7. Electronics design¶

AC vs DC: Key Differences¶

What is AC (Alternating Current)?¶

AC reverses direction periodically and is used in power grids, homes, and appliances. It can be easily transformed to different voltages, making it ideal for long-distance transmission.

Advantages of AC:¶

Efficient for long-distance power transmission.
Easily converted to different voltages.

What is DC (Direct Current)?¶

DC flows in one direction and is used in batteries, electronics, and solar panels. It provides a stable voltage for sensitive devices.

Advantages of DC:¶

Stable for electronics and batteries.
Ideal for renewable energy systems.

AC vs DC Comparison¶

Both AC and DC are essential, with AC powering homes and DC running electronics.

Components¶

Resistor¶

Definition¶

A resistor is an electronic component that limits or regulates electrical current in a circuit. It is one of the most fundamental components in electronics.

How Does a Resistor Work?¶

• A resistor reduces the flow of current by providing resistance.
• The resistance is measured in ohms (Ω).
• It follows Ohm’s Law:
  [ V = I \times R ] where V is voltage, I is current, and R is resistance.

Types of Resistors¶

• Fixed Resistors – Have a constant resistance value.
• Variable Resistors (Potentiometers) – Adjustable resistance.
• Thermistors – Change resistance with temperature.
• LDR (Light Dependent Resistors) – Change resistance based on light intensity.

Resistor Color Code¶

Most resistors use a color code to indicate resistance value. Each color represents a number, following a standard coding system.

Applications of Resistors¶

✔ Current limiting in circuits.
✔ Voltage division.
✔ Signal filtering in audio and radio circuits.
✔ Temperature and light sensing.

Conclusion¶

Resistors are essential in electronics, controlling current flow and protecting components from excessive voltage and current.

Capacitor¶

Definition¶

A capacitor is an electronic component that stores and releases electrical energy in a circuit. It consists of two conductive plates separated by an insulating material (dielectric).

How Does a Capacitor Work?¶

• When a voltage is applied, the capacitor stores electrical charge on its plates.
• When the circuit requires energy, the capacitor releases the stored charge.
• The capacitance is measured in farads (F).

Types of Capacitors¶

• Ceramic Capacitors – Small and used in high-frequency circuits.
• Electrolytic Capacitors – High capacitance, used in power supplies.
• Tantalum Capacitors – Stable and compact.
• Film Capacitors – Reliable for filtering and audio applications.
• Supercapacitors – Store large amounts of energy.

Capacitor Applications¶

✔ Energy storage in power circuits.
✔ Filtering in power supplies to smooth voltage.
✔ Coupling and decoupling signals in audio and RF circuits.
✔ Timing circuits for oscillators and frequency generation.

Conclusion¶

Capacitors are essential in electronics, used for energy storage, filtering, and signal processing. They play a crucial role in almost every electrical device.

LED¶

Definition¶

An LED (Light Emitting Diode) is a semiconductor device that emits light when an electric current flows through it. LEDs are energy-efficient and widely used for lighting and display applications.

How Does an LED Work?¶

• LEDs function based on the electroluminescence principle.
• When current passes through the LED, electrons recombine with holes in the semiconductor material, releasing energy in the form of light.
• The color of the light depends on the semiconductor material used.

Advantages of LEDs¶

✔ Energy-efficient – Consumes less power than traditional bulbs.
✔ Long lifespan – Can last 50,000+ hours.
✔ Fast switching – Instantly turns on and off.
✔ Compact size – Suitable for small electronic devices.
✔ Variety of colors – Available in multiple wavelengths.

Types of LEDs¶

• Standard LEDs – Used in indicators and displays.
• High-Power LEDs – Bright and used in lighting applications.
• RGB LEDs – Emit different colors by combining red, green, and blue light.
• Infrared LEDs (IR LEDs) – Used in remote controls and sensors.
• UV LEDs – Used in sterilization and medical applications.

