Simple 3-6V LED Flasher

Posted on Dec 13, 2012

If you are familiar with LED flashers using transistor, you may know the basic one uses two transistor, one capacitor and three resistors. There is other kind of oscillator called `flip-flop`. As I'm starting to develop some basic circuits, I need a simple LED flasher that can be used in many other applications. The RC circuit is connected to the base of the NPN transistor (3904) and it gives the signal to the PNP transistor (3906) to turn on the LED. When the PNP transistor is ON, it discharges the capacitor and it turn off itself, so the cycle repeats again.

Simple 3-6V LED Flasher
Click here to download the full size of the above Circuit.
Simple 3-6V LED Flasher - image 1
Click here to download the full size of the above Image.

While cleaning "the attic" a few weeks ago, I found this old project. This one uses the same circuit. It was made in 1996 or 1997. A 3 Volts lithium "coin" battery provides power up to 4 hours. The idea of this one was to get a flashing light without bulky or heavy parts. Regardless there are some LED flashers on the market, A LED with integrated circuit inside the acrylic, the cost is higher than this circuit in some cases.

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