Home Projects Motor, light and power control LED or Lamp Flasher



LED or Lamp Flasher

source: RED Free Circuit Designs


Minimum parts counting

Designed for 3V battery operation

Led Flasher


R1_______33K  1/4W Resistor
R2,R3____47R  1/4W Resistors

C1_______10F  25V Electrolytic Capacitor

D1,(D2)__LED(s) (Any type and color)

Q1_____BC560   45V 100mA PNP Transistor
Q2_____BC337   45V 800mA NPN Transistor


  • Power supply can vary from 2 to 4.5V.

  • Add D2 to obtain two LED alternate blinking.

  • D1's on-time is shorter than off-time. The opposite regarding D2.

  • You can also use D2 only, shorting D1.

  • Don't change resistors' values.

  • Flashing frequency can be varied changing C1 value from 2.2F to 100F and higher.

  • This circuit is very efficient when driving a 3.2V lamp. In this case omit the LEDs and R3, connecting the lamp at Q2's collector and to positive supply, further reducing parts counting.




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