74HC4017 Decade Counter LED Runner

Ten LEDs light up one after another in a tidy parade, driven by a CMOS decade counter — the classic chip used in everything from disco bar graphs to the first LED dice projects.

Difficulty: Breadboard. Estimated build time: about 30 minutes. Estimated parts cost: about US$4.60. 8-part bill of materials with live supplier pricing. A 10-LED running-light strip clocked by a 74HC4017 decade counter.