How to make a blinking LED with a 555 timer IC

Picture of How to make a blinking LED with a 555 timer IC
This Instructable will show you how to make a blinking LED with a 555 timer IC on a breadboard, view the attached video to see it in action.

Remove these adsRemove these ads by Signing Up

Step 1: Materials

Picture of Materials
You will need:
1 Breadboard
1 9V battery
1 9V battery connector
1 Capacitor, I am using a 47μF, the higher the number the slower it will blink, 47 works good.
2 resistors, a 10K and a 150Ω
1 +5V voltage regulator
1 555 timer IC
Assorted jumper wires
Space to work

Step 2: Mount the IC

Picture of Mount the IC

Take your 555 timer and find the small dot (picture 1) Make sure that dot is in the top left corner, then mount it in the board. The dot needs to be in the top left so we can know what pin is where. Push the chip in until it stops.

Step 3: Wire up the IC

Now, we want to connect Pin 1, to ground. Pin 8, to +9V.And Pin 2, to Pin 6.

Step 7: Resistors

Take your 150 and 10K Ohm resistors, and put the 10K from pin 6 to pin 7. Then the 150 Ohm from pin 7 to positive. If you put the 10 K from 7 to positive, and the 150 from 6 to 7, you will get a much slower blink.
dragon175 months ago

I have one doubt. What is the use of the capacitor here and how it works in dc that you are providing?

texpert1 year ago
if you wanted to change the rate at which the led flashes, so like it would be adjustable, could you replace the resistors with potentiometers? or do you think you would just have to change the value of the capacitor to achieve this?
hi.. i want to blink 40 + LED's, for that what i have to do?...

if i Connects all the LED's in parallel and connect to ur given broad... it will works fine or not?... Please suggest the best way to achieve it...
Techno Dude2 years ago
why do we need a 5v regulator
Weldeon (author)  Techno Dude2 years ago
We are giving the circuit 9v, when the 555 is designed for 5.
Sorry but I thought that I read somewhere that the 555 is a versatile 5-15v IC. Correct me if I'm wrong. Anyway, very nice Instructable!
i Think u can use LM317 as voltage regulator that gives 5v output :)
Weldeon (author)  kevrack19992 years ago
Huh, well dang, I had read everywhere that you should restrict it to 5, but my package says 18V max. Thanks for clearing that up. I'm just used to using a reg.
taz99taz2 years ago
Pin 4 must be connected to pin 8 if u want to make a blinking LED :D
ianlee742 years ago
I'm very frustrated. I've tried yours as well as several similar examples on the internet and all my LED does is light up w/o ever blinking. Would could I be doing wrong? I didn't have a voltage regulator to use but my 555 says its rated for 18V so that couldn't be it, right? None of the other examples I've tried used the regulator. Any insight you might have would be appreciated. Thanks!
Weldeon (author)  ianlee742 years ago
Mine did this at first as well, it was either the capacitor or the resistors. make sure you have the 150 Ohm resistor is connected to positive and not negative, that was a problem for me sometimes.
Also, sometimes the resistors and capacitors refused to connect in the breadboard well enough to register, which in turn caused it not to blink. Verify all connections, and if it still doesn't work, it is possible that your 555 is faulty, just letting electricity fly through, instead of doing it's job.

Best of luck
By any chance do you have a schematic?
Weldeon (author)  Computothought3 years ago
Just put one up for ya, if its not good enough, there are tons out on the internet you can find easily with google.
Thank you.