Diodes are small electronic components that come in various sizes and shapes. Most commonly, they have a black cylindrical body with a stripe at one end and metal leads for connecting to a circuit. The end with the stripe is called the cathode, while the other end is the anode. Understanding these terms is important for using diodes correctly.
Diodes are like one-way gates for electricity. Imagine a water pipe with a swing valve: water can push the gate open and flow through, but if the water tries to flow backward, the gate closes, stopping the flow. Similarly, diodes allow electrical current to flow in only one direction. This property is useful for controlling the flow of electricity in circuits.
When we talk about electricity, there are two ways to describe the flow of electrons: electron flow and conventional flow. Electron flow is the actual movement of electrons from the negative side to the positive side. Conventional flow, which is often used in electronics, describes current as flowing from positive to negative. It’s important to know which one is being used in explanations.
If you connect a diode in a simple circuit with an LED, the LED will light up only when the diode is installed correctly. This is because the diode allows current to pass in one direction. When the stripe end (cathode) is connected to the negative side and the other end (anode) to the positive side, the diode conducts electricity, known as forward bias. If you reverse the diode, it blocks the current, acting as an insulator, called reverse bias.
Diodes are crucial for protecting circuits. If a power supply is connected incorrectly, a diode can prevent damage by blocking the current. Diodes are also used to convert alternating current (AC) into direct current (DC). AC current moves back and forth, creating a wave with positive and negative parts, while DC current flows in one direction, forming a steady line.
To convert AC to DC, you can use a diode. When connected to an AC supply, the diode allows only the positive half of the AC wave to pass, creating a rough DC output. This is known as half-wave rectification. To improve this, you can use four diodes in a configuration called a full-wave rectifier. This setup allows both halves of the AC wave to pass, inverting the negative half to positive, resulting in a smoother DC output.
To further smooth the DC output, capacitors can be added to the circuit. Capacitors store and release energy, reducing the ripple effect and creating a more stable DC supply. This process is essential for many electronic devices that require a steady DC voltage.
That’s all for this lesson! To learn more, check out additional resources and videos. Stay curious and keep exploring the fascinating world of electronics!
Gather a diode, an LED, a battery, and some wires. Connect them to form a simple circuit. Make sure the cathode of the diode is connected to the negative side of the battery. Observe how the LED lights up only when the diode is correctly oriented. This hands-on activity will help you understand the concept of forward and reverse bias in diodes.
Using a set of diodes and a circuit board, try connecting diodes in different orientations. Predict whether the LED will light up based on the diode’s orientation. Test your predictions and discuss why the LED lights up or doesn’t. This will reinforce your understanding of how diodes control the direction of current flow.
Create a diagram showing both electron flow and conventional flow in a circuit with a diode. Label the anode and cathode, and indicate the direction of each type of flow. This activity will help you visualize the difference between electron flow and conventional flow, enhancing your comprehension of these concepts.
Set up a simple circuit to convert AC to DC using a diode. Use an AC power source and observe how the diode allows only one half of the AC wave to pass through. Discuss how this creates a rough DC output and explore how adding more diodes can create a full-wave rectifier for a smoother output.
Add a capacitor to your AC to DC conversion circuit. Observe how the capacitor smooths the DC output by reducing the ripple effect. Discuss why a smooth DC output is important for electronic devices. This activity will help you understand the role of capacitors in creating a stable DC supply.
Here’s a sanitized version of the provided YouTube transcript:
—
A diode looks something like this and comes in different sizes. They typically have a black cylindrical body with a stripe at one end, as well as some leads to connect it into a circuit. This end is known as the anode, and this end is the cathode. We’ll explore what that means later in this video.
You can also find other forms, such as a Zener diode or an LED, which is a light-emitting diode, but we won’t cover those in this video. A diode allows current to flow in only one direction in a circuit. If we imagine a water pipe with a swing valve installed, as water flows through the pipe, it will push open the swing gate and continue to flow. However, if the water changes direction, it will push the gate shut and prevent it from flowing. Therefore, water can only flow in one direction, which is very similar to how a diode works. We use diodes to control the direction of current in a circuit.
I’ve animated this video using electron flow, where electrons flow from the negative to the positive. However, you might be used to seeing conventional flow, which is traditional in electronics engineering, where electrons flow from the positive to the negative. Electron flow is what’s actually occurring, but you might still come across conventional currents, as these explanations can be easier to understand. Just be aware of the two and which one we’re using.
If we connect a diode into a simple LED circuit, we see that the LED will only turn on when the diode is installed the correct way. This is because it allows current to flow in only one direction. Depending on which way the diode is installed, it will act as either a conductor or an insulator. For the diode to act as a conductor, the stripe end must be connected to the negative, and the other end must be connected to the positive. This allows current to flow, and we call this the forward bias. If we flip the diode, it will act as an insulator, and the current can’t flow; we call this the reverse bias.
As mentioned, we use diodes to control the direction of current flow in a circuit, which is useful for protecting our circuit. If the power supply was connected incorrectly, the diode can block the current and keep our components safe. We can also use them to convert alternating current (AC) into direct current (DC). AC moves electrons forwards and backwards, creating a sine wave with positive and negative halves, while DC moves electrons in just one direction, resulting in a flat line in the positive region.
If we connect the primary side of a transformer to an AC supply and then connect the secondary side to a single diode, the diode would only allow half the wave to pass and block the current in the opposite direction. Thus, the secondary side of the circuit experiences only the positive half of the cycle, resulting in a rough DC circuit, although the current pulsates.
We can improve this by connecting four diodes to the secondary side, creating a four-wave rectifier. The diodes control which path the alternating current can flow along by blocking or allowing it to pass. As we just saw, the diodes allow the positive half of the sine wave to pass, but this time the negative half is also allowed to pass, inverted to create a positive half. This results in a better DC supply because the pulsating has greatly reduced.
We can still improve this further by adding some capacitors to smooth out the ripple, eventually getting it to a smooth line that closely mimics a DC supply. We’ve covered how capacitors work in detail in our previous video, so do check that out; links are down below.
That’s it for this video! To continue your learning, check out one of the videos on screen now, and I’ll catch you there for the next lesson. Don’t forget to follow us on Facebook, Instagram, Twitter, as well as visit theengineeringmindset.com.
—
This version maintains the technical content while removing any informal language and ensuring clarity.
Diode – A component that allows current to flow in only one direction. – Example sentence: The diode in the circuit ensures that electricity flows in the correct direction.
Current – The flow of electric charge through a conductor. – Example sentence: The current in the wire was measured using an ammeter.
Electricity – A form of energy resulting from the existence of charged particles. – Example sentence: Electricity powers our homes and devices through a network of wires and circuits.
Circuit – A closed loop through which an electric current can flow. – Example sentence: The engineer designed a circuit to control the lighting system.
Flow – The movement of electric charge through a conductor. – Example sentence: The flow of electrons in a conductor creates an electric current.
Anode – The positive terminal of a diode or battery where current flows in. – Example sentence: In a diode, the anode is connected to the positive side of the circuit.
Cathode – The negative terminal of a diode or battery where current flows out. – Example sentence: Electrons leave the battery through the cathode.
AC – Alternating current, where the flow of electric charge periodically reverses direction. – Example sentence: Household appliances typically use AC power from wall outlets.
DC – Direct current, where the flow of electric charge is in one constant direction. – Example sentence: Batteries provide DC power to electronic devices.
Capacitor – A device used to store electrical energy in an electric field. – Example sentence: The capacitor in the circuit helps to smooth out fluctuations in voltage.
