviewed my notes in order to ease the process of building my project. This is a continuation with a review of the basic components of a circuit.

Key concept

  • Understand what a resistor, LED, capacitor and transistor do


Resistor Stock Photo - Download Image Now - iStock

Resistor: A resistor is a passive electrical component that implements electrical resistance in a circuit. In audio they are used to adjust signal levels. There are many different types of resistors with different values and they determine how much resistance there is within a circuit.

Different resistors can be identified through the colour of their bands.

Resistor Colour Code
Resistor colour band chart

Transistors: A semiconductor device used to amplify or switch electrical signals and electrical power. In simple terms it can turn a current on or off. The two most common transistors are BJT and MOSFET.
Bipolar Junction Transistor: Has 3 legs and includes 3 parts. Base, collector and emitter. If you turn it on the current will be able to flow from the collector to the emitter. If its turned off then it does not work.

Application of bipolar junction transistor (BJT) - Polytechnic Hub
BJT Transistor

MOSFET: It has 3 pins. Gate, source and drain. One important difference between the two is that in the BJT transistor, the current from base to emitter decides how much current can flow from collector to emitter. In MOSFET transistor, the voltage between gate and source decides how much current can flow from drain to source.

Nettigo: N-channel MOSFET transistor, 60V, 16A
MOSFET Transistor

Why a transistor: A great advantage the transistor provides is that you can use a small voltage/current to control a much larger voltage/current.
Furthermore in audio a transistor allows for the existence of an amplifier on and off state.

Capacitor: Much like the name states, a capacitor stores electrical energy in a circuit. It is a passive electrical component with two terminals allowing for connections to both the positive and negative side. Capacitor work like filters. In audio it is quite literal that they are used in LPF/HPF. A clock is an example of an everyday object that uses a transistor.

How Does A Capacitor Work? - Build Electronic Circuits

LED: An LED or light emitting diode is a semiconductor light source that emits light when current flows through it. Its function is to light up if a current flows through it to show that a current is flowing. It is very common and can be seen in many everyday things such as a laptop.

What Is An LED (Light-Emitting Diode)? - Build Electronic Circuits

Practice makes perfect

Now that the basic components have been reviewed, the best way to understand them is to get a hands on experience with them. For my case, before I begin building my circuit I will build basic circuits with the help of circuit diagrams in order to make the whole project easier to understand.

Circuit Diagram | MyDraw
Circuit Diagram


A Fundamental Review

A rapid review

Ultimate Guide to Audio Output - Headphonesty
Different audio Outputs

Before beginning any hands on work for the melody maker, A rapid fire review of the fundamentals of audio electronics was required for me in order to ensure the project runs smoothly. In this blog I will run through concepts that are key to this project so that it may ease the difficulty of the project. You may also learn something however if you choose to stay and read 😀


First things to focus on were the fundamentals. How do circuits actually work. 2 concepts are key to understanding them:

  • Closed loop
  • Voltage, Current and Resistance

Closed loop: Electrons can only flow if there is a closed loop – a path from the negative to the positive terminal of a battery. An example of where a closed loop occurs is a light bulb. Connecting the light bulb to both the positive and negative side of the battery will allow the electrons to flow in order to make it shine a light.

Voltage: Voltage is what makes the electrons move in a circuit. It pushes them onto a wire and the more we have the more ‘power’ we have. In audio more voltage allows for a louder volume. This is why you tend to see small speakers requiring less volts while big loudspeakers or PA systems would require 50 – 100V. V is the symbol for volts.
Resistance: Resistance is a measure of the opposition to current flow in an electrical circuit. The opposite of voltage you could say. It is measured in ohms. Ω is the symbol for resistance.
Current: Current can be described as the rate at which electrons flow past a certain point in a complete electrical circuit. It is measured in amperes. I is the symbol for resistance.

