Your First Circuit: A Blinking LED

Put every earlier lesson to work in one small, satisfying build.

This circuit uses a 555 timer chip to flash an LED on and off — a classic first project that touches power supply, resistors, a capacitor, and an LED all at once.

• Parts: one 555 timer IC, two resistors (1kΩ and 10kΩ), one 10µF capacitor, one LED with a 220Ω series resistor, a breadboard, and a 9V battery with clip.
• What's happening: the resistors and capacitor set a charge/discharge timing rhythm; the 555 chip watches that rhythm and switches its output pin on and off in step, driving the LED.
• To experiment: swap the capacitor for a larger or smaller value and watch the blink rate change — a direct, visible link back to Lesson 7.

From here, every later project is a variation on the same loop: understand what each part does, build it on a breadboard, measure it, then make it permanent.