Led or Lamp Flasher Circuit


This circuit was designed to provide that continuous light lamps already wired into a circuit, become flashing. Simply insert the circuit between existing lamp and negative supply. Especially suited for car or panel pilot lights, this device can drive lamps up to 10W.

Circuit diagram:

Led or Lamp Flasher Circuit-Circuit diagram


  • R1 = 6.8K
  • R2 = 270K
  • R3 = 220K
  • D1 = 1N4002
  • C1 = 220uF-25V
  • C2 = 10uF-25V
  • Q1 = BC557
  • Q2 = BD139
  • B1 = Any type in the range 3-24V
  • B1 = Suited to the lamp adopted
  • LP1 = Filament Lamp 10W-3V to 24V
  • SW1 = On-Off Switch


  • Break lamp to negative supply connection, and then insert the circuit between existing lamp connection and negative supply (respecting polarities!).
  • C1 value can be varied from 100 to 1000µF or higher, in order to change flashing frequency.
  • Although rather oversized, this circuit can also drive any LED, providing a suitable resistor is fitted in series with the light emitting device.
  • The resistor should lie in the 47R to 2K2 range, depending on supply voltage.