Control002

                                          

LED or Lamp Flasher
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Schematic design of LED or Lamp Flasher
Part List :
Capacitors	Resistors
C1          =    10 μF / 25V Electrolytic Transistors Q1       = BC560 Q2       = BC337	R1         =   33 KΩ ¼W R2,R3    =     47 Ω ¼W Diodes D1,(D2) = LED(s) any type and color
Notes
Designed for 3V battery operation with minimum parts counting. 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 2.2μF to 100μF 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.

Source : Electronics Lab