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ComponentsšŸ”—

Circuit Foundations explains what electricity does. This topic is about the parts you actually hold: what's inside each one, how to read its markings, and how to choose the right one from a datasheet.

The articles build on Circuit Foundations, especially Ohm's Law and Power, and each one stands on its own.

Components reading order, as a transit map One line through seven stops in three stages. Resistors: Color Codes, Resistor Types; Valves for current: Diodes and LEDs, Transistors, Vacuum Tubes; Sensors and packages: Temperature Sensors, Package Types. Every stop is a link to its article. Click any stop to open its article Resistors Valves for current Sensors and packages 1. Color Codes 1 Color Codes 2. Resistor Types 2 Resistor Types 3. Diodes and LEDs 3 Diodes and LEDs 4. Transistors 4 Transistors 5. Vacuum Tubes 5 Vacuum Tubes 6. Temperature Sensors 6 Temperature Sensors 7. Package Types 7 Package Types
The reading order as one line. Every stop is a link.

1. ResistorsšŸ”—

2. Valves for CurrentšŸ”—

  • Diodes and LEDs ā€” one-way valves for current, why every LED colour needs its own voltage, and sizing an LED's resistor
  • Transistors ā€” small currents controlling large ones, as switches and amplifiers
  • Vacuum Tubes ā€” the glass-and-vacuum amplifier the transistor replaced, and why it's still made

3. Sensors and PackagesšŸ”—

  • Temperature Sensors ā€” three ways to turn heat into something a circuit can read
  • Package Types ā€” through-hole and surface-mount, and why a part's shape decides whether it fits a breadboard

Where to StartšŸ”—

If you're building circuits from this site, start with Resistor Color Codes: every circuit here uses resistors, and the bands are the first thing to learn to read. If an LED or a transistor is what brought you here, each of those articles stands on its own.