Build a 555 Timer LED Flasher: A First Project for Beginners

The 555 timer has been a favourite first IC for decades. In this project you will wire it as an oscillator that blinks an LED about once per second.

What you need

• NE555 timer IC
• 10 µF electrolytic capacitor
• 10 nF ceramic capacitor
• 1 kΩ, 68 kΩ and 470 Ω resistors
• One LED
• Breadboard, jumper wires and a 5–9 V supply

How it works

In astable mode the 555 charges and discharges the capacitor between one-third and two-thirds of the supply voltage, flipping its output each time. The frequency is approximately 1.44 / ((R1 + 2 × R2) × C). With R1 = 1 kΩ, R2 = 68 kΩ and C = 10 µF you get about 1 Hz — one blink per second.

Wiring

1. Connect pin 1 to ground, and pins 4 and 8 to the positive supply.
2. Place R1 (1 kΩ) from the supply to pin 7, and R2 (68 kΩ) from pin 7 to pin 6.
3. Join pins 2 and 6, then connect the 10 µF capacitor from pin 2 to ground (negative leg to ground).
4. Put the 10 nF capacitor from pin 5 to ground for stability.
5. Connect pin 3 → 470 Ω resistor → LED anode, and the LED cathode to ground.

Try next

Swap the 10 µF capacitor for 1 µF to blink ten times faster, or drive a small buzzer from pin 3 to turn the flasher into a beeper.