Introduction to Circuits

Designing and building electronic circuits can be intimidating, and fully understanding the theories behind circuit operation can take years of study. However, just as I can bake a decent loaf of French bread without having studied the biochemical interactions of yeast and sugar, I believe that anyone can build electronic circuits if they have the right cookbook. I bet it won’t even take as many tries as it took me to get my first really good loaf!

What follows is my attempt to write that cookbook for electronics, introducing components and principles with a little bit of background, but mainly recipes for how you’ll want to use them. Like a cookbook, it’s divided into “courses” for different parts of the meal; and within each section it progresses from introductory to more advanced topics.

Each “recipe” entry has a link to the full page for that recipe (or it just has plain text if I haven’t written the entry yet), then a description of what you get from it, followed by the technical version of the same information:

  • Introduction to LEDs (which end is which, using a resistor)
    [anode/cathode identification, current-limiting, source versus sink]

The technical information is there to help you find jargon terms you may have heard thrown around, and to help more experienced circuit builders find what they’re looking for quickly.

Don’t feel obligated to learn advanced LED topics before moving on to the introduction to switches! The sections are arranged so that their first recipes make a nice progression when you’re starting out, but you can come back and browse the other recipes at any time.

Also note that this cookbook is aimed specifically at the type of circuits you’d connect to a microcontroller like the LogoChip or Arduino, and not nearly as much at circuits that stand alone. If you’re interested in building a project that responds in complex ways to its environment and you already have the “brain” of your system, these recipes should help you build the eyes, ears, and hands.

Finally, if you have questions, suggestions, or general comments, or especially if you find this cookbook approach useful, I’d love to hear from you! Please use the comment form at the bottom of the page to send me whatever you have to say. I’ll try to respond by improving the cookbook, replying to you by email, or both. [Hm, WordPress pages don't have comment forms on them. I'll have to figure out what to do about that.]


  • Introduction to breadboards (how to connect components and jumper wires)
    [internal connections, jumper color coding]
  • Powering your circuit
    [passives connected to microcontroller, lab power supply, wall warts, batteries, voltage regulators]


  • Introduction to LEDs (which end is which, using a resistor)
    [anode/cathode identification, current-limiting, source versus sink]
  • Advanced LED topics (multicolor LEDs, determining resistor values)
    [tricolor, RGB, Ohm's Law]


  • Using switches with digital circuits
    [NO/NC, pullup resistors, inverted logic]
  • Using a bank of switches for configuration options
    [DIP switches with SIP resistors]


  • Reading schematic/circuit diagrams
  • Index of schematic symbols


  • Common types of motors
    [AC, DC]
  • Controlling a motor with electronics
    [relays, transistors, driver chips]
  • Advanced motor control topics (reversing, speed control)
    [H-bridge, PWM]
  • Advanced motor types
    [stepper, servo]


  • Different ways of connecting and reading sensors
    [digital, analog, A/D]
  • Light and brightness
    [CsS photocells, voltage divider]
  • Temperature
    [temperature to voltage sensor]
  • Distance
    [ultrasonic rangefinder]