LED Flasher with LM3909

By | December 21, 2009

This is a very easy and simple LED flasher with only three components: a flasher IC LM3909, a LED indicator and an electrolytic capacitor.

LED Flasher with LM3909

The supply voltage is 1.5V, so it can be operated using a 1.5V battery which can be easily found on market.

Component list:

LED1 _________ Red LED
C1 ___________ 100uf/16V
IC1 __________ LM3909
Battery ______ 1.5V AAA

The LM3909 is a monolithic oscillator specifically designed to flash Light Emitting Diodes. By using the timing capacitor for voltage boost, it delivers pulses of 2 or more volts to the LED while operating on a supply of 1.5V or less. The circuit is inherently self-starting, and requires addition of only a battery and capacitor to function as an LED flasher.

This circuit can be used for various applications:

  • Finding flashlights in the dark, or locating boat mooring floats
  • Sales and advertising gimmicks
  • Emergency locators, for instance on fire extinguishers
  • Toys and novelties
  • Electronic applications such as trigger and sawtooth generators
  • Siren for toy fire engine, (combined oscillator, speaker driver)
  • Warning indicators powered by 1.4V to 200V
LED Flasher with LM3909 was last modified: September 25th, 2014 by circuit diagram

Scheme related to LED Flasher with LM3909:

LED Flasher 2-Transistors The following is LED Flasher circuit which use 2 transistors for LED switching. The circuit works similar to flip-flop operation. Components List: R1 = 10M ohm R2 = 1K - 100K ohm R3 = 470 ohm C1 = 0.47μF - 10μF/25V D1 = 1N914 Q1 = ...

One thought on “LED Flasher with LM3909

Leave a Reply

Your email address will not be published. Required fields are marked *