skills
The ideas behind every circuit.
A handful of ideas keep showing up — circuits are loops, Ohm's law, voltage dividers. Learn one and half a dozen projects suddenly make sense. Each page below shows what the idea means and lists the projects that put it to work.
Circuits are loops Electricity only flows around a complete, unbroken loop. LED polarity LEDs are one-way doors: long leg to plus, or nothing happens. Ohm's law Voltage = current × resistance. One equation, endless circuits. Series & parallel Parts in a chain share voltage; parts side-by-side share current. Switches Breaking and completing loops on purpose — the root of all control. Voltage dividers Two resistors split a voltage — the trick behind almost every sensor. Transistor switching A tiny current at the base opens a gate for a much bigger one.
Prefer to learn by building? Start at Projects — every project lists the ideas it teaches, right under its parts list.