A lot of people desire so much to know the concepts of electronic circuit design from scratch. Well, designing simple lighting systems with bunch of light emitting diodes and resistors may not really pose problems, but becoming good at designing complex electronic systems is not a child’s play. Nevertheless, there is no limit to what anyone can achieve if they are bent on doing so.
As the famous Chinese war Lord Lao Tzu says:
A journey of a thousand miles begins with a step, to master (at least to a reasonable length) how to design electronic circuits, one need to start from scratch and master the basic indispensable principles of electronic circuit design.
What you’ll learn in this Electronic Circuit Design Tutorial
I will assume you are a beginner in electronic circuit design; hence, I’m going to simplify the tutorial in the best possible way.
In this tutorial, we are going to learn:
- The concept of loops
- The concept of resistance
Please note that the success of every electronic circuit designer lies on their willingness to practise, therefore, we are going to start the tutorial with practical hands-on learning.
If you don’t like the video or need more instructions, then continue reading.
You will need the following electronic components:
- One Breadboard
- Jumper wires (Male-Male)
- One 100K resistor
- two 1k resistors
- Two 9 volts batteries
- Two red light emitting diodes (LED)
- Two pushbutton switches
You can click on the amazon links to buy the components.
Observe the circuit connections below and connect them as shown. I already made a tutorial on Breadboard.
If you connected the circuits properly, when you press switch S1, with your finger firm on the switch, LED1 will come ON glowing brightly, then, if you remove your finger, LED1 will go OFF. Same thing happens when you press switch S2, the only difference being that LED2 is less bright than LED1.
The Concept of Loops
When switch S1 is pressed with the finger held firm on the switch, the contact points indicated with red arrow joins together closing up to create a complete closed path of current flow with no gap existing anywhere in the circuit, as a result of this closed circuitry, the light emitting diode (LED) comes ON. In this situation, conventional current (current moving from the positive end of the battery) flows from the battery, moves past the closed switch S1, it again passes resistor R1, moves down to LED1, lights it up and returns back to the negative end of the battery. However, when the finger is released from switch S1, the contact points of the switch separate thereby creating an opening in the circuitry. This opening prevents current from moving from the positive end of the battery to the negative end, hence creating an open circuit which causes the LED1 to go OFF.
Now, here is the point, for current to flow in a circuit, there must be a closed path. This path constitutes what is called a “LOOP”. A loop can be either open or closed. A closed loop means there is no gap in the circuitry hence there could be current flow if the necessary components are well connected. An open loop at the other hand means there is a gap in the circuitry; hence there will be no current flow even if all the necessary components are well connected. Sometimes open loop and closed loop are referred to as “OPEN CIRCUIT” and “CLOSED CIRCUIT”. For your circuit to work in the first place there must be a closed loop in the circuitry.
The Concept of Resistance
If you press switch S2, same action will be observed as in the case of pressing switch S1. But, here is the difference, LED1 glows brighter than LED2. Why? Well, if you think it’s the resistor, you are correct. Resistor as the name implies, resists the rate of flow of current in an electronic circuit. Now think of a resistor as a speed breaker or a bump on the road, if you are riding a bike and bumps on a speed breaker, the amount of impact on you is proportional to the size of the speed breaker, the greater the size of the speed breaker, the stronger the impact and resistance.
The duty of the 1kΩ on the LHS circuit is to reduce the rate at which current flows to the light emitting diode LED1 and also to take up some voltages of the 9v battery. Supposing the battery is 2 volts(which is the recommended for light emitting diodes) the resistor will be taking up negligible or no voltage from the battery, however, we still need to connect the resistor, so that it limits or reduces the rate of current flow in the circuit, to avoid damaging the LED. The more you increase the resistance of the resistor, the more you limit the rate of current flow, the more the brightness of the LED reduces. The LHS circuit has a resistance equivalent to 1kΩ, while the RHS circuit has a resistance equivalent to 1kΩ + 100kΩ = 101kΩ, you can see the difference, and that is why the brightness of the two light emitting diodes are far from having the same intensity. This teaches that a resistor is an indispensable component in electronic circuit design. A lot can be done with a resistor in a circuit.
- Open loop means there is gap in the circuit, hence no current flow
- Closed loop means there is no gap in the circuit, hence current can flow
- The greater the size of the resistor in a circuit, the greater the resistance and the smaller the rate of current flow
- The smaller the size of the resistor in a circuit, the smaller the resistance and the greater the rate of current flow
We shall discuss more on resistors and their applications in the future; there is a lot to know about resistors. You can also read the Difference between Current and Voltage.