LED Applications¶

✔ Lighting – Streetlights, home lighting, and automotive headlights.
✔ Displays – TVs, monitors, and digital billboards.
✔ Indicators – Used in electronics and control panels.
✔ Communication – Fiber optics and remote controls.
✔ Medical & Industrial Use – UV sterilization and infrared sensors.

Conclusion¶

LEDs are an essential component in modern electronics due to their efficiency, longevity, and versatility. They have replaced traditional lighting technologies in many applications.

Transistor¶

Definition¶

A transistor is a semiconductor device used to amplify or switch electrical signals. It is one of the most fundamental components in modern electronics.

How Does a Transistor Work?¶

• A transistor controls the flow of current using a small input signal.
• It has three terminals:
• Base (B) – Controls the transistor.
• Collector (C) – The main current input.
• Emitter (E) – The main current output.
• Small current at the Base can control a much larger current between the Collector and Emitter.

Types of Transistors¶

• Bipolar Junction Transistor (BJT) – Uses small current at the base to control a larger current.
• Field-Effect Transistor (FET) – Uses voltage instead of current to control the flow.
• MOSFET (Metal-Oxide-Semiconductor FET) – Common in digital circuits and power electronics.

Applications of Transistors¶

✔ Switching – Used in microcontrollers, logic gates, and digital circuits.
✔ Amplification – Used in audio systems, radios, and signal processing.
✔ Voltage Regulation – Used in power supplies and battery chargers.
✔ Oscillators – Used in timers and frequency generators.

Conclusion¶

Transistors are essential building blocks of modern electronics, enabling everything from computers and smartphones to power circuits and amplifiers.

Measuring devices¶

Multimeter¶

✔ They measure voltage and current.
✔ The black cable should always be ground.
✔ For DC signals, the multimeter is perfect.
✔ For signals that alternate, multimeter is not the best tool — multimeter will average out readings.

Oscilloscope¶

X and Y axis visualizations of a current, shown on a screen that's divided into squares, whose values can be adjusted in order to help better visualize the current.

NB. Always connect the ground first with any measuring tool.

KiCad¶

KiCad is a free and open-source software suite for electronic design automation (EDA). It allows users to create schematic diagrams and design printed circuit boards (PCBs).

Key Features¶

• Schematic Capture – Design and connect electronic circuits.
• PCB Layout Editor – Create multi-layer PCB designs.
• 3D Viewer – Visualize and inspect PCB designs in 3D.
• Gerber File Export – Generate files for PCB manufacturing.
• Autorouter & Manual Routing – Flexible PCB trace routing.
• Cross-Platform – Available for Windows, macOS, and Linux.

Why Use KiCad?¶

✔ Free and Open-Source – No licensing fees, fully community-supported.
✔ Unlimited PCB Layers – Unlike many free EDA tools, KiCad allows complex designs.
✔ Large Library Support – Extensive components and footprints.
✔ 3D Model Integration – Supports 3D rendering for PCB visualization.
✔ Active Community – Regular updates and user contributions.

Workflow in KiCad¶

1. Create a Schematic (Eeschema)
2. Add components and wire connections.

3. Assign footprints to components.

4. Design the PCB (Pcbnew)

5. Arrange components on the board.

6. Route electrical traces manually or use the autorouter.

7. Generate Manufacturing Files

8. Export Gerber files, drill files, and BOM (Bill of Materials).

9. 3D Preview & Final Adjustments

10. Check the design in the 3D Viewer.
11. Optimize layout for better signal integrity and manufacturability.

KiCad Applications¶

• Hobbyist PCB Projects
• Professional Circuit Design
• Open-Source Hardware Development
• Educational Use in Electronics & Engineering

Conclusion¶

KiCad is a powerful, free, and flexible PCB design tool suitable for both beginners and professionals. With its rich feature set and active community, it is a great alternative to proprietary EDA software.

My first pcb design¶