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555 Timer LED Blinker (No Code)

Blink an LED with a classic 555 timer in astable mode — pure hardware, no microcontroller code.

Beginner25 min

What you need

Wiring

Arduino Uno
NE555
LED

Hover a pin or a wire to trace the connection.

Code

555 astable — component values (no firmware)
No firmware — the 555 oscillates on its own.

R1 = 10 kΩ, R2 = 47 kΩ, C1 = 10 µF

Blink rate ≈ 1.44 / ((R1 + 2*R2) * C1) ≈ 1.4 Hz
On-time   = 0.693 * (R1 + R2) * C1
Off-time  = 0.693 * R2 * C1

Bigger C1 or R2 -> slower blink. The Arduino here is only a 5V supply;
you can use any 5V source.

Steps

  1. Power the 555: pins 8 and 4 to +5V, pin 1 to GND.
  2. R1 from +5V to pin 7; R2 from pin 7 to pin 6; jumper pin 6 to pin 2.
  3. C1 from pin 2 to GND (watch polarity on the 10µF).
  4. Pin 3 (OUT) to the LED through a 220Ω resistor; cathode to GND. It blinks ~1.4×/sec.