LED Flasher with LM3909

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

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
circuit diagram

View Comments

Share
Published by
circuit diagram

Recent Posts

Guitar Synthesizer Schematic Diagram Collection

Guitar Synthesizer Schematic Diagram In this post, we provide a collection of schematic diagrams of…

54 years ago

Handy Talky HT DIY Schematic Diagram

Handy Talky Schematic Diagram This is an old electronic scheme of the Handy Talky (HT)…

54 years ago

Doorbell Ringer Birdie Tone

This is an old or "very old" schematic diagram of birdie tone or sound generator.…

54 years ago

200W MOSFET Amplifier based IRFP250N

Here is the 200W MOSFET amplifier powered based on four piece of IRFP250N, they are…

54 years ago

300W RMS Stereo Power Amplifier based IC TDA7294

This is the 300W RMS stereo power amplifier circuit project. This amplifier is based four…

54 years ago

Stereo Tone Control with Line In + Microphone Mixer

This is an active stereo tone control circuit using very well known op-amp IC of…

54 years ago