555 Timer LED Flasher

About: Hi! I'm Dave, and I've lived in China for about three years now. As my username suggests, I'm from California, so naturally, I miss the sunshine, the beaches, and the crisp evening air. In my spare time, I...

The first project I ever built was a light that blinked on and off. It took nine parts and a couple of wires. Nice and easy.

Using some resistors and capacitors, I basically configured a 555 timer chip to act as an oscillator (fancy term for something that generates electrical pulses at regular intervals). I used the pulses to drive an LED, which turned on whenever there was a pulse and turned off whenever there wasn't a pulse (thus the blinking action). In technical terms, this circuit is called an "astable multivibrator."

This is a great project to start off with if you're thinking about doing electronics. Here's what you'll need:

-U1: 555 Timer IC
-R1: 1 megohm potentiometer
-R2: 47 kilohm resistor
-R3: 330 ohm resistor
-C1: 1 µF electrolytic capacitor
-C2: 0.1 µF (100nF) disc capacitor
-LED: 5mm red LED
-9V battery
-Solderless breadboard

Just assemble the circuit according to the attached schematic diagram (555 LED flasher.pdf), and you're set. For a nice explanation of how this actually works, visit the Electronics Club's 555 Timer page here.

Note: A month ago, I made an improvement to my original design that allows me to drive two LEDs instead of just one. Basically, the LEDs are connected so that whenever there is a pulse from the 555 timer, the red LED turns on and the green LED turns off, and whenever there isn't a pulse, the green LED turns on and the red LED turns off. I have included the corresponding circuit diagram (LED Flasher 2) with this Instructable.



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8 Discussions


5 years ago on Introduction

hi .i want help to make car voltage input 12 high power red led ....F1 style falsher ......like the Link below .....http://www.youtube.com/watch?v=J964lGezvMk.........or ........can u help me guys.........i want this for my punto.........i am using the style of leds like this ..........5 ...OOOOO
...............................4.... OOOO
...............................3......OOO..............Can u please share the circuit diagram of it....


6 years ago on Introduction

sorry if this is a dumb question but how do you connect the potentiometer in this?


6 years ago on Introduction

I have a ? instead of using an led could i use a automotive relay and have it work? also would i be able to hook it up to the car battery instead of the 9V?


7 years ago on Introduction

now i assume they flash but do they have a strobe effect? and how would i turn this into a 12v system? thanks

Basem Salep

7 years ago on Introduction

My firist project was a flasher but not like this i used 2 transistors pnp
4 resistors 2 capacitors 2 leds
in your circuit the 2 leds lighting and close in the same time ??

1 reply

Don't be fooled by the picture! :)

When the red LED is on, the green LED is supposed to be off; when the green LED is on, the red LED is supposed to be off. When I took the picture, this happened too fast for the camera to capture, so it appears as if the two LEDs turn on and off at the same time.