1.5V LED Flasher Oscillator


Posted on Feb 5, 2014

The 8-lead plastic mini-DIP LM3909 IC was developed by National Semiconductor in the mid `seventies of the past century. It was a monolithic oscillator specifically designed to flash Light Emitting Diodes. By using the timing capacitor for voltage boost, it delivered pulses of 2 or more volts to the LED while operating on a supply of 1. 5V or less.


1.5V LED Flasher Oscillator
Click here to download the full size of the above Circuit.

The circuit was inherently self-starting, and required addition of only a battery and capacitor to function as an LED flasher. Unfortunately, since 1998, the manufacturer discontinued the production of this chip. For this reason, and on request of some correspondents, I tried to emulate this IC operation using common discrete components, obtaining unexpected satisfactory results.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

RS485-like multi-drop bus
Self-powered Doorbell
Scanner Voice Squelch
led sequencer chaser ne555 4017
Scmitt Trigger circuit using NE 555
Sinewave Oscillator
Analog video switch and amplifier with direct coupled output
Ultra High Sensitivity Metal Detector Circuit



Top