Ohm’s Law

Ohms Law Tutorial and Power in Electrical Circuits
Ohm’s Law

Ohm’s Law states that electric current is proportional to voltage and inversely proportional to resistance.
To remember Ohm’s law just remember this simple triangle. VIR. Voltage, Current and Resistance. Lets say you want to find voltage for a circuit that you are building. Using the triangle you cover your hand over V and what you are left with is I and R. This means Voltage = Current multiplied by Resistance. Using this formula you can find the voltage if the current and resistance is known. You can also do this with finding the current of a complete circuit. Simply hover your hand over I and we can see that V and R are left. V divided by R = I. Overall this is a simple method to help remember Ohm’s law!

More to learn

Now that we remember how a circuit works, we must know review what components make up a circuit and what their function is. This will be featured in my next blog.


Into the World of Arduino

What is it?

Arduino Course for Beginners - Open-Source Electronics Platform - YouTube
Arduino course for beginners –

Arduino is the centre of my project and without it, my project would not be able complete its function (play musical notes). Arduino is a software, IDE specifically, and it allows for computer programmers or coders to write program/code in order to perform functions with a breadboard. Arduino can be downloaded so that it may be used offline or the use of a web editor is also available if you do not want to download it. Arduino code is written in C++.

My Experience

Never used Arduino before however once seeing that it was an IDE similar to Visual Code Studio, my confidence increased as I had experience in coding with Python before. Although my project and python practice may be different in terms of how everything is coded, the fundamentals of the IDE is the same. So far Arduino for me has been quite smooth yet the potential of Arduino is near limitless as I can see how far advanced users may use Arduino. An Arduino board is connected to a laptop/desktop and the code that is written in the IDE, has its functions carried out on the board. Overall it was fun and exciting prospect to getting hands on with Arduino. However safety and care is important. Make sure to avoid eating and drinking around the Arduino board as liquid and crumbs do not go well with the board!!! I had to write this here to remind myself :D.

Everything You Need to Know About Arduino Code
Arduino code –

Format of Code

When writing code for Arduino, Arduino uses a “if-then” structure. All this means in laymen terms is, if a certain condition is met then the board will perform a task such as turning on a sensor. It can be divided into 4 different parts. The setup involves writing code that performs things that only need to be done once. The inputs are then written. The inputs will be used as conditions. The data is then manipulated to perform a function/calculations. The output is the “then” part of “if-then”. If everything is coded correctly then the board should perform said task.

Arduino Starter Kit Multi-language
Arduino Starter Kit –

Arduino’s Versatility

Overall Arduino’s ability to be versatile is very impressive. Initially I underestimated the power of the board and I am left pleasantly surprised with my findings after hours of research. One of my concerns had been if it was too basic however it was simple yet advanced enough for users to build something complex. I was left in awe with how many options people can have with a board.

Smiley face with thumbs up stock illustration. Illustration of drawing -  14491322


Melody Maker – Blueprint

Baby steps

129,458 Blueprint Photos - Free & Royalty-Free Stock Photos from Dreamstime

Step by step

Before I even got the idea for the project, I was quite lost with what to do as a project. I began with a brainstorm to generate ideas. To assist with my brainstorm, I know that I wanted to create something that would produce sound which means it would have a speaker. With my love of producing music, the idea to create melodies was applied to the device and thus the project would become some sort of “instrument”. Research came right after and with the help of Anna, my tutor, I found a melody maker that could be created with an Arduino board.

On 14/2 I decided that the Arduino Melody Shaper was what I wanted to do for the project. To be honest I do struggle with electronics however the prospect of playing melodies through something I created will be exciting. Approval came from my tutor after I had sent an email asking if the project was viable.

Plan of action

My knowledge of Arduino is quite lacking so my plan is after submitting the form I will begin doing 1 hour of work based on learning how to use Arduino. The task will be a challenging yet exciting endeavor as I’ve always wanted to do this kind of thing however I never put the time in to learn. Anna, the internet, my peers and the university, it should be an easier task to complete if any help is required.

I am looking forward to recreating famous melodies such as ABC by Jackson 5 on the instrument. Recordings of famous melodies will be uploaded to this blog once the project has been crafted.