Tuesday, December 21, 2010

Power LED Flasher

The low cost and extremely compact circuit given here is that of a highly power saving flashing LED indicator.Whereas most LEDs fail to work below 2 volt, their forward voltage alone being 1,6 volts minimum, this flasher can work off one single cell.

The LM3909 contains virtually all the essential trigger and pulsing circuitry which controls the flashing rate. The only other component used is the capacitor C1 which decides the final flashing rate, which in this case is set to about 1Hz.

The circuit has very low current has a very low current consumption, in the order of about 0.3mA, which is made possible due to intermittent current flow in the form of very short pulse through the LED. The capacitor connected across the cell ensures that the circuit continues to operate even when voltage falls below 1.2 volt (minimum limit).

The  circuit, if assembled closely on a veroboard, would occupy little extra space as compared to a conventional neon or LED indicator.

  The Schematic Power LED Flasher

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