Create a Flashing Lights Circuit With a 555 Timer and a Relay





Introduction: Create a Flashing Lights Circuit With a 555 Timer and a Relay

I'm gonna you how to make a alternating pulsating circuit (using 555 timer) to run a relay.
Depending on the relay you may be able to run 120vac light.
It does not alternate that good with small capacitor(I will explain later on).

Step 1: What You Will Need.

-1 5 pin relay (5 vdc)
-Ceramic capacitor(For reducing arcing on the relay)
-1 red LED(optionnal)
-1 green LED(optionnal)
-2 110 ohm resistor(to go with LED)
-10 to 1000 uf electrolitic capacitor
-2 1k ohm resistor
-1 555 timer
-perf board
-soldering iron
-wire cutter

Step 2: The Circuit

The red LED is to indicate power and the green LED is to show the speed that it is pulsing at.
I would suggest using a 330 uf electrolytic capacitor(this capacitor will determent the speed at witch the relay is pulsing the bigger the capacitor the slower the pulsing).
(Small capacitor don't alternate good, they don't give anoff time for the light to stay on.)

Step 3: Now Your Done!

I would suggest putting this in a project box.
You can pulse lights, motor and other ,anything you relay can withstand.



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Questions & Answers


Hi Steven, Thanks for the great instructable. Could You tell me how to modify this circuit? I'm using this for a sequential tail light flasher. I need the relay to stay on 3 seconds and off 1 second. I'm assuming just changing cap values changes the both on and off. Thanks in advance

I am planning to buld a 10 x 3W amber led bulb night rider type system, with 5 on each side of my 4x4.
Could anyone help by suggesting a good layout as Im kind of new to all this but keen to learn.
I am planning to use a 9V battery by the way.


Here is the circuit you will need to use:
You will need to add transistor where the LEDs are to power your 3watts LEDs.
I wont tell you how to put the transistors in that circuit do some reasurch on how they work (many good site out there) (here a hit use NPN type transistors)
A 9volt battery wont have the power for your circuit use the vehicles power.
Good luck!

Hi foxtrotbravoone,

did you build your 'Knight Rider' lights on your 4x4?
Would like to hear about the circuit you used.

If you still interested in building it, let me know.
I have some ideas.


oye como elecrtonico no se,pero como dibujante jejejeje uffffffff.....

try this circuit (but made it for 12V) or do the needed changes This can carry more leds (due to 12V)

i need to learn 15 led

 might works if you put them in parallel...I assume you want to make a "knight Rider" flash light???

thanx for the instructable! question: can you do this with a bunch of LEDs? you know like making a ring of flashing lights, one lights up at a time.

LED Chaser?? If so, this circuit can't but there are many on the net.