The 555 timer: one chip that blinks
How a 555 timer chip, two resistors and a capacitor make an LED blink on its own (astable mode) — no Arduino needed.
Can you blink an LED with NO code? Yes — with a 555 timer! ⏱️💡
1️⃣ THE PARTS: one NE555 chip + 2 resistors + 1 capacitor. It blinks by itself (runs on 4.5–15 V — a 9 V battery is perfect).
2️⃣ THE CAPACITOR: it charges up to 2/3 of the supply through R1 + R2, then the chip drains it down to 1/3 through R2 (pin 7). Again and again!
3️⃣ THE SPEED: while it charges, pin 3 is HIGH and the LED is on. Change the parts to change the speed: f ≈ 1.44 ÷ ((R1 + 2·R2) × C).
With R1 = 1 kΩ, R2 = 68 kΩ, C = 10 µF → about 1 blink a second. Swap in 1 µF → about 10 a second.
One chip, one blink!
Read the voiceover (transcript)
- Blink an LED with no code?
- Meet the five-five-five! Two resistors and a capacitor, and it blinks by itself.
- The capacitor charges up to two thirds, then the chip drains it to one third. Again and again!
- While it charges, the LED is on. Change the parts to change the speed.
- One chip, one blink!
- Next: make it beep! Follow for part thirteen!
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