Simple led flasher circuit using 555 timer IC


This is a simple led flasher circuit using a 555 timer IC. It's one of the simplest circuits you can build and is certainly a beginners project. The circuit diagram is shown below and I've included instructions to build it even if you don't understand circuit diagrams.

The circuit diagram for a simple led flasher circuit using a 555 timer IC.

The circuit is built on a single IC prototype board. These are commonly available from component suppliers. I think I got mine from the high street shop Tandy. As you can see I've used it before so I've de-soldered components from it and cleaned it up a bit.

First step is to solder the 8 pin IC socket in the position shown above.

Next step is to solder two wire links as shown above. Pin 2 to pin 6 and pin 4 to pin 8.

Next step is to add the 1K resistor between pins 7 and 8. A 4.7uF capacitor is then soldered between pins 1 and 2. Be careful to make sure you solder this one in the correct way round with the capacitor's negative going to pin 1.

Next step is to solder two wires to the 1M variable resistor, one to the centre and one to an end connection.

The other ends of the wires from the variable resistor should be soldered to the positions shown above. Note it doesn't matter which wires go where on this occasion.

The 0.01uF capacitor needs to go between pins 1 and 5 if you check the circuit but it easier and tidier to solder it pin 5 and the vacant strip underneath it, then put a wire link from that to pin 1 as you can see in the picture above. 

The last steps are to solder the battery clip on to the board. The black lead goes to pin 1 and the red lead goes to pin 8. You may have noticed that the circuit shows 5V on it but we are using a 9V battery, in this circuit it doesn't matter as it will quite happily run on anything between 5V and 15V. The only other thing to do is to mount the LED and current limiting resistor, that's the 330R one. The LED needs to be used the correct way round. Find the cathode, which is usually marked by a flat line on the side of it and solder that to one end of the 330R resistor. Then solder the other end of the LED to pin 3 and the other end of the resistor to pin 1.  

Here is a clearer picture of the 330R resistor soldered to the LED and board. Once you have finished this you can plug the 555 timer chip into the socket. Make sure pin 1 is at the top left, it's marked with a small dot or the top of the chip is indented. Connect the battery onto the clip and the LED should start flashing away. Turning the variable resistor will speed up or slow down the rate of the flashing from quite a slow rate to too quick for the eye to see.  

I've included a short video clip below so you can see the board functioning for yourself.

This simple led flasher circuit using 555 timer IC is easily assembled by a total beginner. hopefully if you have accurately followed all the steps here you now have a fully functioning circuit.