LED Flasher Using Transistor
This simple LED flasher circuit will turn ON and OFF two LED alternatively. The first LED will turn ON when the second LED is OFF for some period, then the first led will turn OFF and the second LED will turn OFF. This cycle will be repeated as long as the battery is connected to the circuit. This LED flasher circuit can be used for your safety blinker of your bicycles or as a crossing signal for model railroads. This LED flasher circuit can be a fun stuff for your Christmas decoration or to make your Halloween’s Jack-O-lanterns blinking eyes. Here is the schematic diagram of the circuit:
This circuit is very simple, it consist only of two transistors, four resistors, two caps, and two LEDs. You can change the blinking rate of this LED flasher by changing the capacitor values, higher capacitance value for lower blinking frequency. The 470 ohm resistor limit the current through the LED. The current for LEDs is normally limited to maximum of 20mA, but you can increase the resistor values to preserve the battery life by decreasing the current. Lower brightness but longer battery life, using the components values shown in the schematic diagram, this LED flasher circuits will draw about 14 mA current (using red LEDs). This circuit can work at 3 volts, but you should change the 470 ohm resistor to 100 ohm to get brighter flashing LEDs.