Introduction: Dual LED Flasher

Picture of Dual LED Flasher

Here is a simple circuit that flashes 2 LEDs alternately. It only uses a few basic components, so why don't you try it!

Step 1: Gather the Parts Needed.

Picture of Gather the Parts Needed.

Parts list:

  1. 2N3904 transistors x2
  2. 10µf caps x2
  3. Red LEDs x2
  4. 470Ω resistors x2
  5. 100kΩ resistors x2
  6. Assorted jumpers
  7. A breadboard
  8. 9V battery
  9. 9V battery clip

Step 2: The Schematic Diagram.

Picture of The Schematic Diagram.

Follow the schematic diagram for this circuit.

Step 3: Insert the Transistors and Resistors.

Picture of Insert the Transistors and Resistors.

Insert the 2 transistors in your breadboard like the one on the picture. Then, connect the emitters of the 2 transistors to the ground(negative) rail.

Connect the 2 100kΩ resistors to the bases of the transistors and the other end to a free rail.

Connect the 470Ω resistors to the collectors of the transistors and the other end to a free rail.

Step 4: Insert the Caps.

Picture of Insert the Caps.

Insert the 2 capacitors as shown in the picture. Put the negative side of the caps on a free rail on the breadboard.

Step 5: Jumpers and LEDs...

Picture of Jumpers and LEDs...

Place jumpers as shown and noted in the pictures.

Connect jumpers from the positive rail of breadboard to the 100kΩ resistors.

Step 6: Connect the Battery.

Picture of Connect the Battery.

Connect the battery to its respective rails and see if it blinks.

Congratulations, you have made your project!


tomatoskins (author)2015-05-15

I love little electronics projects like this!

fifty_ohms (author)tomatoskins2015-05-16

Thanks for your comment! I love simple projects like this!

fieryfredo made it! (author)2016-04-09

Great, thank you.. was looking for a simple circuit to make a dummy alarm box led circuit from.. I wanted to run at 3V so I removed the 470 reisistors and changed to a 100 cap to slow them down again.. I'm using LED's with 2.7V forward voltage so should be ok.

Ploopy (author)2015-07-19


tabi66 made it! (author)2015-05-24

its my project i m ist year computer engineering student...

tabi66 (author)2015-05-24

i made it thanks bro!

pfred2 (author)2015-05-16

This is the same circuit as this:

But it is a classic. This reminds me to check and see if someone else hasn't posted the circuit I'm thinking about posting here next. Yup, it's been covered. So I don't need to bother.

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