Light and LEDs Overview

Light and LEDs

• Light is energy released by atoms in packets called photons.
• Photons are released due to moving electrons.
• Visible light emission from a diode depends on its material composition.
• Aluminum-Gallium-Arsenide (AlGaAs) is a conductor material used in LEDs that emit visible light.
• Standard Silicon (Si) diodes emit infrared (IR) light, invisible to the human eye but useful in remote controls.
• The color of an LED is determined by its conductor/doping materials.

LED Advantages over Incandescent Bulbs

• LEDs run cooler, generating little heat.
• LEDs are more efficient, brighter per watt, meaning more power is used for light generation.
• LEDs are more durable with hard plastic casings and lack delicate filaments.
• LEDs are smaller, fitting easily into modern circuits.
• LEDs have longer lifespans (50,000 hours or more).
• LEDs are more cost-effective due to lower power needs and fewer replacements.

Transistors

• Transistors are more complex semiconductor devices than diodes.
• The name derives from "transfer of resistance".
• Transistor uses include switching (high and low power applications) and amplification.
• Types include Bipolar Junction Transistors (BJTs), Field Effect Transistors (FETs), Junction FETs (JFETs), Insulated Gate FETs (IGFETs), and Metal-Oxide-Semiconductor FETs (MOSFETs).

Transistor Operation

• A BJT resembles two back-to-back diodes: Base (B), Collector (C), Emitter (E). NPN has two N-type layers around a P-type layer, PNP is the reverse. They are normally OFF, turning ON with sufficient base current.
• A JFET is analogous to a hose with a clamp: Gate (G), Source (S), Drain (D). The Drain-Source is the current path; the Gate controls current flow. JFETs are normally ON, turning OFF with sufficient gate voltage.

Integrated Circuits (ICs)

• ICs are extremely sensitive to heat, movement, and voltage spikes.
• Handle ICs carefully, using sockets to avoid heat damage and grounding oneself to prevent voltage spikes.

Other Electronic Components

• Many other components exist, categorized as passive/active and analog/digital.
• Examples include connectors, bells/buzzers, phototransistors/photodiodes, microphones, fuses, varistors, thermistors, antennas, transformers, gates, motors, and meters.

Inductors

• Inductors use electric current through a coil to create magnetism.
• Inductance is the electromotive force (EMF) generated by current changes.
• Iron and ferrite cores increase inductance. Ferrite cores are brittle.
• Inductors block AC signals and pass DC signals (opposite of capacitors).
• Uses include tuned circuits (e.g., radio receiver tuning coils). Also called solenoids (when wound on a ferrite core) or chokes (when used to block high-frequency AC).

Diodes

• Diodes are simple semiconductor devices.
• Semiconductors are materials with variable electrical conductivity.
• Diodes are made from poor conductors with added impurities ("doping").
• N-type material has extra electrons; P-type material has extra holes.
• A diode has bonded N-type and P-type materials, conducting electricity in one direction only.

Light Emitting Diodes (LEDs)

• LEDs produce light when current passes through the diode, exciting electrons and causing the emission of photons. The energy of these photons determines the color.

Explore the fascinating world of light and LEDs in this quiz. Discover how LEDs work, their advantages over traditional incandescent bulbs, and learn about the materials involved in their construction. Test your knowledge on the science of light and semiconductor technology.