How to make a flashing LED

The LED's are environmentally friendly lighting devices, which tend to reduce the energy consumption of the devices they are connected to. Flashing LED's (5mm diameter), however, consume approximately 2 volts of direct current, which is not a very economical solution if you want to make a home alarm or a device with flashing lights. The solution is to make our own LED energy-saving flasher, from an LED fixed. In this article, we will look at how to make a flashing LED in just a few steps and with only one AA battery as a power source.

Assembly of a domestic LED flasher powered by a AA battery


To make our flashing LED, we will need the following materials:

- One 1.5V AA battery.

- An LED emitting the desired colour.

- A 150 μF, 6V capacitor.

- A National Semiconductors LM3909 integrated.

- Cables for connection.

Creating our flashing LED

We will begin by identifying each of the legs of the integrated circuit to find out where to make the connections. Remember that the integrated circuits come with a factory mark that indicates which is the first connection, from this, the numbering ascends from left to right, that is to say, in a clockwise direction.

After identifying all the connection pins on the board, we connect pins 4 and 5 to the AA battery, using wires and a small soldering iron.

Electrical circuit of the LED flasher to be constructed

Now, we connect the capacitor using the connector pins 2 and 8 of the integrated circuit. Then, we make a connection from the same output of the connector 8 of the integrated to the arrowhead connector of the LEDwhile the free connector of the LED will be connected to connection 6 of the integrated circuit. In this way, we will finish the circuit and we will be able to observe how our little light blinks using a simple and cheap power supply.

The circuit we have created allows approximately one blink per second, which makes it ideal for use in any type of electrical assembly that requires this type of light indicators.

Also, we can point out that this circuit is very low power consumption and the battery can power it for about a year without needing to be replaced. If we wish to control the shutdown of the circuit, we can insert a small switch to turn the circuit on and off. LED whenever we wish.

11 thoughts on “Cómo hacer un LED intermitente”

  1. my question is as follows 
    We have a fixed illuminated led, how could it be made to flash after a short burst of light? 
    greetings and thank you very much 

  2. daniel lema andrade

    mi amigo practico gusto aplaudo tu trabajo muy bueno...lo utilizo quedo papelito como decimos aqui..bien

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