ES-42    RED / BLUE LED Warning Strobe Lights 
(DC 9/12V)  Works best at 12V

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OPERATION :   This circuit flashes 2 groups of super bright LEDs (red & blue) continuously  at an adjustable rate  

 The timer IC (IC1:NE555) is configured as an astable multivibrator which generate a continues square wave (frequency adjustable via PR1). This square wave is used to clock the decade counter IC2 (CD4017) with outputs (Q0,Q1,..,Q9). The outputs goes high sequentially from Q0 -> Q9 ( continuously).

The outputs are divided into 2 groups ; one group driving the RED LEDs while the other the BLUE LEDs. The forward voltage of Red LEDs is around 1.5~1.8V each whereas blue one is around 3V. For this reason,  the red LEDs are connected 4 pcs in series (total 7.2V) and the blue LEDs 3 pcs in series (total 9V).    R3 & R2 are current limiting resistors for red LEDs and blue LEDs respectively.