555 Timer: Blink LED
Here's how to build a simple LED blinker using a 555 timer. The 555 timer is configured as an astable multivibrator, which means the output will turn on and off repeatedly. With the chosen values, it will turn on and off about five times per second. Since the LED is connected to the output, it blinks =)
The Circuit
The way the capacitor C1 and the resistors R1 and R2 are connected to the 555 timer sets it up in astable mode, which means the output will keep switching between on and off.
The values of both R1 and R2 decides how long it takes to charge C1. This time is the time the output stays HIGH.
Only the value of R2 decides how long it takes to discharge C1. This is the time the output will stay LOW.
If you want it to blink faster or slower, you can change either of the values C1, R1, or R2. Check out this 555 Timer Calculator to see how the values affect the output.
Parts List
The Layout
Below, you can see an example of how you can lay this LED blinker circuit out on a breadboard. Check out this 555 Tutorial to learn how to design lots of fun circuits with the 555 Timer.
