Introduction: 555 Timer LED Flasher

Picture of 555 Timer LED Flasher

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.


juiceman74 made it! (author)2017-02-21

Thanks for the post. I've built the circuit, and used a 0.1uF (100pF, I think) reset capacitor instead of a 10 pF, as recommended. It works like a charm flashing about every second or less. Now I'm going to built it on PCB and hopefully turn it into a kids flashing game.

shreyas2308 (author)2013-06-17

hi .i want help to make car voltage input 12 high power red led ....F1 style falsher the Link below ..... ........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....

shreyas2308 (author)2013-06-17

oderflaful (author)2013-05-30

i have leaned plenty instructions on this site. thanks

mabster925 (author)2013-02-23

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

Steger1977 (author)2012-09-28

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?

12amedle (author)2012-02-17

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 (author)2011-12-29

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 ??

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.

About This Instructable




Bio: 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 ... More »
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