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LED或闪光灯电路--LED or Lamp Flasher

Minimum parts counting

Designed for 3V battery operation

Parts:

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

Notes:

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.